On radiocarbon and plutonium leakage to groundwater in the vicinity of a shallow-land radioactive waste repository

A shallow-land radioactive waste repository operated in boggy forest environment from 1963 to 1989. During the operation period, a considerable amount of technogenic radionuclides, in solidified state, was disposed into the vault established in the geological structure at the depth of up to 3 m. Environmental monitoring activities started after the closure of the repository in 1989. Recent investigations revealed transfer of radiocarbon and plutonium to the groundwater in the prevailing flow direction. Activity concentration of ^239,240Pu in non-filtered fraction of the groundwater from observation well no. 4 determined by alpha-spectrometry was 6.4 × 10⁻⁵ Bq l⁻¹ in 2005, and 3.2 × 10⁻⁴ Bq l⁻¹ in 2006. Further analysis of colloid-facilitated transport of plutonium is planned. Variation of ¹⁴C activity concentration in the same well was monitored in 2006. It varied from 0.2 ± 0.1 Bq l⁻¹ in October to 2.8 ± 0.6 Bq l⁻¹ in June and July. Results imply further research into radiocarbon transfer to atmosphere and selected plant species.