Analysis of barrier performance for a KBS-3 spent nuclear fuel repository

The goal of this project is to prepare for SSM’s future assessment of barrier performance and safety functions in the Swedish Nuclear Fuel and Waste Management Company’s (SKB’s) application for a KBS-3 spent nuclear fuel repository. The two safety functions which will be addressed in this work are the combined performance of near-field rock, buffer and canister to completely isolate the fuel, and the ability of the buffer and rock to retard radionuclide releases.

A critical safety function of a KBS-3 spent fuel repository is the ability of copper canisters to completely isolate the spent fuel for time periods exceeding 100 000s of years. The ultimate failure of canisters due to buffer erosion and/or copper corrosion should be addressed as the primary safety function. In this project an independent model should be developed to roughly estimate time periods for complete isolation of the spent fuel. Two basic model variations should be provided: a) a model in which the buffer retains its original ability to limit mass-transfer, b) a model in which transport conditions in the buffer may gradually change due to loss of buffer mass.

The radionuclide transport from a leaking canister through the buffer and bedrock to the biosphere should be addressed as the secondary safety function. This safety functions has been extensively analysed as part of previous safety assessment work, but the supporting calculations have normally neglected time variations of the flow-field and bedrock retardation properties. In this project the significance of these issues should be investigated using an independent radionuclide transport model.

A complete description can be found at http://com.mercell.com/permalink/23977327.aspx.