ASSESSMENT OF RADIATION EXPOSURE FROM DISCHARGES OF URANIUM ORE CONCENTRATE PROCESSING AND NUCLEAR FUEL REPROCESSING FACILITIES

摘要

British Nuclear Fuels pic (BNFL) operates a uranium ore concentrate processing plant at Springfields, Lancashire, UK. The company is authorized to discharge naturally occurring beta and gamma emitting radionuclides into the nearby Ribble estuary that arise from the purification of uranium ore concentrates. The principal radionuclides identified are ~(234)U, ~(238)U, ~(228)Th, ~(230)Th, ~(232)Th and their decay products, ~(234)Th and ~(234m)Pa (from ~(234)Th decay). There are small amounts of artificial radionuclides which are discharged from the utilization of reprocessed uranium supplied by BNFL, Sellafield, principally ~(237)Np and ~(99)Tc. Radionuclides derived from Sellafield discharges, 80 km to the north, are also found in the Ribble estuary via transport through the Irish Sea, principally ~(137)Cs, ~(238)Pu, ~(239,240)Pu and ~(241)Am. The School of Ocean Sciences, University of Wales (Bangor), operates a well equipped radiochemical laboratory examining many aspects of natural and artificial environmental radioactivity in the marine and terrestrial environments. As part of a radiological assessment of the Ribble estuary for Her Majesty's Inspectorate of Pollution concentrating mainly on external and inhalation dose and leisure occupancy, beta dose equivalent and gamma air kerma rates were measured and surface sediment samples were taken at many sites during periods of both discharge and plant shutdown. Full results and methodology of this and previous studies of the Ribble River are presented elsewhere [1-5]. This paper presents a brief overview of the results obtained and discusses the local public perception that Springfields discharges are predominantly responsible for doses around the Ribble estuary, whereas the major contributor is Sellafield derived radionuclides.