IAEAInternational Atomic Energy Agency

Technical Meeting on the Demonstration of Operational and Long Term Safety of Predisposal Management Facilities for Radioactive Waste

IAEA Headquarters, 28 Sept.-2 Oct. 2015

Frederic Ledroit (France)

Presentation of the SAFRAN Tool

IAEAInternational Atomic Energy Agency

SAFRAN

A software package facilitating development of safety assessment of predisposal waste

management activities and facilities

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Purpose of SAFRAN

Implements methodologies developed within the SADRWMS project. It provides aid in:• Describing predisposal radioactive waste management activities in

a systematic way,

• Conducting the safety assessment with clear documentation of the methodology, assumptions, input data and models,

• Establishing a traceable and transparent record of the safety basis for decisions on proposed waste management solutions,

• Demonstrating clear consideration of and compliance with national and international safety standards and recommendations.

IAEA Overview of SAFRAN Tool 4

Benefits of SAFRAN

• Implements methodologies that have been conciliated at international level – IAEA standards.

• Facilitates performing iterations of the Safety Asessment, for example in case of upgrades of facilities, if new waste streams appear, etc.

• Several experts can work more effectively in the same safety assessment. SAFRAN facilitates exchange of experience through sharing projects and databases.

• Facilitates regulatory review by providing a transparent representation of all SA components. The regulator can use the SAFRAN projects in independent safety assessments.

• SAFRAN can be used for creating generic safety assessments.

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SAFRAN components

System descriptionSite features, waste producers,

waste streams

Regulatory Framework

Safety AssessmentNormal Operation,

Accidents

SAFREQ

SAFCALC DATABASE

Report

Report

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System Description

For each configuration• Site

• Facilities• Rooms

• Areas (Storage or Processing)

Physical elements

Safety elements• Waste Management Activities

• Processes• Check for clearance

• Waste Producers• Primary Waste Components

• Waste Streams

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Types of 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

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Waste management activities

• Description• Output(s) from activities• Reduction factors• One and only one WMA can be assigned to an area

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Reduction factors

• Define how the activity changes the waste properties: Volume, mass and activity

Sorting of waste

Output Volume Mass Activity

Combustible 5 % 5 % 5 %

Non combustible 95 % 95 % 95 %

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Check for clearance

• Possible to make comparisons of activity concentrations in the waste components against IAEA´s and user defined clearance criteria

• Clearance criteria are defined for unconditional clearance of solid materials and expressed in Bq/g

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Processes

• A process is a sequence of WMAs which can be used in defition of Waste Streams (WS)

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Waste Streams

• Waste streams represent the fate of waste components through different steps of processing, storing and clearing of wastes

• Consider changes of waste properties in these steps.

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SAFRAN components

System descriptionSite features, waste producers,

waste streams

Regulatory Framework

Safety AssessmentNormal operation,

accidents

SAFREQ

SAFCALC DATABASE

Report

Report

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Regulatory Framework

• Regulatory requirements• Criteria Doses in during normal operation (Sv/y) and

accidents (Sv).

Workers and members of the public• Several regulatory frameworks can be added to a project,

for example IAEA and national, and all can be used in the SA

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SAFRAN components

System descriptionSite features, waste producers,

waste streams

Regulatory Framework

Safety AssessmentNormal operation,

accidents

SAFREQ

SAFCALC DATABASE

Report

Report

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Assessment types

• For normal operation and accidents.• Doses to workers and members of the public.• Radiological impacts indoors and outdoors.

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Graded approach to the assessments

Impacts

Screening or Hazards

Dose Assessment

Optional step calculations for standardized conservative exposure situations

calculations for specified endpoints and specific exposure conditions

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Screening of hazards and Hazard Quotient

• Screening of hazards – implementation of the graded approach;

• For screening of hazards SAFRAN uses the concept of hazard quotient (HQ)

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HQ: External irradiation and inhalation

• SAFRAN default values:• Screening dose to worker is 0.1 mSv/y,• Annual worker exposure time is 2000 h/y (i.e. working

time is 8 h per day, 5 days per week and 50 weeks per year).

• User may set its own value for screening dose rate basing on actual conditions to be assessed.

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HQ: Releases to atmosphere

• SAFRAN default values:• Screening dose to member of the public is 0.01 mSv/y,• Release to dose calculation factors (mSv/Bq) are based

on the IAEA Safety Report Series No. 19 defined Generic Environmental Model;

• User may set its own value for screening release rate basing on actual conditions to be assessed.

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Dose assessments

• If scenario is not screened out basing on HQ• dose rate (inside facility)• release / discharge (outside facility)

then dose calculation is performed;

• Calculation continues with already identified impacting parameters (dose rate, release / discharge rate).

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Dose assessments (cont.)

• External irradiation and inhalation:• User defines actual exposure time:

• Releases to atmosphere / Liquid discharges• SAFRAN includes database of release to dose

conversion factors:

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Dose assessments (cont.)

• Releases to atmosphere / Liquid discharges• SAFRAN includes database of release to dose

conversion factors;

• SAFRAN includes SAFCALC tool where IAEA Safety Reports Series No. 19 models are implemented and can be used with user defined parameters;

• User values of DCF.

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Safety Assessment for Accidents

• PIE types• External natural• External human induced• Internal

• Endpoints definition – several endpoints that can be optionally linked to one or more criteria• Indoors and Outdoors• Dose (Sv) or Other

• Scenarios and impacts• PIEs• Scenarios• Impacts

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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

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PIE properties

• Relevant or not• Probability (per year or during facility lifetime)

• Qualitative: Very Low, Low, Medium, High, Very High• Quantitative: Probability of occuring at least once

Default scale of probabilities

QualitativeCategory

Probability during lifetime

Annual probability

1/yVery High > 95 % > 3,0E-02

High 75-95 % 1,4E-02 - 3,0E-02

Medium 5-75 % 5,0E-04 - 1,4E-02

Low 0,1-5 % 1,0E-05 - 5,0E-04

Very Low < 0,1 % < 1,0E-05

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Scenario properties

• Relevant or not• The probability may or not be the same as the probability of

the linked PIE• Several scenarios may be linked to the same PIE, but a

scenario can have only one PIE• A scenario may have several impacts and several

scenarios can be linked with the same impact

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Properties of impacts from accidents

• Relevant or not relevant

• Bounded or not (currently practically not used)

• Quantitative or qualitative

• Indoors or outdoors• Radiological consequences

• Indoors: Releases to air, increased direct external exposure and Other

• Outdoors: Releases to air, liquid discharges or Other• If the same endpoint is assigned to several impacts of

the same scenario, then for this endpoint SAFRAN will also calculate the sum of the doses from all impacts.

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Potentially Affected Inventory (PAI)

• Also known as Material At Risk • Is the radionuclide inventory or amount, in Bq, that

can be affected during an accident.

Examples• The PAI for an accident consisting of dropping a

waste package equals the total activity in the package.

• The PAI for an accident during a processing activity equals the activity involved in one instance of the activity

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Calculation of PAI

• For Storage Areas the PAI is the total activity present in the Area, i.e. the summa over all stored Waste Components.

• For Processing Areas the PAI is the Capacity of the Processing Activity (m3) multiplyied by the radionuclide concentration in the waste. For each processing activity SAFRAN calculates two PAI values, using the concentrations in the waste before and after the activity. The user has to choose between these.

• In the PAI calculation for an Area, all Waste Streams passing through this Area are considered.

• In the PAI calculation for a Room all areas in this Room are considered.

• In the PAI calculation for a Facility all Rooms in this Facility are considered.

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Release Fractions

• Release Fraction (RF) is the fraction of the Potential Affected Inventory that is released to air during the accident.

• The RF depends on the Waste Form, the Radionuclide and the Type of Effect of the accident.

• Values of RF are given in the SAFRAN Database.• It is assumed that RF correspond to respirable fractions.

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Analysis of the results

• Comparison of hazards.• Comparison of doses against regulatory criteria –

assessment of compliance.• Definition of modifications of the facilities, waste

management activities, existing and new safety elements.

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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

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SAFRAN components

System descriptionSite features, waste producers,

waste streams

Regulatory Framework

Safety AssessmentNormal operation,

accidents

SAFREQ

SAFCALC DATABASE

Report

Report

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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)

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Uncertainty analysis

• Probabilistic simulations using Monte Carlo random sampling and Latin Hypercube sampling.

• Sensititivy analyses using regressions, correlations and variance based methods.

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SAFRAN components

System descriptionSite features, waste producers,

waste streams

Regulatory Framework

Safety AssessmentNormal operation,

accidents

SAFREQ

SAFCALC DATABASE

Report

Report

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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.

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SAFRAN website

• www.safran.facilia.se• Free download of the software and documentation• Online User Guide• Tutorials• SAFRAN projects – TINT test case• Discussion Forum

IAEAInternational Atomic Energy Agency