1. SAFRAN
Upgraded to support the implementation of the Borehole Disposal Concept
Rodolfo Avila, Facilia AB

2. Outline Description of SAFRAN
Adaptation to support the implementation of the BDC.
Generic Operational Safety Assessment (GOSA)

3. 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 ( )

4. SADRWMS methodology
Provides detailed guidelines for safety assessment.
Based on the IAEA safety guide DS284: The Safety Case and Safety Assessment for Predisposal Management of Radioactive Waste

5. 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

6. Disposal Borehole Design & Construction
Diameter – 260mm
Length – variable
Casing
Diameter – 160mm
Length - variable
Disposal Container
Diameter – 115mm
Length – 250mm
Capsule
Diameter - 21/48mm
Length – 110/121mm

7. Disposal container (with concrete insert) and container lid
Disposal container (with concrete insert) and container lid. Bottom row: sealed capsules in two sizes.

8. Emplacement and Borehole Closure

9. Pre-disposal Activities

10. Construction of a borehole using percussion drilling

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

12. 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

13. Safety elements Can be linked to physical elements and assessments
Site selection
Safety functions
Limits and conditions
Mantainance requirements
Operational procedures
Emergency procedures
Management systems
Can be linked to physical elements and assessments

14. 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)

15. 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.

17. Additions for BDC
The user can define that one or more boreholes will be considered at a Site
A library of safety elements of relevance for BOSS will be added
A library of pre-disposal waste management activities relevant for BOSS
A library of processes

18. Additions for BDC A library of sources
SIMBOD – tool for management of the Borehole Disposal process
Typical waste streams – resulting from application of Typical Processes to different Types of Sources
Sources – Conditioned - Packaged

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

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

21. Graded approach to the assessments
Impacts
Calculations of Hazard Quotients (HQ) for standardized conservative
exposure situations
Screening or Hazards
calculations for specified endpoints and expecific exposure conditions
Dose Assessment

22. Assessments for accidents
PIE Type
PIE 1
PIE n
Scenario 1
Scenario n
Scenario m
Impact 1
Impact n
Impact m
Screening of hazards
Endpoint 1
Endpoint n
Ass Case 1
Ass Case n

23. 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

24. Additions for BDC Update of the PIE database
Library of typical scenarios
Library of generic safety assessments

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

26. 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)

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

28. 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.

29. Additions for BOSS
Models and calculation methods used in Generic Operational Safety Assessment (GOSA).
Parameter values required for GOSA.

30. SAFRAN components SPECIALIZED LIBRARIES FOR BOSS SAFREQ Report
System description
Site features, waste producers, waste streams
Safety Assessment
Normal operation, accidents
Report
Regulatory Framework
SAFCALC
DATABASE

31. SAFREQ
Tool for assistance in developing the safety case by assessing compliance with Safety Requirements and Safety Guidelines.

32. Additions for BOSS Going from a prototype to a Released version
Specific guidelines for safety case of BDC

33. GENERIC OPERATIONAL SAFETY ASSESSMENT (GOSA)

34. 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)

35. 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.

36. Scope
The starting point for the GOSA is that the Disused Sealed Sources (DSSs) have arrived at the site and a decision has been taken to “dispose” the DSS by borehole disposal
Activities of the original producer [e.g. hospital] and transport to site are beyond the scope of the current project).
Other disposal options (e.g. disposal in a near-surface or deep facility) and management options (long-term storage) are beyond the scope of this GOSA.

37. 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.

38. 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.
One issue currently under evaluation is whether to include assessment of doses to the eye, extremities, etc., in addition to whole body doses.

41. Typical activities and their duration
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
6) Encapsulation and test of the capsule
7) Place capsule in disposal container and NDT
8) Transfer disposal container to the transfer cask 10
9) Disengage and prepare the transport cask for transport
10) Emplacement of the disposal container in borehole
11) Backfilling of the borehole

42. 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.