RADIOACTIVE CONTAMINATION OF GROUNDWATER AT WASTE DUMP SITES IN CHERNOBYL EXCLUSION ZONE

• Date: 2020
• Main Authors: Bugai, D. О., Bayer, P., Haneke, K., Sizov, A., Tretyak, O., Kubko, Yu., Kireev, S., Molitor, N.
• Format: Article
• Language: English
• Published: Institute of Geological Sciences, NAS of Ukraine 2020
• Subjects: Chernobyl accident; strontium-90; cesium-137; groundwater; monitoring; 556.3.04 556.314
• Online Access: http://geojournal.igs-nas.org.ua/article/view/198438
• Journal Title: Geological journal

Results are presented of groundwater contamination survey of several waste dump sites in the 10-km zone of the Chernobyl NPP containing wastes from post-accident decontamination activities (e.g., “red forest“ destroyed by extreme radiation levels in 1986). Groundwater sampling in the immediate vicinity of waste burials using Waterloo Profiler push-drill system carried out in July — August 2015 has shown that the main hazard is related to groundwater contamination by strontium-90. Strontium-90 concentrations in groundwater ranged for different waste burials from 1.1 to 17800 Bq/l significantly exceeding the permissible activity concentration in drinking water of 2 Bq/L. Concentrations of cesium-137 in groundwater varied from values below the detection limit (<0.04 Bq/l) to 0.6 Bq/l (thus lower than the permissible activity concentration in drinking water of 2 Bq/l). Sampling results revealed that levels of radioactive contamination of groundwater by strontium-90at waste dump sites are relatively stable over the last two decades, which is consistent with the hypothesis of gradual dissolution of nuclear fuel particles in waste material, and release of radioactive contaminants to groundwater system. Lower levels of strotium-90 in groundwater were observed at “Neftebaza” waste dump site near the Pripyat Zaton surface water body, being likely caused by specific hydrogeological and geochemical conditions of this site (clayey soils; higher lateral groundwater seepage rates; reducing alkaline geochemical environment). The obtained data on radioactive contamination of groundwater in the immediate vicinity of waste burials with the help of the push-drill auger provide significantly higher levels of groundwater contamination in comparison to the data of the regime monitoring network of the Special State Enterprise “Ecocenter“, which is responsible for radiation monitoring in the Chernobyl Exclusion zone. This confirms that the existing system of hydrogeological monitoring of the waste dump sites in the 10-km zone of the ChNPP requires further improvement and development.