RD&D-Programme 2004 - SKB

14 Safety assessment
14.1 Methodology for assessment of long-term safety of
deep repository
An overview of the safety reporting during the site investigation phase is given in SKB’s plan of
action, see Appendix A. SKB’s work with safety assessments for a deep repository and method
and model development for them is being conducted during the site investigation phase almost
exclusively within the framework of the projects aimed at producing safety reports for the
applications for permits to build an encapsulation plant and a deep repository. The safety assessment
projects are called SR-Can and SR-Site. Of special importance for RD&D-Programme
2004 is the interim report for SR-Can that was recently published /14-1/. The purpose of that
report is to present the methodology for safety assessment prior to its use in the planned permit
applications. The report demonstrates not only completed methodology development with
examples, but also plans for how different problems are intended to be solved in the final report
for SR-Can. The regulatory authorities are carrying out a thorough review of the interim report
during the autumn of 2004 with the aid of a team of international experts.
Much of the relevant information on recent and planned development of safety assessment
methodology and tools are therefore presented in the interim report and are not repeated in
detail here.
Important method questions dealt with in the SR-Can Interim Report include:
• FEP processing and FEP database.
• Selection of scenarios.
• Handling of uncertainties.
• Sensitivity analyses.
• Risk calculations.
• Compliance with the regulatory authorities’ regulations SSI FS 1998:1 and SKIFS 2002:1.
In addition to the needs identified by SKB, the methodology development has also been based
on viewpoints on SKB’s most recent safety report SR 97 /14-2/ and on RD&D-Programme
2001, as well as requirements in the authorities’ regulations regarding safety reporting for a
deep repository (SSI FS 1998:1 and SKIFS 2001:1).
The point of departure for this chapter is KBS-3V, but it should be noted that the variant
KBS-3H with horizontal deposition of canisters is also being studied. SKB and Posiva are
together carrying out a programme which includes research, development and demonstration
of the variant KBS-3H with horizontal canisters, see section 10.7. Within the framework of the
programme, an assessment is planned of the long-term safety of KBS-3H. This will be carried
out under the leadership of Posiva, with the overall goal of presenting a safety assessment
for KBS-3H with Olkiluoto as the reference site in the middle of 2007. The idea is to utilize
as much as possible of the methodology that is being developed for the safety assessment
SR-Can. The results of Posiva’s own programme for research, development and demonstration
will naturally also be used /14-3/. The planned assessment includes a process report focusing
on processes that are specific for KBS-3H. Thermal, mechanical, gas-related and chemical
processes will be analyzed and radionuclide transport calculations will be carried out. The
planning report /14-4/ and the interim report /14-1/ that have been published within the SR-Can
project, as well as the planning report which Posiva will publish for its safety assessment for
KBS-3V, will be utilized in the planning of the safety assessment. Examples of steps included in
the planning work are preparing a preliminary table of contents for the assessment, identifying
the processes of importance for long-term safety that are common for the KBS-3H and KBS-3V
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