Review of the Standard Waste Transport Container Size and ...

TD/ETS/R/10/206 Rev 0

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I.A.Grainey. Engineering & Package Approvals. 31st March 2010

Description:

This report captures the development of Reusable Transport Container (RTC) proposals that could be used to either replace or as alternative transport packages to the current SWTC (Standard Waste Transport Container) package designs.

It encompasses all stages of the development process; from idea generation, initial development of viable options and further work on the two RTC options which most successfully met the specification criteria.

Revision and Status Prepared Checked Approved

Revision 0 Signature: Print Name: I. A. Grainey M.Ridley P.Purcell Date: Revision 1 Signature: Print Name: Date: Revision 2 Signature: Print Name: Date: Revision 3 Signature: Print Name: Date:

TD/ETS/R/10/206

Review of the Standard Waste Transport ContainerSize and Alternative Options


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Revision Record

Revision Section Description 0 - First Issue


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Contents

1 Executive Summary ........................................................................................................... 6 2 Introduction......................................................................................................................... 7 3 Approach to Work............................................................................................................... 8 4 RTC Design Selection ...................................................................................................... 10

4.1 Brainstorming of RTC Options ................................................................................. 10

4.2 Development of the 6 Identified Options.................................................................. 16

5 RTC Design Development................................................................................................ 21

5.1 Further Development of Option #1........................................................................... 21

5.2 Further Development of Option #4A ........................................................................ 34

6 Conclusions...................................................................................................................... 45 7 References ....................................................................................................................... 49 8 Appendix A – Drawings of the Options and ‘new’ Waste Packages ................................ 50 9 Appendix B – INS Report TD/ETS/R/09/202 Rev 0 ........................................................ 56 10 Appendix C – Note of RWMD Workshop................................................................... 109


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Figures

Fig. 1: RTC Development Process

Fig. 2: Comparison of Standard W6a Rail Gauge and Reduced Gauge

Fig. 3: General Views of Option#1

Fig. 4: Option#1 – Existing 4x500 litre Drums in Stillage

Fig. 5: Option#1 – Existing 3m3 Drum

Fig. 6: Option#1 – Existing 3m3 Box

Fig. 7: Option#1 – 5x500 litre Drums in new Stillage

Fig. 8: Option#1 – 4x750 litre Drums in new Stillage

Fig. 9: Option#1 – with Maximised Square Box

Fig. 10: Option#1 – with Maximised Drum

Fig. 11: Option#1 x 2 on KXA-C Wagon

Fig. 12: Option#1 x 1 on ‘Shortened’ KXA-C Wagon

Fig. 13: General Views of Option#4A

Fig. 14: Option#4A – Existing 4x500 litre Drums in Stillage

Fig. 15: Option#4A – Existing 3m3 Box

Fig. 16: Option#4A – Existing 3m3 Drum

Fig. 17: Option#4A – 4x500 litre Drums in new Stillage

Fig. 18: Option#4A – Maximised ‘Solids’ Drum

Fig. 19: Option#4A – Maximised ‘Slurry’ Drum

Fig. 20: Option#4A x 2 on KXA-C Wagon

Fig. 21: Option#4A x 1 on ‘Shortened’ KXA-C Wagon


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Tables

Table 1: Summary of the 6 RTC Options

Table 2: RTC Option#1 Comparison with SWTC-285

Table 3: RTC Option#4A Comparison with SWTC-285

Table 4: Summary of the RTC Performance Criteria compared to SWTC-285


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1 Executive Summary

NDA Radioactive Waste Management Directorate (NDA RWMD) contracted International Nuclear Services (INS) to complete a technical review of possible alternatives to the SWTC (Standard Waste Transport Container) design.

The prerequisite parameters for design options were identified as;

(a) Designs should meet the regulatory performance requirements of an IAEA Type B(M) package.

(b) The designs should be able to be transported on the UK rail network and be compliant with the rail gauge specified by RWMD.

In compliance with these requirements, INS (with RWMD input) passed through a number of development stages to identify two options which best satisfied the design intent.

The stages of the design review were;

• 1 - An internal (INS) brain-storming meeting attended by INS Engineering, Package Approvals and Flask Operations personnel which generated a number of potential ideas. From these initial concepts, the six which the attendees agreed on as being technically most viable were selected for further review.

• 2 - A more in-depth study of these six options, encompassing INS judgements on regulatory performance and rail transport reviews. These six options were presented to a joint RWMD / INS workshop and following an agreed scoring process, the two options which the meeting agreed best met the stated requirements were identified.

• 3 – Further development of the two options. Following the workshop, the selected options were reviewed in greater detail to further investigate regulatory performance and the rail transport issues / options. Further work also investigated the capability of these options to carry both the existing waste packages (i.e. SWTC compliant) and new waste packages designs which optimised use of the increased working capacity the options provided.

This report constitutes a comprehensive review of the stages identified above. Section 4 summarises the findings of the brain-storming meeting and the studies subsequently completed on the six options with all relevant data provided in the identified references / appendices. Section 5 captures the further work completed on the two options and their waste packages. Section 6 provides conclusions on further opportunities for development of this work stream. This report should be read in conjunction with drawings INS 000012, 13, 14, 16, 17 & 18.

This report outlines two viable options to the current SWTC designs.

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2 Introduction

This report constitutes the final stage of a programme of work delivered under contract to NDA Radioactive Materials Waste Management Directorate (NDA RWMD). It captures the stages of work INS has completed to arrive at two alternative design options to the SWTC (Standard Waste Transport Container) package.

INS was contracted by RWMD to identify possible alternatives to the ‘SWTC’ transport packages, the central objective being to increase waste carrying capacity as far as was practical. RWMD are seeking to examine whether the current specifications provided to waste packagers regarding size of packages could be changed to enable larger packages that approach the limits of regulatory constraint and the restrictions identified for rail transport.

Following an INS brainstorming meeting, which captured a variety of ideas, six options where taken forward and developed to a stage where they could be presented to RWMD. A meeting was then held on the 16th February 2010 with the client team to review relative option merits and provide bench-marking against the SWTC-285 design.

Using a weighted scoring process, two of the six options reviewed were identified for further development and this additional work is captured in Section 5 of this report.

This report captures the process steps completed to identify, select, and then further develop the two selected options in greater detail. During this review, areas such as regulatory performance, transport options, waste carrying capacities and manufacturability would be used to measure / gauge each option.

The report also includes reviews on the ‘new’ transport waste packages which could be transported using the transport container options identified.

It should be noted that the geometry, mass and volume of the options and waste packages indicated in Section 5 are currently based upon the INS teams engineering judgement and a limited amount of scoping level calculations.

Subsequent detailed studies (e.g. shielding analysis, impact analysis) will possibly have some marginal effects on the currently identified geometries and dimensions of these Reusable Transport Container (RTC) options.

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3 Approach to Work

The methodology used by INS to generate, (and with RWMD input) select options for further consideration in this study and develop the options for the RTC was via a stage gate process. An overview of the approach taken is captured in the diagram below.

Fig. 1 – RTC Development Process

The individual stages can be described as follows;

(1) Brainstorming – After presentation of the generic terms of reference to the attendees of the meeting i.e. a Type B(M) package is required to suit rail transport on a specific rail gauge, the INS attendees generated a number of potential ideas for the RTC. The findings of this meeting were captured in Ref 1. This report is summarised in Section 4.1 and describes how the ideas presented at the meeting were filtered to identify the 6 potentially most viable alternatives.

(2) Development of the 6 options – INS then completed scoping design studies on the 6 options, including engineering judgement reviews on each options regulatory performance, RTC

OUTPUT

INPUT

OUTPUT

INPUT

INPUT

OUTPUT

INS Brainstorming Meeting

Development of 6 Identified Options

Further development of 2 selected Options

INS Engineering, Package Approvals

and Flask Ops personnel

INS Report TD/ETS/R/09/201 Rev 0

Specification TD/ETS/S/09/307 Rev 1

and TD/ETS/R/09/201 Rev 0


plus drawings INS 000003 to 000011

inclusive

INS Engineering, Package Approval

and RWMD Attendees of review

meeting, 16th Feb 2010


(this report), plus drawings INS

000012, 13, 14, 16, 17 and 18

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mass/capacity studies, rail transport assessments and a basic review of manufacturability. This stage also included a review of the waste packages these options could transport. This stage of the project is captured in INS Report TD/ETS/R/09/202 Rev 0 (see Appendix B) and a number of drawings, which were used as the base information pack for the RWMD workshop on the 16th February 2010.

(3) The RWMD workshop compared the six RTC options using an agreed scoring / weighting process. Subsequently, the two which scored highest against the identified parameters were taken forward for further development. This additional work, captured in Section 5 of this document, reviews these options in greater detail and assesses their compliance with the identified design parameters. The section also reviews the ability of these options to transport both the existing waste packages and indicates new, larger waste package designs that could be utilised.

Section 4 reviews the first two stages in more detail, drawing on the information provided in INS Reports TD/ETS/R/09/201 and 202. The final stage i.e. the development of the two selected options, is captured in Section 5.

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4 RTC Design Selection

The content of Section 4.1 is a summarised version of the findings of INS Report TD/ETS/R/09/201 Rev 0.

4.1 Brainstorming of RTC Options

4.1.1 Summary

INS completed a brain-storming session with the objective of producing options for transport containers to carry wastes to a Geological Disposal Facility (GDF). The session attendees were supplied with the design parameters and some basic information needed to be able to generate suitable ideas, these being;

1. The container shall meet IAEA TS-R-1 requirements for a Type B(M) container.

2. The container shall be able to be transported on a W6a rail gauge.

3. The container should not be restricted to moving the existing waste package types e.g. 3m3 boxes, 3m3 drums and 500l drums.

4. An overview of the existing SWTC design was also provided – i.e. its mass, size, shielding, internal volume, etc.

Based upon this general information, eleven (11) options were generated by the team in the meeting, along with a number of design considerations that could be applied to these options in further studies. The next stage of the process involved the reduction of these options to the six which appeared to be the most viable in respect of the ability to design, manufacture and license them successfully.

Using their engineering judgement and previous experience of flask design, manufacture, operation, regulatory performance and licensing, the options were reduced to the following six;

• Option #1 – Increase ‘SWTC’ as far as possible in X-Y-Z planes.

• Option #3 – Cylindrical Container ‘Irradiated fuel type’.

• Option #4 – Short Cylinder (or polygon), vertically loaded.

• Option #5 – ‘Stretched’ SWTC.

• Option#9 – Reconfigure SWTC internals and lid retention.

• Option #10 – Design a Container with removable inserts for shielding.

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4.1.2 Introduction

An internal (INS) ‘brain-storming’ meeting was held, where a number of INS technical staff identified as many ideas as possible, having been initially provided with some basic guidance on the design requirements.

The meeting was held in Hinton House on the 26th November 2009 and was attended by INS staff from the Engineering and Package Approvals and Flask Operations sections.

A presentation was produced and delivered at the start of the meeting to ensure the audience knew the required objectives. Following this and a subsequent question / answer session, a number of possible options were suggested by the attendees. These suggestions are described in the following sections, supported by explanatory notes as required.

4.1.3 Options Generated In Brainstorming Meeting

The following options where recorded on a flip chart with suitable sketches, with all meeting attendees providing at least one idea.

Option#1 – Increase ‘SWTC’ as far as possible in X-Y-Z planes.

Description – Using W6a rail gauge dimensions and latest information on rail-wagon technology, assess how far the current SWTC can be expanded and assess how this effects both self weight of the SWTC and the internal waste package.

Option#2 – Base Container design on 20ft ISO Container sizing.

Description – Base the design of the transport container on the overall dimensions of a standard 20ft ISO container, which is known to be transportable on rail, road, sea transports, etc. This method could provide standard method of tie-downs and handling.

Option#3 – Cylindrical Container ‘Irridiated fuel type’.

Description – Use existing knowledge of cylindrical flask designs and use for this waste transport requirement. The option had horizontal loading, with possibly an integrated ‘skate’ with an attached lid to simplify loading and closure (Option was described as ‘like a cabinet drawer’).

Option#4 – Short Cylinder (or polygon), vertically loaded.

Description - An off-shoot of Option#3, but a simpler design which utilises the benefits (manufacturability, impact resistance) of a cylinder, whilst simplifying handling to vertical loading with a separate lid. A polygon (hexagonal) section may improve storage of hexagonal waste packages. Cylindrical concept could also incorporate a bayonet lid to improve lid retention in impacts.

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Option#5 – ‘Stretched’ SWTC.

Description – This option could potentially double the capacity of the existing SWTC, by stretching the design along the length of the rail-wagon, being limited only by the length / maximum load capacity of the wagon bed. The proposer stated that this could be achieved without doubling the SWTC mass, as only the sides, base and lid are extended. (i.e. no additional internal walls)

Option#6 – Smaller Containers, more often.

Description – Reduce all waste packages to size of 500l drum (for instance) and provide a large number of ‘small’ SWTC’s for transport, possibly in stillages. Advantage would be more flexible use of transport options. Could possible be integrated with an ISO frame for standard geometry and tie-down – see Option #2.

Option#7 – Spherical Flask.

Description – A spherical container could potentially provide optimised impact resistance and provided minimum surface area for a given volume, but proposer admitted there would obviously be manufacturing and handling challenges. The internal waste packages would also need to be spherical, to maximise usable volume whilst keeping the gross mass to a minimum.

Option#8 – ‘Sacrificial’ Flask.

Description – Meeting discussed the possibility of a ‘WAGR’ type disposal waste container, comprising a thin walled stainless steel construction with concrete in between to provide the required shielding. This would negate the need for internal waste packages and remove the need for flask maintenance and storage.

Option#9 – Reconfigure SWTC internals and lid retention.

Description – Idea is to leave container externals as current SWTC dimensions and concentrate effort on maximising the use of the containers internal volume. This could be achieved by removing / reducing the size of internal guides and would require the removal of the shock absorber under the lid, which would suggest the method of lid retention would need reviewing to withstand regulatory impacts. Some team members were aware of research in this area which was completed to see whether the SWTC-150 could transport damaged 3m3 boxes in an ‘over-pack’.

Option#10 – Design a Container with removable inserts for shielding.

Description – Design a container which has minimum shielding (nominally 70mm) and provide an insert(s) to increase shielding to the nominal 285mm. This would enable provision of 2 sizes of waste package, dependent upon shielding requirements and may be particularly attractive, dependent upon proportions of the waste streams. It was suggested that this idea could be made applicable to a number of the options, with the central issue being identification of how to secure the insert adequately to withstand the regulatory impacts.

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Option#11 – Integrate Container into the rail wagon.

Description – This option would integrate the container / transport mode and in so doing, would minimise the structural design and incorporate the wagon structure as part of the shielding capability. However, many issues where immediately identified against this options further progression e.g. rail access to all waste producer sites required (and into plant / cell potentially), regulatory drop testing issues, manufacturing issues, Department for Transport (DfT) unfamiliarity with concept.

4.1.4 Design Considerations Generated

Along with the identified options, a number of other points were raised which on review, were seen to be equally applicable to all and would be reviewed for the options taken forward. The identified issues are captured below;

• Using the W6a rail gauge profile as a guide, maximise cross-sectional profile of flask as far as is practical (already part of some options).

• Remove internal waste packages completely and tip waste directly from flask. Obvious issues with some (i.e. the liquid and/or grouted) wastes, but will be reviewed.

• Shielding thicknesses is based on steel. Possible use of denser materials, such as tungsten, depleted uranium, lead, assess volumetric effects, material costs, manufacturability, issues with toxicity, etc.

4.1.5 Selected options to progress

Following the initial brain-storming of ideas, the INS team was asked to consider the pro’s / con’s of each idea and decide individually upon the six* which should be taken forward for further review.

*Six options were identified for progression as this number provided the best fit with the delivery programme, whilst ensuring a suitable range of options had been reviewed in greater detail.

The following summarises which options have been selected for the next stage and why.

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Option #1 – Increase ‘SWTC’ as far as possible in X-Y-Z planes.

SELECTED – the team thought it would be sensible to review the current SWTC design and review how its volume could be maximised when all current legislation and regulations are taken into consideration.

Option#2 – Base Container design on 20ft ISO Container sizing.

NOT SELECTED – This option uses the dimensions / volumes of a standard transport method and suggested a possible standardisation of tie-downs / handling. However, given the shielding requirements, it quickly became evident to the team that the total mass would be restrictive and would negate lifting / tie-down by standard ISO means.

Option#3 – Cylindrical Container ‘Irradiated fuel type’.

SELECTED – Idea is to use thick-walled irradiated fuel flasks as a basis of the design, thus making use of proven methods of design / construction. As presented, the option also suggested some novel concepts (e.g. horizontal loading, integral ‘bayonet’ lid) which would need to be investigated in more detail. Waste packages would also be cylindrical to minimise ullage. This would reduce waste storage efficiency in the repository.

Option#4 – Short Cylinder (or polygon), vertically loaded.

SELECTED – Similar to Option #3 if flask is cylindrical, but utilising vertical loading with separate lid and therefore generally simpler. Advantage over SWTC in principle would be improved impact performance and possibly easier manufacturing process. Cylindrical variant could also incorporate a bayonet lid to strengthen body lid connection and simplify closure process. The hexagonal flask variant could carry hexagonal waste packages (improved storage in repository) and reduce the ullage space for any cylindrical waste packages transported.

Option#5 – ‘Stretched’ SWTC.

SELECTED – Idea is to stretch SWTC along the length of the rail-wagon, using total mass as guide to the allowable volumetric increase.

Option#6 – Smaller Containers, more often.

NOT SELECTED – Idea of more, smaller transport containers means increase in handling, manufacture, inspection, maintenance, increase in waste size reduction requirements and ultimately increase of waste when flasks are decommissioned. Option was not taken forward on this basis.

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Option#7 – Spherical Flask.

NOT SELECTED – Optimised impact performance, but would require waste packages to also be spherical to avoid excess shielding. Major manufacturing issues meant idea was not taken forward.

Option#8 – ‘Sacrificial’ Flask.

NOT SELECTED – Although disposal of the flask would present a significant reduction in handling, materials of construction (reinforced concrete) would present impact capability issues and a lot of material would be being disposed of which was not actual waste i.e. reduced storage efficiency. Concrete shielding also implies an increase in shielding thickness, which would further effect storage efficiencies.

Option#9 – Reconfigure SWTC internals and lid retention.

SELECTED – idea is to reconfigure lid design, thus increasing the useable volume. Option would also review the size of the guides within the SWTC. This was seen as a simple way in which to evaluate how the existing design could be improved regards useable volume.

Option#10 – Design a Container with removable inserts for shielding.

SELECTED – Idea is to provide a container design which utilises the minimum required shielding (i.e. 70mm steel) and then use liner(s) as required to bring shielding up to equivalent of 285mm steel. Validity of option depends upon identifying a suitable method of locking in liners and the proportions of waste streams requiring 70mm v 285 mm of steel shielding i.e. if total numbers of 285mm shielding variants is proportionally low based upon the total number of transports, then this option has increased attraction.

Option#11 – Integrate Container into the rail wagon.

NOT SELECTED – Integrate the container and the transport mode. Major obstacles to this option, which would require major strategic re-thinking at waste arising and disposal sites and a completely novel flask / transport interface. Not taken forward as viewed as technically unfeasible.

The six ideas captured in Section 4.1.1. were taken to the next stage of the process, were further work was undertaken to better understand their individual performance against the functional specification requirements.

The findings of this stage of the work are summarised below in Section 4.2. A complete unedited copy of INS Report TD/ETS/R/09/202 Rev 0 can be found in Appendix B of this document.

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4.2 Development of the 6 Identified Options

The following is a summarised version of the findings of INS Report TD/ETS/R/09/202 Rev 0. (See Appendix B) This report was used at the RWMD workshop to review the options and enable the scoring to be completed.

4.2.1 Packaging Requirements

Each of the RTC options was assessed against the requirements of a B(M) package, as is described in the Regulations for the Safe Transport of Radioactive Material, TS-R-1 (Ref. 2). Engineering judgement and previous knowledge of transport package design was employed by the INS project team to review each option against regulatory accident requirements, e.g. impact, fire, etc and good engineering design principles.

4.2.2 Transport Requirements

The development of the six RTC options was progressed on the premise that transport will be primarily by rail, with each option being required to satisfy the rail gauge and Route Availability (RA) requirements stipulated in the Functional Specification.

As Section 2.3 of INS Report TD/ETS/R/09/202 Rev 0 explains, it quickly became apparent to the INS team that a 4-axle bogie would not be able to meet the axle limit requirements, due to the increased masses of the RTC options. Following discussions with Rail Engineers from Network Rail, a 6-axle wagon option was quickly discounted as having serious technical challenges and therefore an 8-axle wagon was identified as being needed to transport the RTC options.

As INS had recently received a number of 8-axle wagons and the design data for these was available to the INS team, this wagon design (the KXA-C) was used to provide further technical underpinning to options viability regards axle limits and compliance with the identified rail gauge. NB – The KXA-C is currently the largest capacity wagon on the UK rail net-work.

The six options (as far as was practical) used the tie-down methodology suggested for the SWTC and therefore any 8-axle rail wagon would need to incorporate a suitable interfacing tie-down mechanism.

RWMD will need to consider whether development of a container which requires an 8 axle rail wagon is feasible at this stage when no site for a GDF has been identified. The use of 8 axle rail wagons may limit transport to certain parts of the national rail network and possibly waste producer sites.

4.2.3 Materials of Construction

For each option, a material review concentrated on the RTC body, as this is the component of highest cost, longest lead-time and is obviously critical to the RTC performance in both normal and accident regulatory conditions. The material specified for the SWTC body is CA6NM and this was used as the baseline body material for the options.

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A limited number of alternative materials which would provide the necessary mechanical properties were also considered and these were captured in the individual assessments.

4.2.4 Manufacturability

The report concentrated on the ‘theoretical’ ability to manufacture the RTC body, using proven methods, within the UK or overseas. As Option#5 presented the biggest challenge regards the amount of material required, its geometry was provided to suppliers to ensure it could be manufactured. As the suppliers stated that this bounding case option could be made, it implied that the other options, being smaller and of less mass, could also be produced successfully.

4.2.5 Weather Protection and Available Rail Gauge

The INS team realised that the weather protection provided during rail transport for the SWTC was effectively limiting the overall size (width) of the container. It has been assumed, for the purpose of this study, that weather protection, if offered, would not limit the width of the RTC.

Section 2.8 of INS Report TD/ETS/R/09/202 Rev 0 provides an alternative method of protecting the RTC lid from water ingress. Although this appears to be technically viable, discussions at the RWMD workshop suggested that the issue of whether the existing SWTC covers were solely providing weather protection, or had a greater ‘stakeholder engagement’ purpose was discussed. RWMD took this issue away to review, as the need for such ‘protection’ will undoubtedly affect the final design of the RTC.

This study requires that the RTC be transported by rail, using the W6a Rail Gauge. This gauge is one of the most restrictive on the UK rail network, but, designs which comply with this gauge can be used across a larger proportion of the network. This therefore provides greater flexibility for the location of a GDF.

The existing SWTC designs use a proportion of the W6a gauge envelope for retractable covers. To enable any appreciable increase in width over the existing SWTC, the RTC is required to make use of this space and in doing so, would interfere and prevent the operation of this type of cover. For the purpose of this study and to enable the maximum RTC width to be calculated these retractable covers were ignored, noting that many RAM (Radioactive Material) shipments are currently made without such covers being used.

Based on the RTC transports requiring a suitable 8 axle rail wagon, the width of the W6a gauge needed to be reduced. Short wagons can use the maximum width of the gauge, but beyond a certain overall length, wagons with long beds and larger bogie/wheel centres have a reduced gauge width to limit over-throw when the wagon is cornering. Based on the transportation of the RTC using this type of wagon, the useable width of the W6a gauge was calculated to be 2690mm (see Fig 2 overleaf).

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Fig 2: Comparison of Standard W6A Rail Gauge and Reduced W6a

Standard calculations that show how this width reduction is derived can be found in Ref 3. This value of 2690mm provides the bounding parameter for the width of the RTC designs that have been progressed.

The table overleaf summarises the general information provided for each of the 6 options in the report tabled at the RWMD Workshop, 16.02.2010.

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Option No: #1 #3 #4A/B #5 #9A/B/C #10

Brief Description SWTC geometry

expanded in 3-planes

Cylindrical package –

‘Irridiated fuel type’

Short cylinder (or polygon)

vertical load

Option#1 stretched along

rail bed

Reconfigure Option#1 lid

attachment to extend

cavity (3 sub-options)

Reduced wall Option#1

with removable liners

No of 500l drums 5 6 4 (A and B) 8 5 5

Net mass (kg) 63850 80850 53000(A), 56100(B) 93900 64000(A), 64700(B),

58000(C)

59350

Gross mass (kg) 79300 108850 66350(A), 70950(B) 124250 80150(A), 82450(B),

75100(C)

78050

Internal volume (versus SWTC

design)

+21% +114% +8.1%(A)*, +7.7%(B)

*corrected at Workshop

+130% +19.7%(A), +31.5%(B),

+26.6%(C)

+37%

Identified Pro’s Increase in cavity volume,

Similar configuration as

SWTC, improved thermal

performance, could carry

all existing waste

packages

Very large cavity volume,

‘proven’ design type,

response to regulatory

accident conditions likely

to be improved over

‘cuboid’ designs

Simpler manufacture (A),

simpler seal (A), improved

impact (A), can carry 4 x

500l drums (A+B),

Bespoke waste package is

good for storage (B)

Very large cavity volume,

could carry 2 x 3m3 boxes

or drums

Increased capacity over

#1 (A,B,C) Lid retention

less reliant on bolts(A),

reduced bolt torques(A),

Improved impact(B),

isolation of impact / seal

system (C)

Provides a ‘multi-purpose’

design, use of 150mm

casting (or forging) will

provide some cost

savings, waste packages

requiring less shielding

can be larger

Identified Con’s Increase mass may

challenge user facilities,

impact performance

reduced versus SWTC

More complex handling,

more ancillary equipment,

high mass, cannot carry

3m3 box or drum, high

impact on user facilities

Cannot carry 3m3 box or

drum (A+B), B more

difficult to manufacture

compared to A, increased

manufacturing issues (B)

Impact performance

questionable, fire accident

performance probably

poor – thermal strains,

challenge to user sites

regards size, mass, body

>2x cost of Option#1 body

Complex, unproven lid

arrangement (A), potential

lid jamming(A), Female

threads require

maintenance (B), complex

lid fitting (C), difficult to

access test point (C)

Difficult to lock-in the liner

to resist impacts, lead liner

– toxicity issues during

manufacture, ability to

make liner strong enough

in limit space will be

challenging

Table 1: Summary of the 6 RTC Options

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The RWMD Workshop used the information summarised above in Table 1 (and fully provided in Appendix B of this report) to score each of the options against an agreed number of parameters.

The minutes of this Workshop are provided in Appendix C and these capture how the two most suitable options were selected from the six presented for review.

Section 5 below captures the additional studies completed on the two selected options, namely Option#1 and Option#4A.

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5 RTC Design Development

5.1 Further Development of Option #1

Fig. 3: General Views of Option#1

5.1.1 Brief Description

The W6a rail gauge width and height were used as the volumetric limits to ‘inflate’ the dimensions of the Option as far as possible (assuming that the RTC length remains equal to the increased width).

The general configuration of this option is identical to the SWTC and therefore the general method of operation would be the same, notwithstanding the substantial increase in mass to be handled. The container lifting methodology is of the same principle as the SWTC and this is

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reviewed in Section 5.1.10, noting that the increased lift centres may affect the design of the lifting equipment currently designed for the SWTC.

The tie-down method used for the SWTC-285 was duplicated for this option and no major problems are envisaged with ensuring this restraint system could meet the requirements of IAEA TS-R-1 transport regulations.

Views of the General Assembly drawings of Option#1 can be found in Appendix A and RWMD will be supplied with the associated AutoCAD files.

5.1.2 Volumetric Comparison with SWTC-285

Table 2: RTC Option#1 Comparison with SWTC-285

SWTC-285 Option Increase

Overall Height (mm) 2175 2261 + 86mm

Overall Width (mm) 2410 2670 + 260mm

Overall Length (mm) 2410 2670 +260 mm

Internal Volume (m3) 4.31* 5.52* + 21 %

Container Mass (kg) 52000 59800 +7800 kg

3m3 Waste Package Revised Waste Package

Approx. Total Volume (m3) 3.36 4.42 +31.5%

‘Filled’ Package Mass (kg) 12000 15783 +3783kg

Combined Mass (kg)

(i.e. Container + Package)

64000 75600 + 11600 kg

*The values provided here ignore the volume taken up by the internal shock absorber, as its thickness will change when detailed impact analysis is conducted. Internal height is therefore measured to the underside of the container lid. The maximum height of the waste packages for the new container is currently based upon a linear relation increase in the depth of the internal shock absorber, derived from the additional container mass.

5.1.3 Comments on Regulatory Performance

As the above table relates, the RTC internal volume is 21% larger by volume than the SWTC-285 and its mass has correspondingly increased by 15.0%. These increases will affect the performance of the RTC in IAEA regulatory accident conditions and these are discussed below;

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- Fire Accident

The increase in RTC mass suggests that during the transient, there would be a decrease in the temperature gradient through the walls during the fire. This is because the percentage increase in overall mass is slightly greater than the overall increase in external area, hence it would take longer to heat up and therefore the temperature at the end of the 30 minute fire would be lower than for the standard SWTC. On this basis, it is predicted that under fire accident conditions this will result in lower temperatures at the lid seal positions. Reducing temperatures in these areas reduce the risk of the lid bowing, and hence should improve containment performance.

- Impact Accident (9m drop)

Due to an increased mass compared to the standard SWTC a corresponding increase in shock absorbing performance will be required to protect the lid sealing system. Additional lid retaining bolts may be required to ensure regulatory compliance. Provided these can be achieved, there should be no other issues arising due to higher impact accelerations. This assumes such accelerations would not cause substantial damage to the internal waste packages. At this stage and in the absence of a detailed analysis it is unrealistic to be confident of the impact response of this heavier package. Detailed design and analysis may show that regulatory compliance is only achievable by reducing the mass and/or load capacity currently proposed for this option.

- Impact Accident (1m punch)

The obvious target area for the punch test is the test point cover since this was targeted during the test regime completed on the SWTC-285 model. Clearly with the increased mass of the enlarged SWTC the orifice becomes more vulnerable to punch damage and this may have to be addressed by providing additional protection to this feature, although this is not envisaged to be otherwise restrictive on overall package performance. Elsewhere on Option#1, despite the additional mass, it is not envisaged that a punch impact will present any issues.

- 200m Immersion

Although larger than the standard SWTC, Option #1 will not have any problems complying with the 200m immersion test. Previous analysis shows that there are large margins of compliance with the standard SWTC (Ref. 4) and although these may be reduced slightly for Option#1, a large margin will remain.

5.1.4 Interfacing with existing Waste Packages

This option will be capable of carrying all existing waste packages, but would require either replacement of the internal guides or more likely, an additional interface liner to ensure that the waste packages / stillages remained centrally located in the RTC cavity. The lid would also need a specific shock absorbing structure to be attached to the underside of the lid to minimise the gap to that present in the SWTC-285 / 3m3 box / drum waste package interface. Whether these operational modifications are required or not is subject to RWMD strategy i.e. whether the RTC will be used to transport both the existing and new waste packages, or focus

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solely on transport of the new waste packages. If dual use is required, one internal shock absorber may indeed be sufficient, but verification of this would be subject to detailed impact analysis.

The following images provide the reader with an indication of the existing waste packages within Option #1’s cavity. Also indicated are the approximate total masses (i.e. with the RTC lid fitted and including an estimated mass for an interface structure, if required) as well as the clearances between the waste packages (denoted w/p below) and the internal walls of the RTC.

Total Mass = 68.6te, Clearance all round w/p = 182.5mm

Fig. 4: Option #1 – Existing 4x500 litre Drums in Stillage

Estimated Total Mass (closed) = 71.8te, Clearance all round w/p =155mm

Fig. 5: Option #1 – Existing 3m3 Drum

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Estimated Total Mass (closed) = 71.8te, Clearance all round w/p =155mm

Fig. 6: Option #1 – Existing 3m3 Box

5.1.5 Interfacing with ‘new’ Waste Packages / Stillages

The increase in the useable cavity enables larger waste packages to be transported. It will also enable 5 x 500 litre or 4 x 750 litre (new) drums to be transported. New stillages would be required for both options. The overall size of these new designs (and stillages) is compliant with the existing clearances between the waste packages and the SWTC-285 i.e. 30mm per side. This has been used as a parameter in the new waste package designs to ensure that remote loading is still achievable. The following images provide an indication of what the designs would look like when used in conjunction with Option #1. Also indicated are approximate masses for the complete RTC assembly (i.e. Body, Lid, w/p and stillages)

Total Mass = 70.4te, Clearance all round w/p =30mm

Fig. 7: Option #1 – 5x500 litre Drums in new Stillage

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Fig. 8: Option #1 – 4x750litre Drums in new Stillage


Fig. 9: Option #1 – Maximised Square Box

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Total Mass= 72.7te, Clearance all round w/p =30mm

Fig. 10: Option #1 – Maximised Drum

5.1.6 Overview of the ‘new’ Waste Packages / Stillages

The larger waste packages / stillages shown in Section 5.1.5 would use the same materials of construction as the existing packages i.e. austenitic stainless steels. Although the overall sizes of the plate / sheet making up the packages will obviously increase, they remain within the standard sizes available (Ref. 5) and therefore it is considered that there will be no requirement to include any additional ‘make-up’ welds. Manufacture of these packages will require specific jigs and fixtures to be developed, but as these exist for the current waste packages, there is no technical reason to suggest that this cannot be done for these slightly larger versions.

A major consideration of the new waste packages is the positioning of the twist-lock lift points. The positions of these (i.e. the lift centres) has been increased from those on the existing designs for a number of important reasons;

(1) It enables the lid and hence the lid opening aperture in the body to be maximised, thus allowing larger (and/or longer items) to be placed into the waste package.

(2) If the existing lift centres had been maintained a more complex method of transferring the load through the structure of the package would be required (e.g. cantilevered lifting points). It is likely that modifications of this sort would reduce the useable volume within the packages.

(3) If in-situ grouting / stirring is required, internal structures need to be avoided or moved as far from the package centreline as possible.

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It is considered therefore that the appropriate approach is to provide either a second lifting assembly design to handle these new packages, or design one that can be adjusted to suit either the existing (SWTC type) or new waste package lift centres.

Clarification of whether the existing or the new lift centres are to be used would need to be stated as a functional requirement at commencement of the detail design, as this will be a fundamental constraint on these designs.

References 6 and 7 have been reviewed and it is suggested that considering the requirements of these reference documents, there are no insurmountable technical issues that would prevent successful manufacture of these waste packages.

Views of the General Assembly drawings of the new waste packages for Option#1 can be found in Appendix A and RWMD will be supplied with the associated AutoCAD files.

5.1.7 Transport on existing INS KXA-C Rail Wagon

The ability to transport 2 x Option#1 with the maximum payload (new square waste package) has been assessed regards the rail transport. The assessment is based upon the use of the KXA-C rail wagon and includes the requirement of a tie-down frame to enable securing of the RTC’s to the rail-wagon base.

Item No. off Mass (te)

RTC * 2 151.1

Tie-down Frame

1 Est. 3

KXA-C 1 53.5

Total 207.6

* max loaded condition

Fig. 11: Option#1 x 2 on KXA-C Wagon

The load per axle in this instance is therefore 207.6 / 8 = 25.95 te/axle. This required axle rating suggests the following;

• Route availability will be very limited, possibly restricting use to ‘private sites’

• Network Rail suggests that with 25te rated axles (which this currently exceeds) axle centres would need to increase from 1.8m to 2.0m. This would increase over-throw and hence further reductions to the Rail Gauge and RTC width.

• The KXA-C could not be used for this ‘double’ transport. The current axles are rated at 22.5te / axle and this is with a restriction on the mileage these wagons can complete.

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• Increasing the axles rating to +25te would greatly restrict use of this wagon. On this basis, the KXA-C could not be used for this transport

The above points clearly suggest that this RTC option could not be transported in pairs.

An alternative option would be to carry a single RTC on the KXA-C. This, in its maximum configuration, would give a gross weight of 129.1Te + suitable tie-down arrangement (3te approx). Load per axle in this instance is therefore 132.1/8 = 16.5te/axle. This required axle rating suggests the following;

• Reducing the axle load would reduce the restrictions on Route Availability (RA)

• Axle centres remain at 1800mm, therefore maintaining the rail gauge width.

• Reducing the KXA-C all-up-weight may allow the mileage restrictions to be reduced (detailed FEA analysis required).

It should be remembered that the KXA-C’s are currently the highest capacity wagons operating on the UK network.

The following section reviews the possibility of shortening the KXA-C design and reducing the bed length so that it is sized to transport a single RTC.

5.1.8 Transport on ‘Shortened KXA-C’ Rail Wagon

The KXA-C 3D model was manipulated to reduce the wagon bed to a length suitable for carrying a single Option#1 RTC. It has been assumed that the tie-down system could be integrated into the bed of this new rail wagon.


RTC * 1 75.55

‘new’ wagon

1 48.2

Total 123.8

* max loaded condition

Fig 12: Option#1 x 1 on ‘Shortened’ KXA-C wagon


• Reducing the axle load would reduce the restrictions on Route Availability (RA).

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• Specifying 18te rated axles (a standard size) would present a substantial cost saving over the 22.5te rated axles on the KXA-C’s.

• The bed of the wagon could integrate the tie-down system.

A new rail wagon would therefore present some advantages over attempting to carry 2 RTC’s on the same wagon.

It should be noted that a single RTC could still be transported on the existing KXA-C’s, but a tie-down frame would be required (i.e. a single transport version of the one briefly discussed in Section 5.1.7).

5.1.9 Interface at a Geological Disposal Facility (GDF)

During the meeting of the 16th February, discussions took place on the ability of the various options to interface with the current design specifications for a GDF. A central issue identified by the RWMD Mining Engineers was the lift capacity of equipment in the GDF shafts and drifts, which is currently understood to be limited to 80 tonnes. A further issue which needed to be considered was the limited space (i.e. vault clearance) available within a GDF for the unloading of waste packages from the RTC.

At this point of its development, the maximum mass of the Option #1 RTC with the heaviest possible waste package is 75.6 tonnes, indicating that it is currently compliant with GDF equipment specifications. The operation of the package is also the same as the SWTC-285 and only requires a nominal increase in head-room during opening of the RTC and removal of the waste packages.

5.1.10 Lifting Review – RTC Body

The following assessment is based upon the scoping calculations provided in Section 6.2 of RWE Solutions Document TR/21238/001 and assumes the RTC body material is CA6NM.

The lifting point arrangement is assumed to be the same in principle to that shown in Figure 19 of the above reference. The maximum loaded mass of Option #1 is 75.6te.

It is assumed that the load acts on only 2 of the 4 lift points and an impact factor of 1.3 is applied (BS 2573).

Load acting on each lift point is,

(75600 (9.81)) /2 x 1.3 = 482kN.

Shear stress acting upon resisting section is,

482000 / 2 x ((75+60)/2) x 34.5 = 103.5MPa.

Allowable shear stress (to BS 2573 requirements) for body material = 550 x 0.37 = 204MPa

SF = 204/103.5 = 2

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Bearing stress acting is,

482000/ 75x90 = 71.4MPa

Allowable bearing stress (to BS 2573 requirements) for body material = 550 x 0.8 = 440MPa

SF = 440/71.4 = 6.2

Therefore, the existing lifting point design for the SWTC-285 could also be integrated into the designs for Option #1.

5.1.11 Review of Leak Rates versus SWTC-285

Although Option#1 is larger than the standard SWTC, it will not be necessary to increase the size of the orifice in the lid and hence the corresponding seal lengths in the orifice will not change.

However, the lid itself and therefore the lid sealing system would be larger in Option#1. A review of the 3D SolidWorks model suggests the overall seal length has increased by about 15% over the lid seal length in the SWTC. The consequence of this increased length would be;

a. To increase potential permeation losses b. To increase inter-space test volumes c. To increase potential by-pass leakage.

All these effects would have some negative influence on the leak testing procedure, insofar that the test acceptance criteria would involve a smaller pressure drop (assuming a pressure drop test method is used).

In addition, the potentially larger volume of waste increases the activity in the cavity and perhaps the maximum cavity pressure, both these effects having consequences on the required acceptance standard for a test.

Although Option#1 will involve the resolution of the above sealing issues, it is considered that these should not prove to be a limiting factor against the viability of Option#1 and that a workable leak tightness measurement system can be developed.

However, the following points should be considered in any future development of this option. The SWTC leak tightness criteria was set at a lower standard than the generally accepted ‘leak-tight’ criteria of 10-6 bar.cm3/s and the containment argument had to be made whilst taking account of the form of the particulate in the cavity. The longer seal of this option will have an effect on the arguments made for the SWTC parameters, which is already complicated. The logic of the arguments for this option will require careful consideration, taking into account the following;

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• The higher measured leakage across the seal due to its increased length implies a reduced activity source term in the container cavity to comply with regulatory release rates from the RTC. This in turn implies less activity in the waste package, assuming the release rate is as previously used. This could potentially undermine the requirement to carry more waste (more activity) in the new packages.

It is suggested that a separate study on this issue is required, since the adhesion and agglomeration theory could result in there being minimal difference between the performance of the existing packages and those proposed for use in this RTC option.

5.1.12 Review of Shielding

This option offers a significant increase in cavity volume and therefore a corresponding increase in the amount of waste that may be carried. It is based on a previously agreed shielding thickness of 280mm which has achieved an acceptable radiation shielding performance for the standard SWTC. It is evident that an increase in the volume of waste being transported will involve a corresponding increase in the radiation source. Although detailed shielding analysis has not been conducted on Option#1, it is judged at this time that an increase in the shielding thickness will not be required.

This statement can be made as;

a. Self shielding from the larger waste volume itself will act to attenuate some of the additional radiation.

b. The increase in the body mass, including the use of 285mm thickness for this study instead of 280mm, should ensure that there are no new shielding issues with the current enlarged package.

Detail shielding analysis may show that 280mm of shielding is still adequate for this RTC. If so, further increases in the waste container size may be achievable.

5.1.13 Manufacturability and Materials of Construction

The critical component of the RTC design in respect of manufacture is the package body, as this presents the greatest technical challenges regards the need to ensure the geometry of the body is within tolerance, the materials of construction are sound and they possess mechanical properties that satisfy the requirements of a Type B(M) package. Following advice from Sellafield Limited metallurgists, INS approached an industrial body named Casting Technology International (Cti) to review the proposed geometry of the Option #1 body and provide manufacturing costs and advice on materials of construction. Cti is Europe’s leading centre of excellence on casting and is dedicated to providing independent R&D, technical support and consultancy services to the castings and metal related industry. Cti were provided with the geometry of the Option #1 body and asked (a) whether it could be manufactured, (b) to provide an estimated cost of manufacture and (c) whether they could suggest any suitable alternative materials to the CA6NM material specified for the SWTC.

http://www.castingstechnology.com/public/services/researchdev/RDMain.asp

http://www.castingstechnology.com/public/services/technicalservices/TCSTechnicalSupport.asp

http://www.castingstechnology.com/public/services/technicalservices/TCSprojectManagementandConsultancy.asp

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Following their review, Cti provided the following information;

(a) The body of Option#1 could be successfully cast (b) The cost of this casting would be approximately £300k, exclusive of NDT inspection

and machining costs. (c) CA6NM material is viable for this casting size. (d) Material 1.4317 is a possible alternative that would meet the mechanical property

requirements stipulated. Cti also added the following comments which are worth capturing here for future reference; ‘…To produce a sound part the foundry may wish to change the shape by adding ribs or pads to aid solidification. These could be removed by machining (further cost) or left in situ depending on the design criteria. Therefore the weight of the casting design could be higher than the initial concept design. As a consequence of this and the liquid metal weights involved, the foundry will need to be intimately involved at a early stage - i.e. logistics of holding, transfer, quality assurance etc will be critical in terms of what can be achieved’ The suggested cost of the body casting indicates a probable manufacturing cost in the order of £500-700k for a complete RTC of this design. Cti suggested that if this work is progressed further, Sheffield Forgemasters Ltd (or a suitable alternative) could provide more detail manufacturing costs and as stated above, should be engaged with as soon as possible to ensure all technical requirements are fully specified and met. INS has reviewed the material currently identified for the SWTC body and the external expert has verified that it is suitable for this intended use. Although one alternative material has been provided (1.4317) it is suggested that a more detailed study is undertaken on materials to identify the full range of applicable materials, taking into consideration mechanical properties requirements, density (for shielding), manufacturing issues and cost to identify the most cost effective solution. RWMD work on the SWTC designs identified that there may be a possible issue with the size of pours during the casting process and whether multiple pours would affect material properties. This needs clarifying and should be reviewed in any subsequent study. Section 5.2 now reviews Option#4A.

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5.2 Further Development of Option #4A

Fig. 13: General Views of Option#4A

5.2.1 Brief Description

Option #4A is a circular, top loading RTC with its diameter maximised in relation to the W6a rail gauge.

This option offers a marginal volume improvement over the standard SWTC. It has a uniform shape and would therefore be expected to perform better in impact and fire accident conditions in comparison to Option#1. Manufacturing cost would also be slightly reduced (See Section 5.2.13). However, the option obviously does not lend itself to the transport of the existing square waste packages / stillages and these could not be transported in this RTC.

The container lifting methodology is the same principle as for the SWTC and this is reviewed in Section 5.2.10, noting that the re-orientation of the lift centres may challenge the design of the lifting equipment currently designed for the SWTC.

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Views of the General Assembly drawings of Option#4A can be found in Appendix A and RWMD will be supplied with the associated AutoCAD files.

5.2.2 Volumetric Comparison with SWTC-285

Table 3: RTC Option 4A Comparison with SWTC-285


Overall Height (mm) 2175 2360 + 185 mm

Overall Width 2410 2670 Diameter + 260 mm

Internal Volume (m3) 4.31* 4.66* + 8.1 %

Container Mass (kg) 52000 50300 - 1700 kg


Approx. Total Volume (m3) 3.36 3.73 +11.1 %

‘Filled’ Package Mass (kg) 12000 13325 + 1325 kg

Combined Mass (kg)


64000 63625 - 375 kg

*The values provided here ignore the volume taken up by the internal shock absorber, as its thickness will change when detailed impact analysis is conducted. Internal height is therefore measured to the underside of the container lid. The maximum height of the waste packages for the new container is currently based upon a linear relation increase in the depth of the internal shock absorber, derived from the container mass.

5.2.3 Comments on Regulatory Performance

As shown in the above Table, Option#4A is slightly lighter than the standard SWTC and it is judged that due to this and its inherent geometry, under most accident conditions Option#4A will perform as well or better than the current design.

- Fire Accident

The slightly reduced mass of Option#4A, compared to the standard SWTC, will serve to decrease its thermal inertia and thereby slightly increase overall temperatures at the end of the fire. However, the reduction in external area, compared to its mass, will serve to reduce temperature build up in a fire. Being circular in design, potential distortion during a fire accident will also be minimised compared to the standard SWTC.

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- Impact Accident (9m drop)

Due to its reduced mass when compared to the SWTC, it is safe to assume Option#4A will have better performance during a 9m impact. This is because the regular geometry of the cylindrical design will ensure consistent responses over a wide range of lateral and end impacts. Being circular, there is also a much better prospect of avoiding stress concentrations at the corners which can be a negative feature of ‘square’ package designs under 9m impacts. The continuous shock absorbers of this option on both the lid and body also increase the level of protection provided during an impact scenario.

- Punch Impact (1m drop)

Again, Option#4A should perform at least as well as the standard SWTC when the punch is aimed at the orifice in the lid. The geometry of this option means all other punch impacts would be less severe than on the SWTC designs.

- 200m Immersion

The standard SWTC meets this test requirement with a large margin of compliance; therefore due to its circular geometry, Option#4A is expected to perform better under the 200m immersion test.

5.2.4 Interfacing with existing Waste Packages

This option cannot carry any of the existing cuboid waste packages or the 500 litre drum stillage. The existing 3m3 drum can be carried, but would require either replacement of the internal guides or more likely, an additional interface liner to ensure that the waste package remained centrally located in the RTC cavity. As with Option#1, the lid would also need a specific shock absorbing structure to be attached to the underside of the lid to minimise the gap to that present in the SWTC-285 / 3m3 drum waste package interface (noting the comments on this point already made for Option#1).

The images overleaf provide the reader with an indication of the existing waste packages within Option #4A’s cavity and indicate when clashes occur. Also indicated are the approximate total masses (i.e. with the RTC lid fitted and including an estimated mass for an interface structure, if required) as well as the clearances between the waste packages (denoted w/p below) and the internal walls of the RTC.

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Total Mass = 59.0te, Interference = 182.5mm

Fig. 14: Option #4A – Existing 4x500 litre Drums in Stillage

Total Mass = 62.5te, Interference = 25.6mm

Fig. 15: Option #4A – Existing 3m3 Box

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Fig. 16: Option #4A – Existing 3m3 Drum

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5.2.5 Interfacing with ‘new’ Waste Packages / Stillages

The smaller increase in the useable cavity leads to a more restricted variety of new waste packages to be transported in comparison to Option #1. It will enable 4 x 500 litre drums to be transported if a new stillage is provided. The overall size of these new designs (and stillages) is compliant with the existing clearances between the waste packages and the SWTC-285 i.e. 30mm per side. This has been used as a parameter in the new waste package designs to ensure that remote loading is still achievable. The following images provide an indication of what the ‘new’ designs look like when used in conjunction with Option #4A’s. Also indicated are approximate masses for the complete RTC assembly (i.e. Body, Lid, w/p and stillages).

Total Mass = 58.9te, Clearance all round w/p = 30mm

Fig. 17: Option #4A – 4x500 litre Drums in new Stillage

Total Mass = 63.6te, Clearance all round w/p = 30mm

Fig. 18: Option #4A – Maximised ‘Solids’ Drum

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Total Mass = 62.8.0te , Clearance all round w/p = 30mm

Fig. 19: Option #4A – Maximised ‘Slurry’ Drum

5.2.6 Overview of the ‘new’ Waste Packages / Stillages

The larger waste packages / stillages shown in Section 5.2.5 would use the same materials of construction as the existing packages i.e. austenitic stainless steels. Although the overall sizes of the plate / sheet making up the packages will obviously increase, they remain within the standard sizes available and therefore it is considered that there will be no requirement to include any additional ‘make-up’ welds. Manufacture of these packages will require specific jigs and fixtures to be developed, but as these exist for the current waste packages, there is no technical reason to suggest that this cannot be done for these slightly larger versions.

A major consideration of the new waste packages is the positioning of the twist-lock lift points. The positions of these (i.e. the lift centres) has been increased from those on the existing designs for three important reasons;

(1) It enables the lid and hence the lid opening aperture in the body to be maximised, thus allowing larger (and/or longer items) to be placed into the waste package.

(2) If the existing lift centres had been maintained, a more complex method of transferring the load through the structure of the package would be required (e.g. cantilevered lifting points). It is likely that modifications of this sort would reduce the useable volume within the packages.

(3) If in-situ grouting / stirring is required, internal structures need to be avoided or moved as far from the package centreline as possible.

It is considered therefore that the appropriate approach is to provide either a second lifting assembly design to handle these new packages, or design one that can be adjusted to suit either the existing (SWTC type) or new waste package lift centres.

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Clarification of whether the existing or the new lift centres are to be used would need to be stated as a functional requirement at commencement of the detail design, as this will be a fundamental constraint on the designs.

References 6 and 7 have been reviewed and it is suggested that considering the requirements of these references, there are no insurmountable technical issues that would prevent successful manufacture of these packages.

Views of the General Assembly drawings of the new waste packages for Option#4A can be found in Appendix A and RWMD will be supplied with the associated AutoCAD files.

5.2.7 Transport on existing INS KXA-C Rail Wagon

The ability to transport 2 x Options#4A with the maximum payload has been assessed regards the rail transport. The assessment is based upon the use of the KXA-C rail wagon and includes the requirement of a tie-down frame to enable securing of the RTC’s to the rail-wagon base.

* maximum loaded condition

Fig. 20: Option #4A x 2 on KXA-C Wagon


• Route availability is slightly exceeds the KXA-C design limit.

• The KXA-C currently uses axles rated at 22.5te. At this rating, the wagon has restrictions on use and the mileage it can complete. It is assumed that a similar restriction (slightly more restrictive) would be required for this configuration.

The second point suggests that this RTC cannot currently be transported in pairs. However, it should be noted that this is governed by the assumptions of a maximum RTC mass and an assumed mass of the tie-down frame. If approximately 800kg can be removed from the total, the existing KXA-C could potentially be used to transport 2 x Option#4A.

Another option would be to carry a single RTC on the KXA-C. This in its maximum configuration would give an all-up-weight of 117.1Te + suitable tie-down arrangement (3te


RTC * 2 127.3

Tie-down Frame

1 Est. 3

KXA-C 1 53.5

Total 180.8

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approx). Load per axle in this instance is therefore 120.1/8 = 15.0te/axle. This required axle rating suggests the following;

• Reducing the axle loads would reduce the restrictions on Route Availability (RA)

• Axle centres would remain at 1800mm, therefore maintaining the rail gauge width.

• Reducing the KXA-C gross weight may allow the mileage restrictions to be reduced (FEA analysis required).

The following section reviews the possibility of shortening the KXA-C design by reducing the bed length so that it is sized to transport a single RTC

5.2.8 Transport on ‘Shortened KXA-C’ Rail Wagon

Using the modified reduced length KXA-C from option #1 a single Option 4A RTC was added and then reassessed. Again it has been assumed that the tie-down system could be integrated into the bed of the rail wagon.


RTC * 1 63.6

‘new’ wagon

1 48.2

Total 111.8

*maximum loaded condition

Fig. 21: Option#4A x 1 on ‘Shortened’ KXA-C wagon

The load per axle in this instance is therefore 111.8 / 8 = 14.0te/axle. This suggests the following;

• Reduced axle loads would reduce the restrictions on Route Availability (RA).

• Specifying 18te rated axles (a standard size) would present a substantial cost saving over the 22.5te axles on the KXA-C’s.

• The bed of the wagon could be re-designed to integrate the tie-down system.

A new rail wagon would therefore present some advantages over attempting to carry 2 RTC’s on the same wagon and as stated in 5.1.8, the existence of such a wagon would be subject to further review. It should be noted that a single RTC could still be transported on the existing KXA-C’s, but a tie-down frame would be required (i.e. a single version of the one discussed briefly in Section 5.2.7).

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5.2.9 Interface at a Geological Disposal Facility (GDF)

At this point of its development, the maximum mass of the Option #4A RTC with the heaviest possible waste package is 63.6 tonnes, indicating that it is currently compliant with GDF equipment specifications, which is currently understood to be limited to 80 tonnes. The handling of the package is also generically the same as the SWTC-285 and only requires a nominal increase in head-room during opening of the RTC and removal of the waste packages.

5.2.10 Lifting Review – RTC Body

The following assessment is based upon the scoping calculations provided in Section 6.2 of RWE Solutions Document TR/21238/001 and assumes the RTC body material is CA6NM.

The lifting point arrangement is the same principle to that shown in Figure 19 of the above reference. The maximum loaded mass of Option #4A is taken to be 63.6te.

It is assumed that the load acts on only 2 of the 4 lift points and an impact factor of 1.3 is applied (BS 2573).


(63600(9.81)) /2 x 1.3 = 406kN.


406000 / 2 x ((75+60)/2) x 34.5 = 87MPa.


SF = 204/87 = 2.38


406000/ 75x90 = 60MPa


SF = 440/60 = 7.3

Therefore, the existing lifting point design for the SWTC-285 could also be integrated into the designs for Option #4A.

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5.2.11 Review of Leak Rates versus SWTC-285

There should be no new issues concerning leak tightness testing with Option#4A. The approximated lid seal length will be 10% shorter (as measured from the 3D SolidWorks CAD model) than the standard SWTC, which will aid leak testing procedures as follows;

a. Reduce permeation losses b. Reduce by-pass leakage c. Reduction in the inter-space test volume

On the basis, there should be no issue with providing a leak test regime for this RTC.

5.2.12 Review of Shielding

This option currently has the previously agreed shielding thickness and the potential volume of the contents is only slightly greater than the standard SWTC.

Consequently, it is considered that the 285mm thickness would provide an acceptable shielding level. Detailed analysis may actually reveal that the geometry of this option may enable a slight reduction in shielding thickness, as the shielding material is on average nearer to the radiation source. Experience has shown that in transport package systems, placing shielding material as close to the radiation source as is possible, i.e. via a close fitting circular waste package, leads to the most efficient use of shielding material.

5.2.13 Manufacturability and Materials of Construction

As per Option#1, Casting Technology International (Cti) were asked to review the proposed geometry of the Option #4A body and provide manufacturing costs and advice on materials of construction. Cti stated that all the technical requirements could again be met, the only difference being a reduction in casting costs to £250k, due to the reduced amount of material. On this basis, this suggests a total cost of approximately £450-650k for a complete RTC of this design. Cti’s suggestion to engage Sheffield Forgemasters Ltd (or a suitable alternative) as soon as possible if this design is to be progressed should be again noted.

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6 Conclusions

This review has identified, through a staged process, two RTC options which could potentially be used in parallel or as a replacement to the existing SWTC designs.

The characteristics of the two options are briefly summarised below;

Option#1

• The width of Option#1 has been maximised on the rail gauge and subsequently cannot be used with the weather protection covers stipulated for the SWTC designs

• Payload increase of 31.5%, maximum RTC mass increase of 18.1% compared to the SWTC-285

• Able to transport all the waste packages / stillages designed for the SWTC’s (and 5x500litre drums in a new stillage)

• Able to transport new, larger capacity waste packages (Larger drums, boxes and 4x750litre drums) – See Section 5.1.5.

• A single RTC could be transported on the INS KXA-C rail wagons (with an interface frame).

• Can be lifted / tied-down in same way as existing SWTC’s

• Meets the stipulated Rail Gauge limits

• Maximum loaded mass is within the GDF design limits for shaft / drift equipment

• RTC dimensional increases will effect handling operations at waste producer sites and at GDF

• Can be manufactured at an estimated total cost of £500-700k / unit

• Impact analysis is required to verify performance in IAEA 9m drop scenario, which is a current technical risk for this RTC option

• More work is required to substantiate the leak tightness requirements of this option

TD/ETS/R/10/206 Rev 0 46

Option#4A

• The width of Option#4A has been maximised on the rail gauge and subsequently cannot be used with the weather protection covers stipulated for the SWTC designs

• Payload increase of 11.1%, maximum RTC mass decrease of 0.6% compared to the SWTC-285

• Of the existing waste packages, option could only carry the 3m3 drum and 4x500 litre drums, with the 500litre drums requiring a new stillage design

• New packages limited to circular designs – See Section 5.2.5.

• A single RTC could be transported on the INS KXA-C rail wagons (with a suitable interface frame) If package mass / tie-down frame can be reduced in detail design, it may be possible to transport 2xRTCs on a single KXA-C

• Can be lifted / tied-down in same way as existing SWTC’s

• Meets the stipulated Rail Gauge limits

• Maximum loaded mass is within the GDF design limits for shaft / drift equipment

• RTC geometric changes will effect handling operations at waste producer sites and at GDF.

• Can be manufactured at an estimated total cost of £450-650k / unit

• Regulatory performance is generally bounded by the performance of the SWTC-285, therefore providing confidence that this design would meet all IAEA regulatory requirements

Option#1 appears to provide substantial advantages as a waste transport option, as it can carry all existing waste packages and a substantial number of viable, larger alternatives. It can also be transported (1 unit per wagon) on the KXA-C rail wagons, if a suitable interface frame is provided. On the negative side, a current unknown is 9m impact performance, the results of which may challenge the current design and reduce its apparent transport effectiveness. However, this problem may be surmountable by better use and number of lid bolts, which may minimise any effect on capacity.

Option#4A provides a package which is actually lighter than the SWTC-285 and this and its geometry suggests that this design should satisfactorily meet all IAEA test requirements. It could also be moved on the KXA-C rail wagons and a slight mass reduction (which would become apparent following detailed design) may allow two RTCs of this design to be

TD/ETS/R/10/206 Rev 0 47

transported on a single KXA-C wagon. However, the ability to transport existing waste packages is greatly reduced and new waste package options are limited.

In conclusion, INS suggests that further work be focused on analysing the impact performance of Option#1, as this RTC (as currently designed) provides much greater scope in terms of its transport flexibility. This work should also clarify the full range of suitable materials for the RTC body and review the technical aspects of the manufacturing route in more detail. Further work to investigate the ability of this RTC (and its new waste packages) to satisfy regulatory leak tightness requirements is also recommended.

This further review could also encompass its access and interfacing with waste producer sites and a Geological Disposal Facility.

RWMD also need to assess the feasibility of using 8 axle rail wagons and resolve whether a cover is required to meet stakeholder expectations.

The table overleaf summarises the findings for the two RTC options.

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7 References

[1] TD/ETS/R/09/201 - RWMD ‘SWTC’ Size Review – Results of INS Brainstorming Meeting. I.A.Grainey. International Nuclear Services. November 2009.

[2] IAEA TS-R-1 – Regulations for the Safe Transport of Radioactive Material. IAEA Safety Standards.

[3] RSSB GE/GN8573 – Guidance on Gauging. Section 9.3, Calculations on Width Reduction (Vehicles)

[4] 123787-07 – Structural Analysis of the SWTC-285 in the Enhanced Water Immersion Test. Over Arup & Partners. March 2009.

[5] Atlas steels website: http://www.atlasmetals.com.au/Stainless_Steel_Plate.asp.

[6] TWI Report No.13451/1/02 (Nirex Ref. No#388940) Best Practice Guide – Welded Joint Design and Manufacture for Stainless Steel Containers. April 2002.

[7] Nirex Report No: N/070 Waste Container Design – An Engineering Guide for Designers. February 2003.

[8] TD/ETS/R/09/202 - RWMD ‘SWTC’ Size Review – The Development of Six (6) Reusable Transport Container (RTC) Options. I.A.Grainey. International Nuclear Services. February 2010.

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8 Appendix A – Drawings of the Options and ‘new’ Waste Packages

TD/ETS/R/10/206 Rev 0 48

SWTC (ref) Option#1 Option#4A Comments

Unladen mass (kg) 52000 59800 50300 -

Laden mass (kg) 64000 75600 63625 Maximum configuration mass indicated

Cavity volume (m3) 4.31 5.52 4.66 Uses internal height measured to underside of container lid

Carry 3m3 box? Yes Yes No Option #4A – cavity clash

Carry 3m3 drum? Yes Yes Yes -

Carry 4x500 litre drums?

Yes Yes Yes

(but requires a new stillage)

Option#4A will require a circular stillage to carry 4x500

litre drums

Carry 5x500 litre drums?

No Yes No -

Additional waste packages that can

be transported:

0 New maximised square box

New maximised round drum

New 4x750 litre drums in stillage

New maximised round drum (for solid wastes)

New maximised round drum (for liquid wastes)

Option#1 has greatest flexibility regards transport of

new types of waste packaging

Transportable on a 4-axle rail wagon?

Yes No No Options #1 & #4A require an 8 axle wagon due to total mass

Table 4: Summary of the RTC Performance Criteria compared to SWTC-285

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9 Appendix B – INS Report TD/ETS/R/09/202 Rev 0


1

I.A.Grainey. Engineering & Package Approvals. February 2010

Description:

This report captures the technical review of initial concepts for a Reusable Transport Container (RTC). The main objective of the study at this stage is to maximise the useable volume of the RTC as far as is possible, whilst remaining within the physical limitations of the identified rail gauge.

Option #1 on W6a Rail Gauge

Revision and Status Prepared Checked Approved

Revision 0 Signature: Print Name: I. A. Grainey M.Ridley P.Purcell Date: Revision 1 Signature: Print Name: Date: Revision 2 Signature: Print Name: Date: Revision 3 Signature: Print Name: Date:

TD/ETS/R/09/202

RWMD ‘SWTC’ Size Review – The Development of Six (6) Reusable Transport Container (RTC) Options


2

Revision Record

Revision Section Description 0 - First Issue


3

Contents

1 Executive Summary ........................................................................................................... 4 2 Introduction......................................................................................................................... 5

2.1 Preamble ................................................................................................................... 5

2.2 Packaging Requirements........................................................................................... 5

2.3 Transport Requirements ............................................................................................ 5

2.4 Principles of the Review............................................................................................. 8

2.5 RTC - Materials of Construction................................................................................. 8

2.6 Manufacturability........................................................................................................ 8

2.7 Content Activity Limits................................................................................................ 9

2.8 Weather Protection .................................................................................................... 9

3 Options Review ................................................................................................................ 10

3.1 Option #1 – Increase ‘SWTC’ as far as possible in X-Y-Z planes............................ 10

3.2 Option #3 – Cylindrical Package ‘Irradiated fuel type’. ............................................ 15

3.3 Option #4A and #4B – Short Cylinder (or polygon), vertically loaded...................... 20

3.4 Option #5 – ‘Stretched’ SWTC................................................................................. 26

3.5 Option #9 – Reconfigure SWTC Lid retention (3 potential methods)....................... 30

3.6 Option #10 – Design a Package with removable inserts for shielding. .................... 37

4 References ....................................................................................................................... 41 5 Appendix A – General Assembly Drawings of Options .................................................... 42 6 Appendix B – RTC Lifting Points: Scoping Calculations .................................................. 51 6.1 Package Lifting Points – Cuboid RTC Options (excluding Option #9)............................... 51 6.2 Package Lifting Points – Option #3 and Option #9............................................................ 52


4

1 Executive Summary

This study reports on the technical positives / negatives of six RTC options that where identified as the most suitable to progress in an internal (to INS) brainstorming meeting.

At this stage, the study has concentrated on the ability to physically increase the waste transport capacity as far as possible, whilst ensuring the RTC remains compliant with the stated rail gauge and rail-wagon axle limits. It should be noted that no changes have been made to the amount of shielding available to the SWTC (i.e. 285mm of steel) during these initial studies.

Each option has also been reviewed in respect of operational requirements and comments included regarding perceived RTC performance when subjected to regulatory (IAEA TS-R-1) accident conditions.

The content of this report will be discussed at a review meeting with RWMD, where the two options which perform best against identified parameters will subsequently be developed further by INS.


5

2 Introduction

2.1 Preamble

The objective of this study is to establish whether a Reusable Transport Container (RTC) with a higher payload than the current SWTC-285 design is technically viable, whilst remaining compliant with the functional requirements that have been set out and agreed with the Client in Ref. 1. The review focuses on increasing the volumetric capacity of the RTC beyond that of the SWTC-285, thus enabling similar increases in the volumes of the waste packages transported (i.e. the current 3m3 boxes, 3m3 drums and 500litre drums in stillages, etc) for subsequent disposal in the Geological Disposal Facility (GDF). A volumetric increase in the amount of waste per transport package will increase the cost effectiveness of waste transport and potentially of storage also.

This report captures the technical review completed on the six best options previously identified in an internal (to International Nuclear Services) brainstorming meeting (Ref. 12). A workshop review with RWMD will then select two options that will be progressed in more detail. The findings will be captured in a further report. In parallel to this RTC development work, the revised waste packages which these two options would transport will also be developed.

2.2 Packaging Requirements

Each of the RTC options shall be assessed against the requirements of a B(M) package as is described in the Regulations for the Safe Transport of Radioactive Material (TS-R-1). Engineering judgement and previous knowledge of transport package design will be employed by the INS project team to review each option against regulatory accident requirements, e.g. impact, fire, etc and good engineering design principles. These views shall be captured in the individual option descriptions in the following sections of this report.

2.3 Transport Requirements

The development of six RTC options has been progressed on the premise that transport will be primarily by rail, with each option being required to satisfy the rail gauge and Route Availability (RA) requirements stipulated in the Functional Specification (Ref. 1). Any road transports would be classed as abnormal loads and as such, would be subject to the relevant legislative restrictions / requirements.

To maximise the working volume of the RTC, the combined mass of the container and the rail wagon are an important limiting parameter. Reasonable assumptions therefore need to be made regards the rail wagons self weight and the total i.e. the Gross Laden Weight (GLW) of the rail transport, based upon the axle load limits captured in Ref. 1.

As an example; for the existing SWTC design, the total mass (and hence, the available container working volume) has been based upon the assumption that a 4-axle rail wagon


6

would weigh approximately 26te (Ref. 2) and that the GLW of the SWTC, combined with the rail wagon needs to remain within the identified axle limits.

Reviewing the combined mass of the loaded SWTC and the rail wagon, it is evident that any appreciable increase in package mass beyond that of the SWTC will quickly exceed the identified axle load limits for a four axle wagon and necessitate an increase in the required number of axles.

The next logical step beyond a 2 bogie / 4 axle wagon would appear to be a 2 bogie / 6 axle wagon. However, discussions with NetWork Rail designers (Ref. 3) suggest that the use of 3 axle bogies should be avoided, with the following reasons being provided;

• There are no 3-axled rail wagon bogies in use on the UK rail network

• Long lead times are to be expected, due to the ‘non-standard’ bogie design and the need to programme work into ‘standard’ wagon manufacturing runs

• Existing use of such bogies appears to be restricted to Germany. However, the NetWork Rail contact commented that there appears to be regulatory concerns there over the poor ride performance of these bogies

• The NetWork Rail contact also suggested that the intermediate wheel-set ‘…will tend to hinder progress along curved track sections, leading to unstable wagon dynamics…’

• The implied reduction in axle centres is not good for UK Route Availability (RA), as there will tend to be localisation of loads, leading to speed restrictions not required on 2-axled bogies

Due to these issues, the INS team discounted the 3 axle bogie as a viable option. The natural progression after this is to double the number of ‘standard’ bogies (i.e. each having 2 axles) to arrive at a design of an eight axle rail-wagon. This bogie configuration is acceptable on the UK rail network and INS has recently taken delivery of six such wagons for ‘high mass’ package transports. As the individual axle load sharing capability of an eight axle wagon is increased substantially over a four axle wagon, it also provides the opportunity to possibly down-rate the individual axle capacities (which are the components of greatest expense on a rail wagon) and therefore provide possible cost savings. However, due to the length of the wagon and track over-throw issues, the available width at the centre of the wagon is reduced over the standard W6a gauge and this needs to be taken into account when assessing the useable gauge width and hence, the width of the RTC options.

Throughout the following assessments, each option has been assessed to identify whether a four or an eight axle rail wagon is required*. This will ensure that both total mass and dimensional considerations are realistically assessed. For the four axle rail wagon, Ref.4 has been used to provide bounding case dimensions and masses. Similar information for an


7

eight axle rail wagon are derived from the wagons owned and operated by INS (Ref. 5, 6) which are believed to be the largest available.

It should be noted that the majority of the options (at this stage of the assessment) use the tie-down methodology suggested for the SWTC (as this method negates the need for separate transport frames) and therefore any new 8-axle rail wagons would need to incorporate the interfacing tie-down mechanisms indicated in Ref. 4.

* Note: All the proposed options will require an 8-axle wagon based upon the axle limitation identified. As stated earlier, it is evident that the current SWTC has been maximised as far as possible in respect of the limits for a 4-axle wagon.

Taking this into account and using the actual dimensions of the INS 8-axle wagons, the overall length of the wagon means that the over-throw at the centre is greater than the shorter 4-axle wagon, which leads to a reduction in the working width of the required W6a rail gauge. This reduction in available width is shown in the following figure.

Standard W6a Rail Gauge and the Reduced Gauge due to wagon over-throw

Although the study has therefore used this reduced width version of the rail gauge, the RTC width increases remain appreciable and as the options show, provide substantial increases in transport capability. When the two most suitable options have been selected, a review of the length of the 8-axle wagon (i.e. shortening it to suit the selected options) could increase the gauge width available to the selected options.


8

2.4 Principles of the Review

Following the description of each option in the following sections, the INS team have identified a number of pro’s / con’s which they judge applicable to the individual option reviewed. External input has been sort and recorded on manufacturing techniques for the package bodies, but in general, the findings are based upon the INS teams engineering judgement; i.e. knowledge of previous transport package designs and the response of these to analytical and physical test scenarios.

The size increases the six options provide are indicative only at this stage and are based upon the rail gauge restrictions, total transport mass (i.e. including the rail wagon), existing shielding requirements (285mm of steel) being maintained and some assumptions on regulatory performance. Any actual increases would be subject to, for example;

• Future analysis on impact performance, which indicates a requirement to increase the size / geometry of the shock absorbers. As appropriate to the options recorded in this report, shock absorbing geometry has been increased using a linear comparison to the existing SWTC design. Increasing the size of the shock absorbers due to further analysis would effectively decrease the size of the proposed RTC and possibly reduce the apparent attractiveness of the option. This current unknown needs to be born in mind during the selection workshop.

• Future shielding analysis, which indicated an increase in shielding thickness, (currently 285mm of steel) due to the increased waste in the transported packages. Self-shielding effects are anticipated from the additional waste, but some of the volumetric increases are significant and may require further increases in shielding. This will affect the overall mass and capacity due to the implied cavity size reduction.

2.5 RTC - Materials of Construction

In each instance, the material review will concentrate on the RTC body, as this is the component of highest cost, longest lead-time and is obviously critical to the RTC performance in both normal and accident regulatory conditions. The material specified for the SWTC body is CA6NM. This is a castable stainless steel material with excellent ductility, impact properties and apparent good corrosion resistance to sea water. It can be cast into both intricate and thick-wall sections and can also be welded, although this could change material properties and should be avoided if possible.

This material will also be considered for the RTC options developed, as applicable. Other suitable materials will also be considered and these will be discussed in the individual assessments.

2.6 Manufacturability

No concept design option can be deemed viable unless a scoping review has assessed whether the design proposal can actually be manufactured. The design options have therefore been assessed, concentrating again upon the ability to manufacture the body of the RTC options in suitable materials. The lid is also a critical component, but this will be a simpler item


9

to manufacture and is not assessed at this stage. This report concentrates on the ‘theoretical’ ability to manufacture the RTC body, using proven methods, within the UK or overseas. The second report that shall investigate the 2 selected options in greater detail will revisit manufacturing requirements and expand this to the main sub-assemblies of the two RTC options and their waste packages.

Regards the clearance between the RTC inner walls and the waste packages transported, the clearance dimensions suggested in Ref. 8, Section 3.3 have been consistently applied to ensure that manufacturing tolerance variations and loading requirements at waste sites and at the GDF are accounted for.

2.7 Content Activity Limits

By increasing the working volume of the RTC, the waste packages and subsequently the amount of waste transported can likewise increase. This leads to similar increases in both content activity limits and total thermal output.

The descriptions of waste packages and configurations of packages in Ref. 7 indicate that the activity content of a SWTC transport should not exceed 105A2 and the thermal output should be limited to 200W, with the transported waste package output reducing to 150W at the point of GDF back-fill (indicated in Ref. 7 as occurring in 2090). These important limits will be discussed in more detail in the report which reviews the two selected options.

2.8 Weather Protection

It should be noted that the options studies have maximised the width of the RTC options at the expense of the weather protection provided for rail transport for the SWTC designs i.e. the retractable covers on the rail wagon. However, it has been assumed that the advantage of removing these covers outweighs the disadvantages, in that waste transport capacity is greatly increased only at the expense of weather protection. The lack of protection from the elements is not seen as a major issue, as there is a precedent for RAM package transports (Magnox, AGR, Irradiated Fuel transports) without weather coverings. The use of stainless steels (or if required, maintained paint finishes on carbon steels) would ensure that package material and importantly, package appearance will not deteriorate over the packages working life. The only potential issue to address is water ingress / pooling in the lid area of vertically lidded options in the event of rain. This potential issue could be countered by providing a suitable light-weight ‘weather cover’ for the RTC which would be removed (possibly manually) prior to RTC handling. Such a cover is discussed in the review for Option #1.

The following sections review each of the options. A general arrangement drawing of each option can be found in Appendix A.

TD/ETS/R/09/202 Rev 0 10

3 Options Review

3.1 Option #1 – Increase ‘SWTC’ as far as possible in X-Y-Z planes.

Using the W6a rail gauge as the dimensional limits for the RTC width and height (and assuming the length remaining equal to the new width), the existing design of the SWTC-285 has been inflated in the X-Y-Z planes to arrive at the geometry as depicted in the figure above.

The configuration of this option is identical to the SWTC and therefore the general method of operation would be the same, notwithstanding the substantial increase in masses to be handled.

The option provides a useful increase in payload from 12te to nearly 15.5te. However, this may have implicit safety implications if there is not a corresponding enhancement in impact performance. Some basic changes have been made to the size of the shock absorbing structures to account for this increase, but the performance of these will require impact analysis to provide greater understanding of its response. Such impact analysis may also reveal challenges to the lid retention system and the associated sealing arrangements.

TD/ETS/R/09/202 Rev 0 11

The payload increase would also influence internal pressure generation which could also affect the design, but this is seen as unlikely.

The tie-down method for the SWTC-285 has been included in this option and no major problems are envisaged with ensuring this system could meet the requirements of IAEA TS-R-1 transport accelerations.

A potential benefit of the increased payload and overall mass of this option are possible marginal improvements in the RTC response to the fire accident case, which may provide opportunities to reduce and / or simplify the method of thermal protection currently incorporated in the SWTC.

Regards the issue of weather protection discussed in Section 2.8, the following sketches indicate how the idea of a ‘weather cover’ could be implemented. This concept is also generally applicable to Options #4, #5, #9 and #10.

Weather Cover shown above RTC

Weather Cover shown in position on RTC

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Each of the options would carry waste packages of differing geometry and mass, based upon the cavity size and these attributes are compared with the relevant SWTC-285 figures in the comparison tables in each section. However, to provide a visual bench-mark of the increase of the RTC cavity, the following diagram is also provided, showing the number and configuration of 500 litre drums the RTC option could transport. This simple bench-marking technique is repeated for each option.

5 x 500 litre drums in Option #1 Cavity

As the bounding case for ‘cuboid’ type options in respect of size and mass, the body of Option #5 has been investigated to ensure the technology is available to allow manufacture using materials which have the necessary mechanical properties. Discussions with external experts (Ref. 10, 11) have indicated that the Option #5 body could be successfully manufactured and it is therefore assumed that this option which is dimensionally smaller and lighter in mass is also viable.

Handling of the option is assumed to be in the same manner as the SWTC-285 and scoping calculations (Appendix B, Section 6.1) indicate that the existing lifting methodology could be integrated into this increased mass option.

The geometry / mass comparison with the SWTC-285 is provided in the table overleaf.

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Option #1 RTC:

RTC Option 1 Comparison with SWTC-285



Overall Width (mm) 2410 2670 + 260 mm

Overall Length (mm) 2410 2670 + 260 mm

Internal Volume (m3) 4.31 4.95 + 14.7 %

Container Mass (kg) 52000 63850 +11850 kg


Approx. Total Volume (m3) 3.7 4.5 + 21 %


Combined Mass (kg)


64000 79300 + 14700 kg

4-axle wagon

(self weight est. = 26000kg)

8-axle*


Rail Wagon Type required for Option, based upon;

(Combined Mass) / No. of axles <

22.5te

x !

* assuming axle load is evenly distributed, load per axle is approximately 16.5te. This provides some cost saving opportunities, due to possibility of down-rating the wagon axle units.

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The following table captures the INS team views of Option #1 RTC.

Option #1 – INS Identified Advantages / Disadvantages

Pro’s Con’s

• Substantial increase in working volume (see Table above)

• Identical configuration as the SWTC, therefore operating methodology also the same

• Increase in mass suggests response to regulatory thermal loads may be improved

• Can accommodate existing waste packages with appropriate interfacing.

• Increased mass / geometry may challenge facilities available at waste sites

• Requirement for 8 axle rail wagon

• Response to impact probably compromised to some degree due to higher mass and reduction in relative stiffness in comparison to the SWTC

• Potential to easily jam lid during normal operations due to lid/body interface and integrated shock absorber design (however this comment also applies to the SWTC)

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3.2 Option #3 – Cylindrical Package ‘Irradiated fuel type’.

As with Option 1, the width of the option has been maximised in relation to the rail gauge and its length in relation to the wagon length, but in this instance the RTC body width is restricted by the shock absorbers that are required for this option. This concept is based upon the well proven ‘spent fuel flask concept’ and offers a significant increase in payload which would require the use of an eight axle rail wagon. The indicated carrying capacity is increased to 28te; this may also require an increase in the shielding requirements subject to further review, with the potential to reduce the payload increases stated here.

The significantly increased payload will also potentially lead to increases in pressure build-ups within the RTC cavity, but this is not seen as significant, particularly taking into consideration the fact that the cylindrical cross-section will inherently improve the ability to contain hydrostatic loads.

However, the total mass of this option (>100te) may bring significant challenges to waste sites in relation to both RTC handling and floor loadings.

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Loading operations for this RTC option are envisaged to require tilting the package from the horizontal (transport mode) into the vertical (loading / unloading mode). This will require more ancillary equipment than the other options e.g. tilt frames, access platforms, shock absorber lifting kit, set-down stillages, etc and hence the amount of general operational stages will increase in relation to the other options. Handling of this option is assumed to be via hollow lifting trunnions on the RTC body and scoping calculations (Appendix B, Section 6.2) indicate that this lifting methodology would be deployable on this option.

An alternative to vertical loading is to integrate a ‘skid’ loading system into the RTC body which would enable it to be loaded whilst in the horizontal. Although this is seen as feasible from a technical perspective, it would increase the internal complexity of the RTC and its handling, hence also costs, whilst reducing the useable cavity volume and potentially increasing the chance of technical issues / potential failures. Lid fitment and sealing would also be more challenging in the horizontal orientation.

As indicated in the diagram above and the drawing in Appendix A, the option currently integrates the tie-down methodology indicated for the SWTC-285. These features would be bolted to the main body and are hollow to ensure their collapse in a regulatory impact and limit the magnitude of the forces acting upon the RTC body. The alternative is to provide a separate transport frame, which would impact the overall transported mass. This would use a dedicated diameter on the lifting trunnions to tie-down the RTC to the transport frame and hence to the rail-wagon. Although this is another item of equipment this particular option requires, the use of transport frames is a well understood method of package tie-down and technical design issues would be minimal.

Regulatory performance of this option can again be gauged against known irradiated fuel flask designs and the provision of wood filled shock absorbers would suggest both good impact resistance and seal protection during the fire accident scenario is achievable. The option as indicated also incorporates a ‘bayonet’ type lid which reduces reliance on lid bolting to maintain containment by placing more reliance upon the lid / body interface. This type of lid bayonet system has been successfully used on a recently licensed INS B(U)F transport package and it has proven to be successful both in a regulatory sense and in reducing lid securing times.

The circular cross-section of this option and the lid position during transport (in addition to the lid shock absorber) negates the need for weather protection.

A potential draw-back of this idea is that to take full advantage of the useable RTC cavity volume, the waste packages it transports would all be circular in cross-section and hence the efficiency of storage volume within the GDF may be in question.

The 500 litre drum capacity assessment is captured in the images overleaf, showing that 6 such drums could be transported in this RTC.

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In respect of manufacture, the geometry of this RTC body is similar to the INS ‘Excellox 6’ package body which is a licensed Type B(U) package used for transport of spent fuel. This package body is forged and is manufactured from ASTM A350(M) Grade LF5 Class 1 carbon steel, which has excellent mechanical and impact properties at both ambient and sub-zero temperatures. The Excellox 6 has a painted external surface and is internally clad with stainless steel, which could also be incorporated into this option.

Alternatively, discussions with the Casting Technology Institute - CTI (Ref. 9) indicate that with minor design modifications required during casting (which could subsequently be machined away) the body could be cast in at least two suitable stainless steel materials which have the required mechanical properties.

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Option #3 RTC:



Overall Height (mm) 2175 2600 (dia) + 425 mm

Overall Width (mm) 2410 2600 (dia) + 425 mm


Internal Volume (m3) 4.31 9.82 + 128 %

Container Mass (kg) 52000 80850 + 28850 kg




Combined Mass (kg)


64000 108850 + 44850 kg

4-axle wagon


8-axle*




22.5te

x !

* assuming axle load is evenly distributed, load per axle is approximately 20.2te.

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Option #3 – Identified Advantages / Disadvantages

Pro’s Con’s

• Large cavity volume

• ‘Proven’ design type

• Could carry existing 500 litre drums

• Response to regulatory accident conditions likely to be improvement over ‘cuboid’ designs

• More complex handling

• More ancillary equipment

• High mass

• Cannot carry 3m3 box or drum

• Very different from current design, therefore possibly ‘high impact’ design for interfacing with the waste producing sites

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3.3 Option #4A and #4B – Short Cylinder (or polygon), vertically loaded.

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This option has been divided into two sub-options which have different potential benefits. Each is described separately;

Option #4A is a circular, top loading RTC with its diameter maximised in relation to the rail gauge. The body shape will be relatively easier to manufacturer in comparison with the ‘cuboid’ options and the containment sealing system should also be simpler to implement.

The benefits of this sub-option are probable marginal performance improvements in impact and fire accident conditions in relation to cuboid options. However, the option obviously does not lend itself to the transport of square waste packages and these couldn’t realistically be moved in this RTC, although four 500litre drums could still be transported in a revised stillage, indicated in the image below.

4 x 500 litre drums in Option #4A Cavity

Assuming use of the circular cavity is maximised with a larger version of the existing 3m3 drum, the gross mass of the transported waste package is increased from 12te to 15te (+25%).

Option #4B is a variant of #4A and is based upon a hexagonal cross-section body and a similarly profiled lid. The main assumed benefit of this variant is seen to be the ability to storage the associated ‘hexagonal’ waste packages in the GDF with minimal ‘dead space’ in comparison to #4A’s circular waste packages, whilst being an RTC which should have marginally improved strength and hence impact performance over the ‘cuboid’ RTC options.

In addition, as this RTC would be transported with its minimum width (across flats) perpendicular to the axis of travel, the geometry means that its depth along the wagon (across corners) is greater and this would provide a nominal increase in waste transport capability. Notwithstanding these potential advantages, the body / lid geometry will bring additional manufacturing challenges.

TD/ETS/R/09/202 Rev 0 22

Storage provision for the 500 litre drums for this sub-variant is provided in the image below.

4 x 500 litre drums in Option #4B Cavity

Both #4A and #4B could be manufactured from the same cast materials as the SWTC-285, although the hexagonal version may provide more challenges. The discussions with the Casting Technology Institute (CTI) surrounding the bounding case size / mass of Option #5 would suggest that these options’ bodies could also be successfully cast in appropriate materials.

The variants indicated currently utilise the same tie-down methodology identified on the SWTC-285.

TD/ETS/R/09/202 Rev 0 23

Options #4A and #4B RTC are summarised in the following two tables:

RTC Option 4A Comparison with SWTC-285



Overall Width (mm) 2410 2690 (dia) + 280 mm

Overall Length (mm) 2410 2690 (dia) + 280 mm

Internal Volume (m3) 4.31 4.12 - 4.4 %



Approx. Total Volume (m3) 3.7 3.75 + 1.4 %


Combined Mass (kg)


64000 66350 + 2350 kg

4-axle wagon


8-axle*




22.5te

x !


TD/ETS/R/09/202 Rev 0 24

RTC Option 4B Comparison with SWTC-285



Overall Width (mm) 2410 2670 (A/F) + 260 mm

Overall Length (mm) 2410 2982 (A/C) + 572 mm






Combined Mass (kg)


64000 70950 + 6950 kg

4-axle wagon


8-axle*




22.5te

x !


TD/ETS/R/09/202 Rev 0 25

Option #4A – Identified Advantages / Disadvantages

Pro’s Con’s

• Relatively simple manufacturing

• Simpler seal arrangement

• Improved impact performance

• Can carry 4 x 500 litre drums


• Waste packages it can transport will reduce storage in GDF

Option #4B – Identified Advantages / Disadvantages

Pro’s Con’s


• Bespoke waste package (hexagonal) will have good storage use in GDF


• Probably more difficult to manufacture than Option #4A

• Reduced impact performance compared to Option #4A (but better than cuboids)

• Hexagonal waste package has increased manufacturing issues than circular / square versions

TD/ETS/R/09/202 Rev 0 26

3.4 Option #5 – ‘Stretched’ SWTC.

This option again maximises the width of the RTC based upon the rail gauge in the same manner as the previous options, but utilises the available space along the axis of travel to elongate the RTC. In this way, the useable capacity of the RTC has been greatly increased, but clearly, this also increases beyond that of Option #3, without having the structural integrity of that options cylindrical body design.

The performance of this particular option in an impact situation is the major question in respect of its regulatory performance; the integrated shock absorbers as indicated are unlikely to be sufficient in absorbing the impact forces and the inherent reduction in body and lid stiffness in comparison with the SWTC will probably mean that the containment boundary will be severely challenged, particularly in a ‘slap-down’ orientated impact. Similarly, the large flat surfaces of this option will mean the package is subjected to large heat fluxes during the fire accident conditions that would lead to substantial thermal stressing effects, again possibly leading to a lid containment breach.

However, putting these significant issues to one side for a moment, the storage provision of this option is its central asset and is an appreciable increase over the SWTC-285. This is made clear in the potential storage provision for 500 litre drums in the following image.

TD/ETS/R/09/202 Rev 0 27


This option represents the ‘bounding case’ in respect of size and mass for the cuboid RTC options and as such, the ability to manufacture the body of this RTC has been investigated with external suppliers. Discussions with the Casting Technology Institute - CTI (Ref. 10) and Corus (Ref. 11) indicate that with minor design modifications (i.e. draft angles) the body could be cast in a suitable stainless steel material which has the required ambient and sub-zero mechanical properties.

However, the CTI also stated that the ability to manufacture a casting of such a mass is probably limited to only three producers world-wide who have the capacity to produce this. The CTI quoted costs in the order of £600-650,000 to manufacture this body in a European facility, exclusive of NDT requirements and subsequent machining costs.

TD/ETS/R/09/202 Rev 0 28

Option #5 RTC is summarised in the following table:






Internal Volume (m3) 4.31 9.35 + 117 %

Container Mass (kg) 52000 93900 + kg




Combined Mass (kg)


64000 124250 + 60250 kg

4-axle wagon


8-axle*




22.5te

x !

* assuming axle load is evenly distributed, load per axle is approximately 22.1te.

TD/ETS/R/09/202 Rev 0 29


Pro’s Con’s

• Very large capacity increase

• Can carry 8 x 500 litre drums or 2 x 3m3 boxes or drums

• Impact performance highly questionable without additional lid bolts and additional shock absorbers

• Fire accident performance probably poor

• Challenge to waste producing sites regards its mass and handling

• Most expensive from manufacturing perspective

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3.5 Option #9 – Reconfigure SWTC Lid retention (3 potential methods).

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The main objective of this option was to maximise the RTC in a similar manner as Option#1 (i.e. dimensional increases in X-Y-Z planes) but also to further enhance the vertical useable volume by reconfiguration of the lid fixing method. The manner in which this has been addressed is to remove the integral shock absorbing features on the RTC body and lid.

However, removing these features places even greater reliance on the body / lid interface and new lid securing methods need to be devised which would ensure the lid is still retained in an impact when these energy absorbing structures are not present.

Three potential methods of achieving this have been identified*, and these are captured in this section so their relative merits can be compared. Each of these methods of lid retention could potentially be applied to a number of the other options.

*The number of methods identified here is not exhaustive and is meant as a guide to indicate that some gains may be achievable if the lid retention method is modified. Any revisions will need further detailed review and impact analysis to indicate if there are any real benefits to be gained.

A further issue of this option is that by removing the integral shock absorbers, the lifting method for the SWTC and the ‘cuboid’ options is lost. For this reason, Options #9A, #9B and #9C employ two hollow lifting trunnions for lifting operations which during transport would be

TD/ETS/R/09/202 Rev 0 32

orientated along the axis of rail travel, to ensure their depth does not effect the width of the package in relation to the rail gauge. The use of such trunnions for lifting the RTC is bounded by the assessment for Option #3 captured in Appendix B, Section 6.2.

The following descriptions of the three sub-options concentrate on the revisions to the body / lid interface.

Option #9A has a lid which operates by sliding (horizontally) through an aperture of the RTC body and when in position, is bolted down to energise the containment seal. An analogy for this type of mechanism is a ‘Gamma Gate’ system and the presumed advantage of this for the RTC is that the ability to maintain containment in regulatory accident conditions is reliant upon the integrity of the RTC body / lid materials and less reliance is placed upon lid bolt performance. However, although this idea appears to be technically feasible, there are a number of apparent issues surrounding the reliability of such a mechanism under such high loads in a restricted space i.e. wear issues, the substantial turning moments acting upon the lid when retracted and the possibility of lid jamming at any stage of engagement. Operation of the lid would also require additional ancillary equipment. These issues could be addressed to some degree by re-orientating the package and loading it in the horizontal with the lid now moving in the vertical, but this then leads to issues with how the package is placed within the RTC cavity.

Option #9B repositions the lid securing bolts to act through the RTC body and load the lid at an angle of 45°. This system provides the means of lid seal compression and also a more secure body / lid interface during a regulatory impact. This improvement is due to the integrity of the connection having greater reliance on the body material and also that the securing bolts are subjected to compression and limited bending stresses, rather than the high tensile forces seen in the conventional lid bolting system. A potential draw-back of this option is the requirement to thread the bolt holes in the RTC body, but this is seen as feasible and these holes would also be heli-coiled to ensure the female threads could be maintained. However, there is a risk of the bolt heads deforming under the closure load and reducing the closing force. This may occur due to the relative low strain energy in the bolt, resulting from its small effective length. This effect could also become apparent when the package is subjected to the thermal accident conditions leading to thermal strains.

Finally, Option #9C aims to improve the impact resistance of the RTC body / lid interface by separating the containment and impact resistance systems. This would be achieved by providing two separate lids. The inner lid would carry the seals that provided the containment boundary, whilst the upper lid would be the impact limiter and is not envisaged to carry seals. The final configuration of this two lid system would be subject to analysis, but the concept of isolating the containment and impact resistance systems from one another is a technique which exists on other licensed designs, e.g. the INS M4/12 Type B(U)F package.

The useable volume of this option is identical to Option #1 and therefore these options could also carry 5 x 500 litre drums.

These options are physically bounded in size by Option #5 and therefore the bodies can be cast in suitable materials.

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Option #9 RTC’s are summarised in the following tables:

RTC Option 9A Comparison with SWTC-285










Combined Mass (kg)


64000 80150 + 16150 kg

4-axle wagon


8-axle*




22.5te

X !


TD/ETS/R/09/202 Rev 0 34

RTC Option 9B Comparison with SWTC-285


Overall Height (mm) 2175 2115 - 60 mm








Combined Mass (kg)


64000 82450 + 18450 kg

4-axle wagon


8-axle*




22.5te

X !


TD/ETS/R/09/202 Rev 0 35

RTC Option 9C Comparison with SWTC-285


Overall Height (mm) 2175 2092 - 83 mm








Combined Mass (kg)


64000 75100 + 11100 kg

4-axle wagon


8-axle*




22.5te

x !

* assuming axle load is evenly distributed, load per axle is approximately 16te. This provides some cost saving opportunities, due to possibility of down-rating the wagon axle unit.

TD/ETS/R/09/202 Rev 0 36

Option #9A – Identified Advantages / Disadvantages

Pro’s Con’s

• Increase cavity over Option #1

• Lid retention has more reliance on body material than lid bolts

• Lid bolt torques will probably reduce

• Complex, unproven lidding arrangement

• Potential lid jamming issues

Option #9B – Identified Advantages / Disadvantages

Pro’s Con’s


• Design / operation not dissimilar to normal method of lid bolting

• Possible improvements in impact scenario

• Female threads in body require maintenance

• Any bolt deformation will greatly reduce force acting upon containment boundary seal

Option #9C – Identified Advantages / Disadvantages

Pro’s Con’s


• Advantage of isolating impact resisting and containment systems

• More complex to fit and secure lids

• More time consuming to fit lids

• Difficulty in accessing containment boundary test point if in lower lid

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3.6 Option #10 – Design a Package with removable inserts for shielding.

Option #10 investigated whether the RTC could be made into a multiple purpose transport container by reducing the fixed body wall thickness to nominally 150mm (as per the SWTC-150) and using a suitable ‘shielding liner’ as required to provide the same amount of shielding as the SWTC-285.

The potential advantage of this option is that the waste materials requiring the least shielding can be designed to meet the cavity dimensions with no liners present and therefore maximise the waste per transport. Correspondingly smaller waste packages (i.e. with higher surface dose rates) would then be used when the shielding liner is required.

It is proposed that the liner would be manufactured from lead sheets encased in a steel support structure. In this way, the amount of shielding material (i.e. its overall thickness) could be reduced by approximately 20% in relation to a steel only structure and this additional space utilised by the waste packages requiring the higher levels of shielding.

TD/ETS/R/09/202 Rev 0 38

Although this option potentially provides a more flexible RTC design, the main issue surrounds the ability to positively locate and secure the liner within the body and prevent it from adding to the impact forces, particularly during a ‘lid down’ orientated drop. The retention of the liner is proposed to be via a combination of securing bolts and by keying the liner into the RTC body at a number of positions to limit / prevent its acceleration during such an impact.

The ability of this option to transport the 500 litre drums is shown in the image below, which shows the RTC with the liner in position.

5 x 500 litre drums in Option #10 Cavity (with liner)

The size of this options body means that it is bounded by Option #5 and therefore could be manufactured. One potential draw-back is the lead liner; many manufacturers will not work in this material due to toxicity issues and the liners may need to be sub-contracted to a specialist supplier. In addition, the issue of whether the liners can be made to be self supporting within the available space will prove a substantial design challenge.

TD/ETS/R/09/202 Rev 0 39

Option #10 RTC is summarised in the following table (with the liner present):






Internal Volume (m3) 4.31 5.95 (with liner) + 37 %



Approx. Total Volume (m3) 3.7 **5.25 + 41 %


Combined Mass (kg)


64000 78050 + 14050 kg

4-axle wagon


8-axle*




22.5te

x !


** if the liner is not used, the waste package size can be increased to approx 7.3m3 with a mass of 26365 kg and a combined mass of approximately 63te.

TD/ETS/R/09/202 Rev 0 40


Pro’s Con’s

• Can carry 5 x 500 litre drums and the 3m3 box and drum

• Provides a more ‘multi-purpose’ design and waste packages requiring less shielding can be correspondingly larger, to take account of the liners removal

• Use of 150mm casting (or forging) would have cost benefits

• Ability to successfully locate liner to prevent secondary impacts during a lid down impact will be a design challenge

• Structural integrity of liner will be difficult to achieve within available space

• Lead liner toxic – manufacturing and disposal issues

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4 References

[1] TD/ETS/S/09/307 Rev 1 – Technical Specification of a RWMD Reusable Transport Container (RTC) for the transport of Waste Packages. P.Purcell. International Nuclear Services. December 2009.

[2] Nirex Report No N/022 – Foundations of the Phased Disposal Concept. Radioactive Waste Transport.

[3] Correspondence – AFinch.INS.15.12.09 – Record of telephone discussion with Net Work Rail Engineer re: Viability of 3-axle rail-wagon bogies. December 2009.

[4] Drawing T/DRG/20232 E/01 – Rail Vehicle to carry Radioactive Waste packages.

[5] 1298BNFLswan-neckwagonGA.sldasm - Type KXA-C 8 axle rail wagon. 3D solidWorks model. International Nuclear Services

[6] 0/TR/1934577 – KXA-C Swan Neck Rail Wagon, General Assembly Drawing. International Nuclear Services.

[7] Nirex Report N/104 Volume 1 (Issue 2) – Generic Repository Studies. Generic Waste Package Specification. Volume 1 – Specification.

[8] Nirex Report 273089 v1 – SWTC Design Specification. Nirex 1998.

[9] E-mail (2): A.Rowett. Casting Institute 05.02.10 – Technical review of manufacture of #Option 3.

[10] E-mail (1): A.Rowett. Casting Institute 05.02.10 – Technical review of manufacture of #Option 5.

[11] E-mail: B.Crelling. Corus Group 11.02.10 – Technical review of manufacture of #Option 5.

[12] TD/ETS/R/09/201 Rev 0 – RWMD SWTC Size Review Project. Results of INS Brainstorming Meeting, 26.11.09.

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5 Appendix A – General Assembly Drawings of Options

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6 Appendix B – RTC Lifting Points: Scoping Calculations

6.1 Package Lifting Points – Cuboid RTC Options (excluding Option #9)

The following assessment has been bounded by Option #5, as this has the highest mass of the ‘cuboid’ options. The calculation is based upon the scoping calculations provided in Section 6.2 of RWE Solutions Document TR/21238/001 and assumes the RTC body material is CA6NM.

The lifting point arrangement is assumed to be identical to that shown in Figure 19 of the above reference. Loaded Mass of option 5 is approximately 125te. It is assumed that the load acts on only 2 of the 4 lift points and an impact factor of 1.3 is applied (BS 2573).


(125000 (9.81)) /2 x 1.3 = 797kN.


797000 / 2 x ((75+60)/2) x 34.5 = 171MPa.


SF = 204/171 = 1.2


797000/ 75x90 = 118MPa


SF = 440/118 = 3.7

Therefore, the existing lifting point design for the SWTC-285 could also be integrated into the designs for options 5, 1, 4A, 4B and 10.

TD/ETS/R/09/202 Rev 0 52

6.2 Package Lifting Points – Option #3 and Option #9

Option 3 is a fundamentally different design concept and is based upon cylindrical irradiated fuel packages. The option therefore includes hollow lifting trunnions and may also require the supply of a transport frame. This scoping calculation assesses that the size of trunnions indicated are adequate for the RTC option. Trunnions are also required on Option 9, as these would not have the lifting points covered in 6.1. The mass of Option 3 is used as this is the bounding case for options requiring trunnions.

(Note: the approximate mass of a transport frame is also included in the lift as a pessimism)

The loaded mass of option 3 is approximately 109te. 7te is added to this to include the mass of a transport frame. Again, it is assumed that the load acts on only 2 of the 4 lift trunnions (note: Option 9 will only have 2 trunnions) and an impact factor of 1.3 is applied (BS 2573).

Assume trunnion material is martensitic stainless steel - BS 2S 143C.

Load acting on each trunnion diameter is,

(116000 (9.81)) /2 x 1.3 = 740kN.

Shear stress acting upon the resisting diameter of 2 trunnions,

740000 / 2 x (pi(1002 - 902)= 62MPa.

Bending moment acting;

740000 / 2 x 175 = 64.75MNmm

Section Modulus of resisting trunnion section;

Z = 2.31e6 mm4

Bending stress = 64.75 / 2.31 = 28MPa.

Combined stress;

CS = sqrt ((Bending Stress^2 + 3(Shear Stress^2))

TD/ETS/R/09/202 Rev 0 53

CS = 111MPa

Allowable combined stress (to BS 2573 requirements) for trunnion material = 780 x 0.93 = 725MPa

SF = 725/111 = 6.5

Size of trunnions indicated for options 3 and 9 are adequate.

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10 Appendix C – Note of RWMD Workshop

The findings of the options report (TD/ETS/R/09/202) and the associated drawings were presented to RWMD at a meeting on the 16th February 2010 at the Milton Hill House Hotel. The objective of this meeting was to review the six options developed by INS and identify the two options which the attendees considered should be developed further.

The attendees reviewed the individual pro’s / con’s INS had identified in Ref. 8 to see if they were correct and whether more could be identified. The additional findings recorded during the meeting are provided below;

Additional Pro’s / Con’s of the 6 Options

The SWTC was reviewed first as a bench-mark for the six RTC Options.

SWTC

Pros Cons

• Consistent with all current packaging proposals

• Consistent with 4-axle weight limits

• Compatible with rail gauge

• Limited to 12te maximum waste package (i.e. Volume of 3.7m3)

Note: A generic ‘con’ of all the RTC Options which isn’t fully captured in Ref. 8 is the requirement to move to the 8-axle rail wagon.

Option #1

Pros Cons


• Lid jamming will not occur at < 15° from horizontal

• Cannot fit canopy

• Longer seal, leak rates will be higher, possibly leading to higher spec / more complex testing such as mass spectrometry

TD/ETS/R/10/206 Rev 0 110

Option #3

Pros Cons

• Smaller seal length than either the SWTC or Option 1

• Handling underground may be an issue, but similar requirements in principal to the DCTC

• Need to rotate from horizontal to vertical for loading could prove an issue

• Not all waste producing sites could handle this large mass RTC

• GDF shaft technology currently specified at 80te limit (also similar limit for a drift access

Option #4A

Pros Cons

• Can potentially handle ‘longer’ items of waste than current SWTC

• Issue of ‘reduced waste package storage’ in GDF as recorded in Ref. 8 isn’t an actual issue

• Relatively small increase in carrying capacity over the SWTC

Option #4B

Pros Cons

• Slight increase of long item carrying capability over #4A

• Simplified waste package lifting (potentially 3-point lifts)

• -

Option #5

Pros Cons

• Substantial increase in ability to carry ‘long’ items of waste i.e. reduced size

• GDF shaft technology currently specified at 80te limit (also similar

TD/ETS/R/10/206 Rev 0 111

reduction

• Significant reduction in overall number of transports

• Reduced operating period in GDF

limit for a drift access

• Very long containment seal (see Option #1 comments)

• Lid could bow more in the fire accident than the SWTC

• Regulatory performance doubts (which could potentially be improved if Option 9 lid retention methods are incorporated)

Option #9A, B and C

Pros Cons

• All can carry 5 x 500 litre drums

• #9C – ‘proven’ containment boundary methodology (RSTC and AGR flasks)

• Trunnions may act as punches

• #9C is very similar to the RSTC, which was rejected by waste producer sites as too complicated to operate

Option #10

Pros Cons

• More flexible design • More handling i.e. lead liners

Following lunch, the meeting discussed the scoring of each Option against a number of parameters. These parameters where modified following discussions during the meeting and the final five used are identified below, with brief descriptions;

Operations – RTC handling (lifting, tilting – if required), lidding / de-lidding operations, seal testing, lid bolting etc.

Working Capacity – based upon the maximum volume of waste package that could potentially be transported.

Regulatory Performance – As judged by the engineers present, the critical regulatory test was seen as impact performance and judgements where focused on this, but also taking into consideration fire accident performance (Thermal stress issues) and the seal leakage issue raised earlier in the meeting.

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Manufacturability – INS had identified in TD/ETS/R/09/202 that all the Options could be manufactured. Some designs are obviously more of a challenge than others and so are scored on this basis.

GDF Operations – was added during the meeting, as it was evident that some of the options would challenge the current specifications of equipment and the available space in the proposed GDF.

Each parameter was reviewed in turn for all of the options (and sub-options) to ensure scoring was on the basis of relative merits, thus providing bench-marking of options against one another.

The results were captured in an excel spreadsheet by INS and this study is recorded on the following page.

Following the scoring exercise, the meeting then decided how the five parameters should be weighted, which then identified the two options most suitable for further development.

The parameter weighting methodology and a discussion on sensitivity analysis is also discussed, following a record of how each Option scored against the five parameters.

Scoring was done as a team exercise by first agreeing upon the best and worst performing options and then scoring those remaining on a relative scale between these limits.

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RTC Size Review Workshop - Scoring Category Weighting

1st run

2nd run

Operations 20 10 Volume 25 25 Regulatory Performance 30 40 Manufacturability 5 5 GDF Operations 20 20 100 100 Scoring: Rate each option with points from 1 to 10, high = better

Scoring Category

Option 1 -

Max

Option 3 -

Flask

Option 4A -

Cylinder

Option 4B -

Polygon

Option 5 -

Stretched

Option 9A - Lid

Retention

Option 9B - Lid

Retention

Option 9C - Lid

Retention Option 10

- Lined

Operations 9 4 10 9 5 1 9 6 9 Volume 5 8 1 3 10 5 5 5 6 Regulatory Performance 8 10 9 8 1 2 2 4 4 Manufacturability 9 9 10 4 1 5 9 8 6 GDF Operations 10 1 10 10 2 6 10 9 10

Total 41 32 40 34 19 19 35 32 35 Weighted Performance (1st run) 780 705 735 705 385 360 540 565 630 Weighted Performance (2nd run) 790 645 795 765 425 350 610 585 680

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Following are the general comments made during the scoring process as the RTC Options where assessed against the 5 parameters. The scores from the Excel sheet are also provided.

All scores are out of 10; 10 = best perceived performance, 1 = worst

Parameter – ‘Operations’

Option Score Comments

1 9 Same operations method as SWTC in principal

3 4 Requires large area to work in, a lot of ancillary kit

4A 10 Similar to SWTC, but possibly easier due to circular form

4B 9 Same operations method as SWTC in principal

5 5 Generally same as SWTC, but much heavier body, lid, packages

9A 1 Very difficult to handle, secure and leak test the lid

9B 9 Should be same as SWTC in principal

9C 6 Same as A2 flasks, but more lid handling / bolting

10 9 Should be same as SWTC in principal (noting fitting / removing liners would be an ‘off-line’ operation

Parameter – ‘Working Capacity’


1 5 4.42m3 waste package possible


4A 1 Smallest capacity – 3.75m3 waste package possible

4B 3 4.15m3 waste package possible

5 10 Largest capacity – 8.5m3 waste package possible

9A 5 4.5m3 waste package possible

9B 5 4.95m3 waste package possible

9C 5 4.8m3 waste package possible


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Parameter – ‘Regulatory Performance’


1 8 Similar to SWTC which is proven, although greater mass and volume / longer seals

3 10 As irradiated fuel flask design i.e. bespoke separate shock absorbing systems so judged best for impact and protection of seals during regulatory fire

4A 9 Slightly better than Option 1 due to geometry

4B 8 Similar to Option 1, but probably reduced from Option 4A

5 1 No confidence could meet impact requirements, long containment seal

9A 2 May not perform well in the punch test or lid retention during 9m drop

9B 2 No external shock absorbers, judged would have poor impact performance

9C 4 Better than other sub-options of 9, similar to RSTC

10 4 Retention of liner during a lid down impact seen as difficult to achieve

Parameter – ‘Manufacturability’


1 9 Proven technology (SWTC)

3 9 Proven technology (Numerous Irradiated Fuel Flasks)

4A 10 As Option 1, but easier to cast or forge body also circular form easies machining

4B 4 Increased casting / forging issues, machining more difficult

5 1 Very limited supplier base, (possibly only 3 world-wide) most machining, greatest cost

9A 5 Difficult to machine, install and maintain lid mechanisms

9B 9 As Option 1

9C 8 Similar to Option 1 with additional machining

10 6 Similar to Option 1, but need to also supply liner which uses lead

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Parameter – ‘GDF Operations’


1 10 Similar to SWTC

3 1 High mass, large volume to work in required

4A 10 Same if not better than Option 1

4B 10 Same if not better than Option 1

5 2 Similar to Option 3 regards mass, but requires less working volume i.e. no need to rotate the RTC into the vertical

9A 6 Awkward lid opening

9B 10 Similar to Option 1

9C 9 Similar to Option 1, but 2 lids require handling

10 10 Similar to Option 1

The meeting now discussed how the parameters should be weighted and initially, the following values were agreed upon, assuming all as a percentage;

Weightings 1

Operations… 20%

Volume… 25%

Regulatory Performance… 30%

Manufacturability… 5%

GDF Operations… 20%

By using these values and multiplying by the relevant scores, Option 1 and Option 4A had the highest points.

However, some of the attendees were not entirely satisfied with the weightings, as it was thought more importance should be being placed on regulatory performance. A second set of weightings was therefore compiled, as overleaf;

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Weightings 2

Operations… 10%

Volume… 25%

Regulatory Performance… 40%

Manufacturability… 5%

GDF Operations… 20%

Inputting these values into the spreadsheet indicated the same result i.e. Options 1 and 4A still had the highest scores. This simple sensitivity analysis therefore provides a further degree of confidence in the meetings findings.

Toward the end of the meeting, it was commented that Option 5 has some potential advantages and it was generally agreed that with some modifications e.g. partitioning of the RTC body, possibly incorporation of ‘Option 9’ type lid attachment improvements, this option could be worthy of further study. This work is outside of the current work-scope of INS (i.e. to deliver the 2 selected options), but some scoping work may be included if time allows.

Summary of Meeting

The six RTC options developed by INS and recorded in TD/ETS/R/09/202 were reviewed in the meetings against five critical parameters. Following option scoring, the parameters were weighted and it was found that Options 1 and 4A had the highest scores.

A second set of parameter weightings had no effect on the two highest scoring options. Option 1 and 4A will therefore be developed by INS. This work will include the following;

• Assess and record whether two off of each selected options (without increasing their widths as indicated in Ref. 8) could be transported on the 8-axle rail wagon. Assess axle loadings.

• Reduce the 8-axle rail-wagon bed length, thus reduce over-throw and potentially increase the RTC option widths (for 1 RTC per wagon transports)

• Develop the associated waste packages for each selected option

• Develop stillages for waste packages as required for each selected option

• Investigate containment seal lengths and compare with SWTC performance

• Investigate how impact performance could be improved for the 2 selected options.

Review of the Standard Waste Transport Container Size and ...

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