Forty-year evolution of radioactive groundwater contamination at the site of radioactive waste storage (St. Petersburg region, Russian Federation)

Abstract

Evolution of tritium and beta contamination plumes resulted from radioactive waste leakage in the 1990s has been studied based on 40-year-long monitoring data at the site of radioactive waste (RW) storage. Localand regional-scale hydrodynamics are found to be the main features controlling the spreading of tritium contamination in the aquifer system, while spatial distribution of beta-activity plume is strongly restricted by sorption of 90Sr и 137Cs isotopes onto rock matrix. The study performed proves that groundwater system at the site is actually in the stage of rehabilitation from the «historical» contamination. Special complex investigation program aimed on examination of water accumulated in repository buildings and its interconnection with groundwater, demonstrated good isolation of the buildings from the surrounding aquifers and no evidence of RW release to the subsurface environment nowadays.