Probabilistic Safety Assessment for the Transport of Radioactive Waste to a UK Repository at Sellafield

Abstract

A study has been undertaken to provide a detailed understanding of the radiological and non-radiological risks associated with the transpott of radioactive waste from the sites at which waste is produced in the UK to a proposed deep repository at Sellafield, and to ensure that these risks meet the design targets specified by Nirex. The routine transport collective dose to members of the public was assessed to be 0.2 man.Sv per year, which is only about 0.004% of the natural background dose. Accident frequencies were calculated using event tree methodology. The radiological consequences of accidents were assessed using the probablistic computer code CONDOR. The risk expectation value was calculated to be 1.5 × 10^?5 ? 8.6 × 10^?6 latent cancer fatalities per year (depending on the transport mode scenario). These values are significantly lower than the corresponding prediciions for non-radiological accident fatality rates, 0.05 ? 0.035 fatalities per year. The radiological accident risk for the most exposed individual member of the public was assessed to be 5 × 10^?11 ? 1.7 × 10^?11 per year, very much less than the Nirex target of 5 × 10^?7 per year. Plots of societal risk were shown to lie in the region of ‘negligible risk’, as defined by the UK Health and Safety Commission for non-radioactive dangerous goods transport.