A Probabilistic Risk Assesmsnet of an Underground Radioactive Waste Diposal Facilitiy

Abstract

A probabilistic risk analysis is demonstrated for a single groundwater release scenario from a hypothetical repository for intermediate level wastes situated in a clay layer at a depth of about 150 metres under Harwell. This is the first stage of development of an overall methodology which will eventually treat combinations of risks due to multiple release scenarios with parameter values whose uncertainty varies with time. It is shown that upper bound estimates of risk are unlikely to be useful and that the approach to radiological risk assessment based upon 'best estimates' is difficult to justify. Consequently, a full probabilistic risk analysis is necessary although further development of statistical sampling and data acquisition techniques and also of methods for the generation and analysis of site evolution scenarios, is necessary.