Study of near-ground radionuclide concentration distribution in the Ignalina NPP district

In the course of nuclear weapon testing a great amount of fission products has been released into the atmosphere, thus the long-living radionuclides are still present there contributing to the radiation conditions near the NPP. Often the concentrations of radionuclides released during the reactor operation are comparable with the global background levels. The latter were studied in Ignalina NPP district since 1978. Sampling was done via air pumping through filters at 2000 m3/h rate. The sample gamma activity after filter incineration was determined with the use of spectrometer with Ge(Li) semiconductor detector. Time dependence of berillium-7 and caesium-137 concentrations over period of three years has been obtained. The evaluations of radionuclide concentration distributions connected with the NPP releases show substantial difference from the background concentrations