Public exposure formed by atmospheric discharges of nuclear power plants in ukraine

Abstract

Ukrainian Radiation Protection Institute has developed system for calculation of doses to the population living in the supervision zone of the NPP from atmospheric discharges of Nuclear Power Plants during normal operation. The system analyses daily meteorological data, and also daily and monthly atmospheric discharges of radionuclides. The developed system is applied for dose calculation for Ukrainian population and identification of radionuclides, which form considerable contribution to total doses (noble gases, H-3, I-131). A special attention has been given for variability of actual meteorological conditions and discharges. For example, it has been revealed the case when I-131 discharge from a Ukrainian NPP during 4 consecutive days has made 34 % of annual discharge (and 72% during 3 weeks). Variability of actual discharges is a result of changes in an operation mode of NPP unit and it is a typical situation for Ukrainian NPPs. Apparently, the similar situation can be typical for NPPs in another countries. Such results lead to necessity to consider possible variations of meteorological conditions and discharges for establishment of permissible levels (for example, by introduction of variability factor).