Transcript The SADRWMS tool

The SAFRAN tool
Safety Assessment in Predisposal
Waste Management
IAEA 21-25 March 2011
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.
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
Overview of SAFRAN Tool
projects and databases.
4
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.
AUGUST 2010 – RELEASE OF VERSION 1.0
• Testing by Studsvik AB
• Preparation of User Guide an Tutorials
• Improvements in 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
Safety Assessment
Regulatory
Framework
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
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
SAFREQ
Report
System description
Site features, waste
producers, waste streams
Safety Assessment
Regulatory
Framework
Normal operation,
accidents
SAFCALC
DATABASE
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
SAFREQ
Report
System description
Site features, waste
producers, waste streams
Safety Assessment
Regulatory
Framework
Normal operation,
accidents
SAFCALC
DATABASE
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
PIE Type
PIE 1
Scenario 1
Scenario n
Impact 1
Impact n
Endpoint 1
Endpoint n
Ass Case 1
Ass Case n
PIE 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
Very High
Probability
during lifetime
> 95 %
Annual probability
1/y
> 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
SAFREQ
Report
System description
Site features, waste
producers, waste streams
Safety Assessment
Regulatory
Framework
Normal operation,
accidents
SAFCALC
DATABASE
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
SAFREQ
Report
System description
Site features, waste
producers, waste streams
Safety Assessment
Regulatory
Framework
Normal operation,
accidents
SAFCALC
DATABASE
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