The Impact of Performance Assessment on the Experimental Studies at Aspo Hard Rock Laboratory and on future Site Characterization and Evaluation in Sweden

摘要

The SKB method for disposal of spent nuclear fuel is denoted the KBS-3 method. The repository system, located at about 500 m depth in crystalline rock, includes engineered and natural barriers which co-function to isolate the waste from the biosphere during the time span in which the waste constitutes a potential hazard, roughly 100 000 years. The spent fuel elements will be encapsulated into a copper-coated steel canister surrounded by a layer of bentonite clay. At existing favourable chemical and mechanical conditions the canister will remain intact for several million years. Despite this, an important scenario for the safety assessment is the malfunction of the system, which could cause a leakage of radionuclides from the repository, and migration of some of them up to the biosphere. For the assessment of that scenario, models are made to describe how corrodants could be transported to the canister and subsequently, how radionuclides could be transported from a leaking canister. However, the corrosion process of the canister itself has the largest impact on the outcome of this scenario [SR 97].