SAFRAN

Workshop on the Application of the IAEA Methodology and Safety Assessment Framework (SAFRAN) Tool for the Safety Case (SC) and Safety Assessment (SA) for Predisposal Management of Disused Sealed Radioactive Sources (DSRS) Athens, GREECE 23-27 June 2014

SAFRAN

A software package for assessing radiological safety of pre-disposal waste management activities

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.

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.

Overview of SAFRAN Tool 4

History of the development (1)

• The tool development started in April 2005 In the frame of the IAEA project: SADRWMS –

S

afety

A

ssessment

D R

adioactive

M

anagement

S

olutions riving • From April 2007 it was introduced in another IAEA project: DeSa –

S

afety

A

ssessment in Decommissioning • From 2008 – Sponsoring from SSM (Sweden), NDA (UK) and IRSN (France)

History of the development (2)

• • • From April 2008 - development of a new User Interface and new Calculation Tool based on Ecolego.

Development of website for downloading the tool.

Development of first version of User Guide in Wiki language.

• • •

AUGUST 2010 – RELEASE OF VERSION 1.0

Testing by Studsvik AB Preparation of User Guide and Tutorials Some improvements in the Safety Assessment Module

Test Cases

• • • • • • Development of specifications: Treatment plant in Vinca, IAEA training courses: Slovenia, Croatia, Moscow, Belarus, Chile and Cuba, Development of specifications for decommissioning: Decommissioning of a nuclear laboratory in the US.

Waste Treatment Plant and Storage facility of the Leningrad Nuclear Power Plant, Treatment Plant in Studsvik – 2 iterations (Sweden), National waste treatment and storage facility in Thailand.

SAFRAN components

SAFREQ Report System description Site features, waste producers, waste streams Regulatory Framework Safety Assessment Normal Operation, Accidents SAFCALC DATABASE Report

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

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

Waste management activities

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

Reduction factors

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

Output

Combustible Non combustible

Volume

5 % 95 %

Massa

5 % 95 %

Activity

5 % 95 %

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

Processes

• 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 • Consider changes of waste properties in these steps.

SAFRAN components

SAFREQ Report System description Site features, waste producers, waste streams Regulatory Framework Safety Assessment Normal operation, accidents SAFCALC DATABASE Report

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

SAFRAN components

SAFREQ Report System description Site features, waste producers, waste streams Regulatory Framework Safety Assessment Normal operation, accidents SAFCALC DATABASE Report

Assessment types

• • For normal operation and accidents.

Doses to workers and members of the public.

• Radiological impacts indoors and outdoors.

Assessment context

• • • • Link to one or more Regulatory Frameworks Purpose – select from a list or add own Scope – Define which facilites, rooms and areas will be included in the SA and at what level the assessment is carried out Approach • • • PIEs will be defined or only PIE types will be used.

Include or not a step for Screening of Hazards.

Compliance with Safety Requirements will be assessed or not?

Graded approach to the assessments

Impacts Screening or Hazards Dose Assessment

Optional step

calculations for standardized conservative exposure situations calculations for specified endpoints and expecific exposure conditions

Safety Assessment for Normal Operation

• • Endpoints definition – several endpoints that can be optionally linked to one or more regulatory criteria • • Indoors and Outdoors Dose (Sv/y) or Other Scenarios • • • • • Relevant or not relevant Bounded or not (if bounding scenarios are defined) Quantitative or qualitative Indoors or outdoors Radiological consequences • Indoors: Direct external exposure and exposure by inhalation or Other • Outdoors: Releases to air, liquid discharges or Other

Normal operation scenarios

• Impacts are classified by their location and type: • Inside the facility (workers exposure) • • Direct external exposure and exposure via inhalation, Other; • Outside the facility (public exposure): • • • Releases to air, Liquid discharges, Other.

24

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) 25

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.

27

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).

28

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: 29

30

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

Assessments for accidents

PIE Type PIE

1

PIE

n

Scenario

1

Impact

1

Impact

n

Endpoint

1

Ass Case

1

Ass Case

n

Endpoint

n

Scenario

n

Scenario

m

Impact

m

Screening of hazards

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 Qualitative Category

Very High High Medium Low Very Low

Probability during lifetime

> 95 % 75-95 % 5-75 % 0,1-5 % < 0,1 %

Annual probability 1/y

> 3,0E-02 1,4E-02 - 3,0E-02 5,0E-04 - 1,4E-02 1,0E-05 - 5,0E-04 < 1,0E-05

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

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.

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

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 (m 3 ) 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.

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.

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.

Example of Probability-Consequence plots HQ/Prob Very Low

<0.1

0.1- 1 1-10 10-100 >100 SC1

Low Medium High Very High

SC3 SC4 SC2

SAFRAN components

SAFREQ Report System description Site features, waste producers, waste streams Regulatory Framework Safety Assessment Normal operation, accidents SAFCALC DATABASE 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)

Uncertainty analysis

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

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

SAFRAN components

SAFREQ Report System description Site features, waste producers, waste streams Regulatory Framework Safety Assessment Normal operation, accidents SAFCALC DATABASE 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.

SAFRAN components

SAFREQ Report System description Site features, waste producers, waste streams Regulatory Framework Safety Assessment Normal operation, accidents SAFCALC DATABASE Report

SAFRAN website

• • • • • • • www.safran.facilia.se

Free download of the software and documentation Online User Guide Tutorials SAFRAN projects – TNIT test case GOSA Discussion Forum