MONITORING OF GROUNDWATER CONTAMINATION WITH TRITIUM AFTER A RADIATION ACCIDENT AT A RADIOACTIVE WASTE DISPOSAL SITE

Abstract

The article analyses the data of long-term monitoring of the level of tritium contamination of groundwater in the area of the radioactive waste disposal site. Tritium is a radioactive isotope of hydrogen, a soft beta emitter. The impressive effect of tritium is due to the biological significance of the molecules into which it incorporates. Radioactive waste storage facilities store a lot of tritium-rich radioactive waste of various origins, a potential tritium source entering the natural environment. Any tritium released appears as tritium water (water that contains tritium in its molecules). Nowadays, the problem of tritium contamination of water ecosystems in the radioactive waste storage facilities’ areas can be considered one of the main issues in radioecology. The study aims to assess the level of safety of underground water in the radioactive waste disposal site area by the level of tritium content based on long-term monitoring data. The object of the study was the content of tritium in the underground water of the first aquifer in the territory of the radioactive waste disposal site (strict regime zone, sanitary and protective zone, and in underground waters of wells outside and in surface water bodies of the natural environment). We tested the tritium activity in water samples using the Triathler 425-034 liquid scintillation radiometer. In 1997, a radiation accident occurred at the radioactive waste disposal site. It led to the penetration of tritium into the first aquifer. Work has been underway to eliminate the accident. Modernisation of the system of wells for monitoring the underground water tritium contamination level also took place. As a result of the performed works, the radiation situation in the accident area has stabilised, and contamination of the aquifer due to the inflow of surface contaminated water from radioactive waste storage facilities has completely stopped. The results of long-term monitoring of tritium content in water of boreholes and wells and natural objects (reservoirs) located outside the sanitary protection zone of the enterprise showed that 27 years after the radiation accident, the radiation situation in the studied area is stable. The total activity of tritium in the aquifer of the monitoring wells is decreasing and has now reached the regulatory level in all but three wells. The concentration of tritium in underground waters (wells) and surface waters (reservoirs) outside the sanitary and protective zone has never exceeded the environmentally safe level during the monitoring period. At present, 89% of the studied monitoring sites (boreholes, natural reservoirs, wells) have tritium content that is within the environmentally safe range. Keywords: radioactive waste disposal site, radiation accident, tritium, aquifers, monitoring, environmental safety.