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Safety factors for periodic safety review for research

reactors

Group A: SF1 – SF4

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Starting points• SSG-25: Periodic Safety Review for NPPs

– SF1: Plant design;– SF2: Actual condition of SSCs important to safety;– SF3: Equipment qualification;– SF4: Ageing.

• NS-R-4: Safety of Research Reactors• SSG-37: Instrumentation and Control Systems

and Software Important to Safety for Research Reactors

• SSG-20: Safety Assessment for Research Reactors and Preparation of the Safety Analysis Report.

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To be taken into account• For small, low risk facilities (such as critical assemblies or

reactors with low power levels), these requirements are much less stringent. However, as the safety analysis report is often the only comprehensive document produced, every topic discussed in the Appendix to this Safety Guide should be considered.

• Although the extent of information on each topic would be limited, the scope of some topics (e.g. the protection of operating personnel against overexposure in critical assembly facilities) may be much larger for small, low power facilities.

[Para 3.16 of SSG-20]

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SF1• The objective of the review of reactor design is to

determine the adequacy of the design of the research reactor including its experimental infrastructures and its documentation by assessment against the current licensing basis and national and international standards, requirements and practices.

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SF1• Review of the list of SSCs important to safety for

completeness and adequacy.• Review to verify that design and other characteristics are

appropriate to meet the requirements for reactor safety and performance for all operational conditions and the applicable period of operation, including:– The prevention and mitigation of events (faults and hazards)

that could jeopardize safety;– The application of defence in depth and engineered barriers

for preventing the dispersion of radioactive material (integrity of fuel, cooling circuit, experimental loops and containment building);

– Safety requirements (for example, on the dependability, robustness and capability of SSCs important to safety);

– Design codes and standards.

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SF1• Identification of differences between standards met by the

research reactor’s design (for example, the standards and criteria in force when it was built) and modern nuclear safety and design standards.

• Review of the adequacy of the design basis documentation.

• Review for compliance with the research reactor design specifications, including experimental facilities.

• Review of adequacy of core management in the facility.• Review of the safety analysis report or licensing basis

documents following modifications to the research reactor and its experimental facilities and in light of their cumulative effects and updates to the site characterization.

• Review of structural materials used in the experimental facilities, taking into account their ageing and activation.

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SF1• Review of plant SSCs important to safety to ensure that

they have appropriate design characteristics and are arranged and segregated in such a way as to meet modern requirements for research reactor safety and performance, including the prevention and mitigation of events that could jeopardize safety.

• Review of the strategy for the spent fuel storage and conduct of an engineering assessment of the condition of the storage facilities, the records management and the inspection regimes being used.– For RRs: smaller volumes of spent fuel; criticality issues; specific

corrosion issues.

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SF2• The objective of the review of this safety factor is to

determine the actual condition of SSCs important to safety and so to consider whether they are capable and adequate to meet design requirements, at least until the next PSR.

• In addition, the review should verify that the condition of SSCs important to safety is properly documented, as well as reviewing the ongoing maintenance, surveillance and in-service inspection programmes, as applicable.– Important to emphasize the need for proper documentation, even

in very small facilities.

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SF2• The review of the actual condition of the SSCs important

to the safety of the research reactor should include examination of the following aspects for each SSC:– Existing or anticipated ageing processes;– Operational limits and conditions, including, provisions for

commissioning of the reactor and experimental facilities.– Current state of the SSC with regard to its obsolescence;– Implications of changes to design requirements and standards on

the actual condition of the SSC since the research reactor was designed or since the last PSR (for example, changes to standards on material properties);

– Influence of experimental devices on reactor safety.– Plant programmes that support ongoing confidence in the

condition of the SSC; [Maintenance records; records of failures]– Significant findings from tests of the functional capability of the

SSC;– Results of inspections and/or walkdowns of the SSC;

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SF2• Examination of the following aspects (cont.):

– Maintenance and validity of records;– Evaluation of the operating history of the SSC;– Dependence on obsolescent equipment for which no direct

substitute is available;– Dependence on essential services and/or supplies external to the

research reactor; [Mostly for larger facilities]– The condition and operation of spent fuel storage facilities and

their effect on the spent fuel storage strategy for the facility;[same comments as before on specific issues for RR fuel]

– Verification of the actual state of the SSC against the design basis.

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SF3• The objective of the review of equipment qualification is to

determine whether research reactor, including its experimental facilities, equipment important to safety has been properly qualified (including for environmental conditions) and whether this qualification is being maintained through an adequate programme of maintenance, inspection and testing that provides confidence in the delivery of safety functions until at least the next PSR.

• SSG-37: Instrumentation and control systems and components important to safety should be qualified for their intended functions. The qualification should provide a degree of confidence commensurate with the safety classification of the system or component.The basis for qualification should be documented.

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SF3

Safety classification of nuclear power plant equipment.Do we need safety grade class 1E in (all) RRs?

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SF3

Commercial and nuclear-grade pressure transmitters from Rosemount (Hashemian, Maintenance of Process Instru-mentation in NPPs, Springer, 2006).

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SF3• The review of equipment qualification should consider:

– Whether installed equipment meets the qualification requirements;– The adequacy of the records of equipment qualification;– Procedures for updating and maintaining qualification throughout

the service life of the equipment;– Procedures for ensuring that modifications and additions to SSCs

important to safety do not compromise their qualification;– Surveillance programmes and feedback procedures used to

ensure that ageing degradation of qualified equipment remains insignificant;

– Monitoring of actual environmental conditions and identification of ‘hot spots’ of high activity or temperature;

– Protection of qualified equipment from adverse environmental conditions.

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SF4• The objective of the review of ageing is to determine

whether ageing aspects affecting SSCs important to safety are being effectively managed and whether an effective ageing management programme is in place so that all required safety functions will be delivered for the design lifetime of the research reactor and, if it is proposed, for long term operation.

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SF4• The review should evaluate the following aspects:

– Ageing management methodology;– The operating organization’s understanding of dominant ageing

mechanisms and phenomena, including knowledge of actual safety margins;

– Availability of data for assessing ageing degradation, including baseline data and operating and maintenance histories;

– Acceptance criteria and required safety margins for SSCs important to safety;

– Operating guidelines aimed at controlling and/or moderating the rate of ageing degradation;

– Methods for monitoring ageing and for mitigation of ageing effects;– Awareness of the physical condition of SSCs important to safety and

any features that could limit service life;– Understanding and control of ageing of all materials (including

consumables) and SSCs that could impair their safety functions;– Obsolescence of technology used in the research reactor, including

its experimental facilities.

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Tasks 3 and 4

Group A

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Task 3: Introduction• The existence of experimental devices, tests &

reactor physics experiments is one of the most significant differences between NPPs and Research Reactors.

• This justifies a new Safety Factor taking into account the utilization and safety of experiments.

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Utilization and Safety of Experiments1. Inputs1a. Standards & requirementsTo point current national & international standards on reactor

utilization and safety of experiments

1b. Reactor specific documents1. Reactor utilization (experimental devices, tests and

reactor physics experiments);2. Description of experimental devices design;3. Safety analysis of the reactor experimental devices (e.g.

influence of experiments & experimental devices such as flooding or voiding);

4. Quality assurance program for authorized experiments;

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Utilization and Safety of Experiments1b. Reactor specific documents (cont.)5. Operational & maintenance records for the experimental devices;6. OLCs for the reactor operation and for the experiments;7. Records of modifications for experimental devices;8. Experimental devices safety-related data and trends;9. Reports of walkdowns;10.List of failures of experimental devices & causes of failure;11.Procedures of utilization of experimental devices;12. Information about the integrity and functional capability of experimental devices including material case histories;13. Radiation doses to persons in relation to the experiment;14. Record on radioactivity releases in relation to the performed experiment.

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Utilization and Safety of Experiments2. Processes to be reviewed•Influence of experimental devices on the reactor safety;•Influence of the reactor utilization on reactor safety;•Assessment of special OLCs that may be required for an experiment;•Ageing management of experimental devices;•Verification of experimental devices personnel.

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Utilization and Safety of Experiments3. Methodology1. Experimental devices should be classified, designed, manufactured and qualified according to their importance to safety. At a minimum the PSR should verify that the standards and requirements in use of experimental devices remain valid. Review should include:a) Changes in the experimental devices classification resulting from design modifications;b) Changes in equipment required to fulfil safety functions;c) Quality management provisions ensuring that an effective qualification program is in place.

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Utilization and Safety of Experiments3. Methodology (cont.)2. The review of experimental devices qualification should determine:a) Whether adequate assurance of the required experimental device performance was initially provided;b) Whether current experimental devices qualification specifications and procedures are still valid (e.g. regarding service life);c) Whether experimental devices performance has been preserved by on-going application of measures such as scheduled maintenance, condition monitoring, testing and calibration and whether such programs have been properly documented.

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Utilization and Safety of Experiments3. Methodology (cont.)3. Consideration should be given to the effects of any changes in experimental devices operation (for example, the use of a new design of device) on safety performance.In particular, the review should evaluate the continuing relevance of the current indicators and other safety performance methods in the context of current and future experimental device operations, and ensure that only relevant data and records are used.

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Utilization and Safety of Experiments3. Methodology (cont.)4. The review should evaluate the adequacy of the experimental devices safety performance methodologies and processes with regard to:a) Root cause analysis of incidents and feedback of results;b) The qualification of personnel carrying out experiments;c) The quality of procedures;d) Records of radiation doses and radioactive releases due to operation of experiments.

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Utilization and Safety of Experiments4. OutputsThe review of utilization and safety of experiments may lead to findings in some of the following areas:•Need to update safety analysis for experiments;•Elaboration of new operational procedures for experiments;•Need for additional training for personnel operating experiments;•Need to update quality assurance programs for experiments;•Need to update the utilization program.

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Utilization and Safety of Experiments SF

1 S 2

SF 3

SF 4

SF 5

SF 6

SF 7

SF 8

SF 9

SF 10

SF 11

SF 12

SF 13

SF 14

SF 15

SF 1 X

SF 2 X

SF 3

SF 4

SF 5 X

SF 6

SF 7 X

SF 8 X

SF 9 X

SF 10 X

SF 11 X

SF 12 X

SF 13 X

SF 14 X

SF 15 X X X X X X X X X X X X X

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Task 4Improvements since June 2014 to application of CoC:•Radiological zoning•Emergency ventilation system•Improvements in:

– Safety analysis;– Radiological protection system;– Instrumentation & control system;– Emergency cooling system;– Inspection of reactor vessel & primary cooling system.

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Task 4Main difficulties to application of CoC:•Lack of sufficient resources, human and financial.

Opportunities for regional cooperation on CoC:•Workshops.•Regional group of research reactor regulators.

Forms and scope of IAEA assistance:•INSARR missions;•Expert missions;•Technical projects;•Safety standards, safety guides and tecdocs.