Quintessa

Geological Disposal of HLW & SF

AMBER has been used as a performance assessment tool for the geological disposal of High-level Waste (HLW) and Spent Fuel (SF).

For example, independent radionuclide transport calculations of the Swedish KBS-3 disposal concept were undertaken using AMBER as part of a regulatory review of both the SKB SR-Can and SR-Site assessments.  AMBER has also been used as part of the Finnish review of Posiva’s TURVA-12 assessment. The types of calculations included:

  • direct checks of specified SKB or Posiva calculations;
  • independent calculations to investigate particular aspects of the safety case.

For the SR-Can review, output from discrete fracture network (DFN) flow calculations were processed using path plotting software to provide input to the geosphere component of the AMBER radionuclide transport calculations.  These calculations produced very similar results to those reported by SKB for both the pinhole defect and lost buffer failure modes, and for both deterministic and probabilistic cases.

In the SR-Site review, modelling was undertaken to assess SKB’s analysis of the so-called “what if” and “residual” cases, which explore the role of the near-field barriers in providing safety by selectively removing them.   Overall, good agreement was shown between the AMBER calculations and SKB results for the key radionuclides.  The AMBER calculations undertaken for the TURVA-12 review helped to build confidence in the degree of cautiousness of Posiva’s calculations – here various “what if” scenarios were again considered to investigate the relative importance of the various components of the engineered barrier system, and to determine how many failing canisters could be tolerated.

AMBER was also used to develop independent biosphere models as part of the SR-Site review for SSM.  The findings of that review were presented at the Third International Conference on Radioecology and Environmental Radioactivity (ICRER) in Barcelona in 2014.

Image courtesy of SKB.