RELIABILITY MODELING OF ENGINEERED BARRIER SYSTEMS FOR NUCLEAR WASTE - A CONDITIONAL APPROACH

The lifetime of the Engineered Barrier System (EBS) used for containme nt of high-level radioactive waste will play an important role in cont rolling the cumulative release of radionuclides from a geological repo sitory. Essentially, an EBS has two major components: a metal barrier and the waste form (cladding). Since any suitable site is above the st atic water table, the decay heat generated from this waste is expected to keep the surface temperature of a canister above the boiling point of water for a T random time period. Assuming the Weibull life-time d istribution on each component, we use the conditional approach to deri ve the lifetime distribution of the EBS. In our model, the oxidization process of the metal barrier (i.e. the lifetime of the metal barrier) starts after this time T and the lifetime of the cladding starts afte r the lifetime of the metal barrier.