MATHEMATICAL-MODELING METHODS FOR ASSESSING RADIATION-DOSES RECEIVED BY POPULATIONS IN THE VICINITY OF A NUCLEAR SITE FROM ATMOSPHERIC DISCHARGES

This paper looks at some relevant work being done by the Ministry's Food Safety (Radiation) Unit in connection with obligations under the Radioactive Substances Act, 1960. MAFF, in conjunction with Her Majesty's Inspectorate of Pollution (HMIP) issues certificates of authorisation to nuclear sites to control operations and limit the environmental impact of discharges. Requirements in the UK now call for the current annual discharges from any one nuclear site to be limited so that no individual member of the public receives more than 0.5 mSv Committed Effective Dose Equivalent (CEDE) from all pathways. Doses to the general public should also be limited by the ALARA principle. From a knowledge of atmospheric concentration and deposition of the radionuclides, radiation doses via the foodchain, inhalation and immersion pathways may be calculated. Based upon this, the Authorising Departments are currently engaged in setting numerical limits to atmospheric discharges from sites in England and Wales. This paper assesses the likely radiation dose distribution via different pathways to critical groups from these discharges. Results are presented here of some recent investigations; in particular, the predicted doses received via food product and via radionuclide are examined to obtain possible useful insights. Methods for identifying the critical group and its location are fully explained as well as the results and methodology for the additivity of dose.