Artificial radioactivity in Cumbria: summary of an assessment by measurement and modelling

At the Harwell laboratory, the distributions of the artificial radionuclides discharged by British Nuclear Fuels at Sellafield have been measured within Cumbria, with particular emphasis on the transfer between environmental media. The results of the measurements have been incorporated into a model of the Cumbrian environment. The object of this work is to estimate the radiological impact upon man by exploring the pathways leading to external irradiation, to inhalation and to the ingestion of foodstuffs. Distributions have been established for caesium-137, plutonium isotopes and americium-241. Transfer from sea to land, of actinide radioactivity discharged to the sea, occurs on a very small scale. The relative contributions to deposition and airborne radioactivity from sea-to-land transfer, fallout from nuclear weapons testing and atmospheric releases from Sellafield are compared. The dose resulting from sea-to-land transfer of actinides to a resident of Seascale peaked in 1973 at less than 1% of the ICRP annual limit for the general public and should fall steadily up to the year 2000. (author)