The transfer of natural (226Ra, 232Th, 40K) and artificial (137Cs, 90Sr) radionuclides from soil to the wood of a Scots pine (Pinus sylvestris L.)

Abstract

On the Stabatishke site near to Ignalina Nuclear Power Plant a near surface repository for low and intermediate-level short-lived radioactive waste is being constructed to store the waste which was produced during the decommissioning of the Ignalina Nuclear Power Plant. A possible spread of radionuclides from the near surface repository and the radiation level of expression are one at the most important aspects while evaluating the safety of the repository. The article examines the specific activity of artificial (137Cs, 90Sr) and natural (226Ra, 232Th, 40K) radionuclides in the soil of Stabatishke site of Ignalina NPP in pinewood; the spread of these radionuclides is determined in the system “soil-tree”. The change of long term soil pollution with artificial radionuclides was estimated. This is a background soil pollution which had been there before the exploitation of the near surface waste repository. The transfer factors of natural (226Ra, 232Th, 40K) and artificial (137Cs, 90Sr) radionuclides from the 0-to-20-cm soil layer to different annual pinewood rings were measured. After estimation of the position of pine roots in accordance to the soil vertical and the annual change of the plant biomass, the transfer factor of 137Cs movement to different annual pinewood rings from the separate 0 to 20-cm soil layers was determined.