Some Aspects of the Prediction of Long-Term Performance of Fuel Disposal Containers

Abstract

The current status of a research program to evaluate the long-term performance of metal containers for the disposal of irradiated nuclear fuel in a deep hard-rock vault is reviewed. The primary objective is to develop a container failure function which can be used in the environmental and safety assessment of the disposal concept. Both short-term and long-term container failures are discussed. It is considered that an appropriate quality assurance program should enable a realistic estimate of the number of containers that will fail prematurely. In the longer-term, failures are most likely to be caused by timedependent metal degradation.For the passive candidate container metals, i.e. titanium, nickel-base alloys, crevice corrosion is the process most likely to limit container lifetime, whereas for copper, the supply of oxidants is expected to control the corrosion rate. An experimental program to determine the behaviour of candidate metals in a range of simulated disposal vault conditions is described. This program will form the basis for credible predictions of long-term performance.