SAFRAN

Version 2 will be released in

August 2013

Rodolfo Avila, Facilia AB

Outline

• Overview of SAFRAN

• Enhancements to support safety assessments

for the management of DSRSs and the Borehole

Disposal Concept (BDC)

• Generic Operational Safety Assessment

(GOSA) for the management of DSRSs

What is SAFRAN

• SAFRAN is a software package for safety

assessment in pre-disposal waste

management.

• It implements the methodology developed

within the IAEA project SADRWMS (2005-

2010)

SADRWMS

methodology

Assessment Context

Description of Facility or Activity and the Waste

Identification of Hazards

Development and Justification of Scenarios

Identification of Scenarios

Formulation of Models and Identification of Data Needs

Evaluation of Results

Analysis of Safety Measures

Analysis of Engineering

Performance of Calculations

Comparison with Assessment Criteria

Engineering design, Safety measures,

Other relevant information (management systems, operational

experience, site data …)

Models and computer codes; Generic / site specific data

Purpose, Regulations, Standards …

PIE lists, Expert judgements

Screening of Hazards

Review and

modify

Adequate? Accept Independent verification

Yes Yes No

No

Adequate?

Provides detailed

guidelines for safety

assessment.

Based on the IAEA

safety guide DS284

(GSG-3): The Safety

Case and Safety

Assessment for

Predisposal Management

of Radioactive Waste

The SADRWMS methodology

• Provides detailed advice for each step of the

Safety Assessment

• Describes the different types of

assessments that might be required

• Provides methods for Hazard identification

and screening

• Provides methods for performing qualitative

and quantitative assessments for different

scenarios

SAFRAN components

System description Site features, waste

producers, waste streams

Regulatory

Framework

Safety Assessment Normal Operation,

Accidents

SAFREQ

SAFCALC DATABASE

Report

Report

System Description

For each configuration

• Site

• Facilities

– Rooms

» Areas (Storage or Processing)

Safety elements

• Waste Management Activities

– Processes

– Check for clearance

• Waste Producers

– Primary Waste Components

» Waste Streams

Safety elements

• Site selection

• Safety functions

• Limits and conditions

• Mantainance requirements

• Operational procedures

• Emergency procedures

• Management systems

Can be linked to physical elements and

assessments

Waste management activities

• Description

• Output(s) from activities

• Reduction factors

• One and only one WMA can be assigned

to an area

A process is a sequence of WMAs which can

be used in defition of Waste Streams (WS)

Waste Streams

• Waste streams represent the fate of waste

components through different steps of

processing, storing and clearing of wastes

• Accounting for changes in waste properties

by waste management activities at each

step.

Enhancements for application to DSRS

• Different forms for Sources, Solid and Liquid waste.

• Table with inventory of sources

• Library of sources

• Individual sources are traced in a project

• Possibility to calculate dose rates for WCs

• A library of safety elements of relevance for the safe

management of sources

• A library of pre-disposal waste management activities

• A library of typical processes for management of sources

• Incorporation of SIMBOD (Source Inventory Management

for Borehole Disposal) is an inventory tracking database

tool.

SAFRAN components

System description Site features, waste

producers, waste streams

Regulatory

Framework

Safety Assessment Normal operation,

accidents

SAFREQ

SAFCALC DATABASE

Report

Report

Assessment types

• For normal operation and accidents.

• Doses to workers and members of the

public.

• Radiological impacts indoors and outdoors.

Graded approach to the assessments

Impacts

Screening or

Hazards

Dose

Assessment

Calculations of Hazard

Quotients (HQ) for

standardized conservative

exposure situations

calculations for specified

endpoints and expecific

exposure conditions

Assessments for accidents

Impact 1

PIE Type

PIE 1 PIE n

Scenario 1 Scenario n

Impact n

Endpoint 1 Endpoint n

Ass Case 1

Ass Case n

Scenario m

Impact m

Screening of hazards

Example of Probability-Consequence plots

HQ/Prob Very

Low

Low Medium High Very

High

<0.1 SC3

0.1- 1 SC4

1-10 SC2

10-100

>100 SC1

Enhancements for application to DSRS

• Update of the PIE database

• Library of typical scenarios

• Library of generic safety assessments

• Wizard for performing the assessments step

by step – eLearning module

SAFRAN components

System description Site features, waste

producers, waste streams

Regulatory

Framework

Safety Assessment Normal operation,

accidents

SAFREQ

SAFCALC DATABASE

Report

Report

Models available in SAFCALC

• IAEA SR-19 models: screening models for

routine releases to the atmosphere, lakes,

rivers, estuarines and coastal areas.

• Model for accidental releases to the

atmosphere.

• Model for accidental releases inside a room.

• Simple dosimetry models: point source, disc,

cylinder, cube (with and without shielding)

SAFRAN components

System description Site features, waste

producers, waste streams

Regulatory

Framework

Safety Assessment Normal operation,

accidents

SAFREQ

SAFCALC DATABASE

Report

Report

Database

• Radionuclide half lives.

• Clearance levels.

• Gamma constants – dose rates at 1 m from a point source.

• Screening dose rates for Normal and accidental situations.

• Screening release rates for Normal operation.

• Screening releases for accidental situations.

• Release Fractions.

• Dispersion factors.

• Dose Conversion Factors for Normal and accidental

situations.

Additions for BOSS

• Models and calculation methods used in Generic

Operational Safety Assessment (GOSA).

• Parameter values required for GOSA.

SAFRAN components

System description Site features, waste

producers, waste streams

Regulatory

Framework

Safety Assessment Normal operation,

accidents

SAFREQ

SAFCALC DATABASE

Report

Report

SPECIALIZED LIBRARIES FOR BOSS

SAFREQ

• Tool for assistance in developing the safety

case by assessing compliance with Safety

Requirements and Safety Guidelines.

GENERIC OPERATIONAL SAFETY

ASSESSMENT (GOSA)

Assessment Context

• The assessment context of the GOSA

should be consistent with the generic safety

assessment (GSA) for borehole disposal

(IAEA Safety Series Report: Generic Post-

Closure Safety Assessment for Borehole

Disposal of Disused Sealed Sources)

Purpose

• The purpose of the GOSA is to demonstrate that

the proposed pre-disposal waste management

activities are done in a safe manner, as required

by the regulatory framework. The safety of

operators (workers) and members of the public will

be assessed, both for normal operations and for

potential accidental situations.

Scope

• The starting point for the GOSA is that the Disused Sealed

Sources (DSSs) have arrived at the site.

• Activities of the original producer [e.g. hospital] and

transport to site are beyond the scope of the current

project).

• Different disposal options (storage for decay, disposal in a

near-surface or deep facility, BDC) and management

options (long-term storage) will be considered.

Inventory to be considered

• The inventory (Bq) and number of sources to be assessed

in the GOSA need to be representative of what is found in

practice in different countries.

• An initial proposal is to consider two cases: a country

(Ghana being an example) with a low to medium inventory

of relatively low level activity sources that do not require the

use of hot cells, and a country (South Africa being an

example) with a medium to large inventory which includes

high activity sources that will require the use of hot cells. • Different initial states of the sources should be considered,

including sources in the original devices, in a transport

package, in the working container, and conditioned in

cement.

Regulatory Framework

• IAEA Safety Standards will be used as the basis

for the regulatory framework.

• This will include normal operation and accidental

situations, taking into account dose constraints as

well as dose limits.

• Doses to the eye, extremities, etc., in addition to

whole body doses, will be calculated.

Inventory of sources

Sources for Disposal

Sources for Decay Store

Classification of sources

Other Disposal Options

Sources for BDC

Screening on total

inventory

Several Boreholes might be required

Number of capsules required for one borehole

Allocation of Sources to capsules

Use SAFCALC to obtain operational activity limits for capsules

WMA, etc

IAEA databases, SIMBOD, etc

Temporary Storage at Site

Prepare for Introduction into Cell

Remove Source and Characterise

Lift original Source Shield into Cell

Close Cell

Encapsulation and Testing

Condition into Disposal Container

Lower into Borehole

Borehole Backfilling

Transfer Container to Transfer Cask

Lower into Borehole

Borehole Backfilling

Operational activities Duration

(Minutes)

1) Prepare for Introduction into hot cell 15

2) Lift Original Source Shield into the hot cell 5

3) Close the hot cell 20

4) Remove the source 60

5) Characterise the source 20

6) Encapsulation and test of the capsule 20

7) Place capsule in disposal container and NDT 20

8) Transfer disposal container to the transfer cask 10

9) Disengage and prepare the transport cask for

transport

15

10) Emplacement of the disposal container in borehole 15

11) Backfilling of the borehole 15

Typical activities for operational phase of the BDC

Examples of accidental scenarios (hot cell)

• The situation where the operation team is unaware that the source has an

activity greater than the value for what the facility was designed for and the

team proceeds with standard operations.

• Error during the determination of the density of the shielding material (sand) in

the hot cell and the operation proceeds with a sand density below design

requirements.

• Situation with the ZnBr2 window density below design requirements being used

by the operation team.

• Source is dropped after being removed from the original source shield.

• The source is found to be leaking when removed from the original source shield

inside the hot cell. (Could have been damaged during removal).

• The manipulators malfunction whilst the source is inside the hot cell.

• The biological shield is damaged while bringing in the original source shield.

• Power outage in the hot cell.

• Lights are not operational in the hot cell.