Probability distributions of dose conversion factors for radionuclides used in a long-term safety assessment

Abstract

The research presented in this report forms part of the PROSA (PRObabilistic Safety Assessment) project. PROSA aims to determine the radiological effects on humans and the characteristics relevant to safety of disposal concepts for radioactive waste in rocksalt formations. This report describes the modelling of the biosphere; the effects of the released radionuclides are described in nuclide-specific dose conversion factors. The dose conversion factors were determined for a biosphere where the radionuclides are released in a river via groundwater discharge. The river water is used as drinking water and for irrigation by a farmer who consumes only the product of his own land. For the calculation of the dose conversion factors the dynamic environmental transfer model, MiniBIOS, is used. The dose due to the ingestion includes the intake of drinking water, milk, cereals, leafy vegetables, root vegetables, meat and fish. Inhalation of resuspended soil and external exposure are also included. For most radionuclides the ratio of the minimum to the maximum value of the distributions is 1000 to 100,000. The ratio of the 10 percentile to the 90 percentile, however, is usually less than 500. The most important exposure pathways and sources of uncertainty were determined. An indication of the effect of other possible release points is given.