Assessment of plutonium contamination in the zone of influence of a radioactive waste storage facility

Abstract

Radioactive waste storage facilities (RWSF) are potential sources of radioactive contamination. The RWSF located in the Obninsk is one of the oldest in Russia. Between 1998 and 1999 was detected the leakage from storage tanks. There is no accurate information on the radioactive waste composition. Plutonium attracts special attention due to its long half-life and radiotoxicity. The purpose of this study is to assess plutonium contamination of environment in the RWSF zone of influence. The analysis of plutonium activity concentration in soil and plants was carried out using alpha spectrometry with preliminary radiochemical separation. It has been established that the area of contamination is limited to a 50 m zone from the border of storage. Plutonium concentrations in soil are observed down to 95 cm. Plutonium was detected in soils down to a depth of 95 cm. The irregular vertical distribution indicates migration via groundwater. Plutonium transfer factors to herbaceous vegetation ranged from 7.9·10⁻⁴ to 2.7·10⁻¹, with the highest uptake observed in the root systems. For shrubs, transfer factors ranged from 3.4·10⁻³ to 1.1·10⁻¹, with the highest concentrations found in berry clusters. In trees, transfer factors ranged from 1.5·10⁻⁵ in wood, to 1.3·10⁻² in needles, and up to 6.8·10⁻² in leaves.