Remediation and Assessment of the National Radioactive Waste Storage and Disposal Site in Tajikistan

Abstract

The National Radioactive Waste Storage and Disposal Site was established in 1959 in the Faizabad region approximately 50 km east of the capital, Dushanbe. The site is located on the southern flank of the Fan Mountains facing the Gissar Valley in a sparsely populated agricultural area, with the nearest villages located a few km from the site. The site was initially designed to accept a wide range of contaminated materials, including obsolete smoke detectors, sealed radioactive sources, waste from medical institutions, and radioactive liquids. Between 1962 and 1976, 363 tonnes and 1146 litres of material, contaminated with a range of radionuclides were shipped to the site. Between 1972–1980 and 1985–1991, ∼4.8 × 1014 and 2 × 1013 Bq, respectively, were shipped to the site. An additional 7 × 1014 Bq was shipped to the site in 1996. Partly as a result of the dissolution of the former Soviet Union, the disposal site had fallen into disrepair and currently presents both an environmental hazard and a potential for the proliferation of radionuclides that could potentially be used for illicit purposes. Remediation of the disposal site was started in 2005. New security fences were erected and a new superstructure over an in-ground storage site constructed. A central alarm monitoring and observation station has been constructed and is now operational. The geology, flora, and fauna of the region have been documented. Radiation surveys of the buildings and the storage and disposal sites have been carried out. Samples of soil, surface water and vegetation have been taken and analyzed by gamma spectrometry. Results show a slight extent of contamination of soils near the filling ports of the underground liquid storage container where a Cs-137 concentration of 2.3 × 104 Bq/kg was obtained. Similar values were obtained for Ra-226. Radiation fields of the in-ground storage site were generally <1 μSv/h with 8% exceeding this value. Neutron radiation levels at the same location were also low with a few readings exceeding 10 μSv/h. The volume of liquid waste is estimated to be ∼140 m3. Most of the activity appears to be associated with the sediments in the tank. Suggestions are presented for the immobilization of the liquid wastes and long-term monitoring of the site and the surrounding territory.