The SAFRAN tool

Safety Assessment in Predisposal

Waste Management

Purpose of the tool

Implementation of methodologies for SA in pre-disposal

waste management developed in the frame of the

SADRWMS project. The tool should be helpful in:

• Describing predisposal radioactive waste management and

decommissioning activities in a structured 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

Areas of application

The tool is applicable to pre-disposal waste management activities:

• retrieval, treatment and storage of existing wastes;

• treatment and storage of decommissioning wastes;

• treatment and storage of institutional wastes (e.g. sources);

• treatment of liquid waste;

• clearance of waste;

• discharges.

Overview of SAFRAN Tool 5

Benefits of SAFRAN

• Provides methodologies recommended by the IAEA and tools that have been conciliated at international level.

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

• Facilitates regulatory review by providing a transparent representation of all SA components.

• Several experts can work more effectively in the same Safety Case. The regulator can use the SAFRAN projects in independent safety assessments

• SAFRAN can be used for creating generic safety assessments

• Possibility to exchange experience through sharing projects and databases.

History of the development (1)

• The tool development started in April 2005

In the frame of the IAEA project: SADRWMS – Safety Assessment Driving Radioactive Management Solutions

• From April 2007 it was introduced in another IAEA project: DeSa – Safety Assessment 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.

• Translation of the interface to Russian language.

• Testing by Studsvik AB

• User Guide and Tutorials

• Improvements in Safety Assessment Module

• AUGUST 2013 – RELEASE OF VERSION 2.0

http://facilia4.space2u.com/safran2/safran/show/HomePage

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 (Sweden),

• National waste treatment and storage facility in Thailand.

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)

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 Volume Massa Activity

Combustible 5 % 5 % 5 %

Non combustible 95 % 95 % 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

• The definition of waste streams allows

representing the fate of waste components

through different steps of processing,

storing and clearing wastes and allows to

consider changes of waste properties in

these steps.

SAFRAN components

System description Site features, waste

producers, waste streams

Regulatory

Framework

Safety Assessment Normal operation,

accidents

SAFREQ

SAFCALC DATABASE

Report

Report

Regulatory Framework

• Regulatory requirements

• Criteria Normal operation and accidents.

Workers and members of the

public

Dose in Sv/y

• Several regulatory frameworks can be

added to a project, for example IAEA and

national and all can be used in a SA

SAFRAN components

System description Site features, waste

producers, waste streams

Regulatory

Framework

Safety Assessment Normal operation,

accidents

SAFREQ

SAFCALC DATABASE

Report

Report

Safety Assessment types

• Normal operation and accidents

• Impact on workers and members of the

public

• Impact inside and outside the facilities

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 at at what level the assessment is

carried out

• Approach

– PIEs will be defined or only PIE types will be used.

– Screening of Hazards will be done or not

– Compliance with Safety Requirements will be assessed

or not?

Safety Assessment for Normal Operation

• Endpoints definition – several endpoints that can be optionally linked

to one or more criteria

– Inside and Outside

– Dose (Sv/y) or Other

• Scenarios (Impacts in normal operation)

– Relevant or not relevant

– Bounded or not (currently practically not used)

– Quantitative or qualitative

– Inside or outside

– Radiological consequences

• Inside: Direct external exposure and exposure by inhalation or

Other

• Outside: Releases to air, liquid discharges or Other

Assessment of impacts

Impacts

Screening or

Hazards

Exposure

Assessment

Optional step

calculations for

standardized conservative

exposure situations

calculations for specified

endpoints and expecific

exposure conditions

Impacts inside during normal operation external irradiation and inhalation

• Hazard quantification – External dose rates (Sv/h) and air

concentrations (Bq/m3), taken from the System Description, are used to

calculate the dose rate (Sv/h) from occupancy of the room. A Hazard

Quotient (HQ) is calculated by dividing this dose rate by a Screening

Dose Rate. The Screening Dose Rate is found in the Database – the

user can define it´s own value.

• Exposure assessment – The dose rates (Sv/h) are used for calculation

of annual doses (Sv/y) by multiplying by the exposure time. If the

same endpoint is assigned to several scenarios, then for this endpoint

SAFRAN will also calculate the sum of the doses from all scenarios.

Impacts outside during normal operation releases to air and liquid discharges

• Hazard quantification – Release rates to air (Bq/y) and liquid

discharge rates (Bq/y), taken from the System Description, are used to

calculate a Hazard Quotient (HQ) by dividing these by Screening

Release Rate or Screening Discharge Rate. The Screening Release

Rate and Screening Discharge Rate are found in the Database – the

user can define it´s own value.

• Exposure assessment – The above Release rate (Bq/y) is used for

calculation of annual doses (Sv/y) by multiplying by a Dose

Conversion Factor (DCF). Values of the DCF are found in the

Database.

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

– Inside and Outside

– Dose (Sv/y) or Other

• Scenarios and impacts

– PIEs

– Scenarios

– Impacts

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

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

Probability

during lifetime

Annual probability

1/y

Very 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

Scenario properties

• Relevant or not

• The probability may or not be the same as

the probability of the linked PIE

• Several scenarios can be linked to the same

PIE, but a scenario has 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

• Inside or outside

• Radiological consequences

– Inside: Releases to air, increased external exposure and

Other

– Outside: Releases to air, liquid discharges or Other

• If the same endpoint is assigned to several impacys 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 (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.

Impacts inside from accidents increased external irradiation

• Hazard quantification – Dose rates (Sv/h) at one meter from a point

source with an inventory (Bq) equal to the Potentially Affected

Inventory (PAI) are calculated. A Hazard Quotient (HQ) is calculated

by dividing this dose rate by a Screening Dose Rate. The Screening

Dose Rate is found in the Database – the user can define it´s own

value.

• Exposure assessment – The PAI are used to calculate external doses

using dosimetry models, available in SAFCALC for different

geometries. The values of distance from the source and exposure time,

entered by the user, are taken into account, as well as shielding effects

(optional).

Impacts inside from accidents releases to air

• Hazard quantification – The PAI is multiplied by the Release

Fraction to obtain the Release to air. A Hazard Quotient (HQ) is

calculated by dividing this Release by a Screening Release. The

Screening Release is found in the Database – the user can define it´s

own value.

• Exposure assessment – The Release (Bq) are used to estimate doses

by applying a Dispersion Factor (h/m3), which depends on the values

of distance from the source, exposure time and room volume entered

by the user. The Dispersion Factor is found in the Database – the user

can define it´s own values.

Release Fractions

• Release Fraction (RF) is the fraction of the

Potential Affected Inventory that is released

to air.

• The RF depends on the Waste form, the

radionuclide and the type of effect of the

accident.

• Values of RF are given in the Database.

• It is assumed that RF correspond to

respirable fractions.

Impacts outside from accidents releases to air

• Hazard quantification – The Release outside re obtained by

multiplying the Release inside by factor that accounts for reduction of

releases by filtration. A Hazard Quotient (HQ) is calculated by

dividing this Release by a Screening Release. The Screening Release is

found in the Database – the user can define it´s own value.

• Exposure assessment – Doses are calculated by multiplying the

Release (Bq) by a Dose Conversion Factor (Sv/Bq). The Dose

Conversion Factor values are found in the Database – the user can

define it´s own values.

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 calculations

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

System description Site features, waste

producers, waste streams

Regulatory

Framework

Safety Assessment Normal operation,

accidents

SAFREQ

SAFCALC DATABASE

Report

Report

Database

• Radionuclide halv lifes

• Clearance levels

• Gamma constants

• 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