Purpose of the investigation under the Project – assessment of public exposure due to radionuclides migration in drinking water and soil of territories contaminated by uranium legacy and its modeling.
The subject of investigation is uranium legacy sites in the North of Tajikistan.
Tajikistan has a number of uranium ore deposits and mining and milling facilities, which operated in the past. This country’s own ores and imported raw materials were processed mainly at the former Leninabad Geochemical Combine facility (currently State Enterprise (SE) “Vostokredmet”) and also at other hydro-metallurgical plants located in the vicinity of uranium ore extraction sites (Adrasman, Taboshar, Isphara, etc.). Presently the only operating enterprise in the Republic of Tajikistan, which still has the potential to process uranium ores, using an acid leach extraction process, is the SE “Vostokredmet”. This enterprise is responsible also for storage and safe management of the 10 tailings facilities and waste rock piles which are situated in the vicinity of each of the former uranium facilities.
Based on estimates from SE “Vostokredmet”, the total amount of residual uranium in the tailings and waste rock piles in the Republic of Tajikistan is about 55 million tons. The total activity of these wastes is estimated to be approximately 240-285 1012 Bq. The total volume of waste rock piles and tailings in the vicinity of former hydrometallurgical plants and chemical-leaching sites is more than 170 million tons.
The waste rock piles and tailings at Taboshar, Adrasman and Degmay (which is on the outskirts of Chkalovsk) are not well covered. In particular the surfaces of the tailings usually have no protective cover; and the surface is eroded or damaged by burrowing animals. There is exposure of significant amounts of contaminants, which are subject to dusting and wind blow. Any cover of these tailings and waste rock piles has usually been washed away by water, mudslides and wind, thus becoming a source of highly contaminated drainage water which is migrating into surface and ground water bodies. The same sources of water are commonly used by the local population. In many areas where water is in short supply it is common to have livestock grazing and watering using such contaminated waters; also local horticulture uses these drainage waters for irrigation and even for rice paddies and orchards located near the sites of uranium waste piles.
Illegal excavation and collection of non-ferrous metals from areas of tailings and waste rock piles and mines has become more frequent. This creates serious concerns over transfer of contamination as well as the exposure of the individual diggers. There is concern that these metals are sold on at local, illegal, markets in Tajikistan or even transported abroad.
In this regard, the issues of assessment of public exposure due to radionuclides migration in drinking water and soil of territories contaminated by uranium legacy becomes very urgent and of high concern. Radiological assessment will be based on measurements of gamma-emission dose rate, gamma–emission spectrums on tailings’ and reprocessed uranium dumps areas, systematic measurements of Rn concentrations in dwellings, living spaces and environment, identification of basic natural radionuclides of uranium and thorium chain in ecological samples (materials of tailings, water, soil and air) as well as surface density contamination of territories by means of in-situ measurements. Measurements on underground water contamination will be also carried out around tailings.
It is planned to carry out assessment of radiation risks and threats due to tailings and to carry out its modelling. The exact degree of radiation danger will be identified for public and environment and recommendations will be developed on exclusion of site’s radiation impact. Measurements on putting into safe condition of radioactive wastes will be typified in relation to conditions of Central Asia. For achieving these purposes, it is planned to carry out complex investigations including fulfillment of physical, chemical, biological, hydrogeological, radiological and medical works as well as social observations.
It is expected that during project implementation, the radiation danger of radionuclides migration in drinking water and soil of territories contaminated by uranium legacy on public health and environment will be evaluated on the basis of investigation results and priority for immediate tasks on ensuring radiation safety of this site will be identified.
Proposed project is in full compliance with ISTC goals and facilitates to involvement of scientists and specialists, particularly weapons scientists, to international scientific and technical cooperation for solution of ecological problems and their integration to international scientific community for solution of remediation of contaminated territories by radioactive wastes (legacy sites).
The volume of works under the project is calculated for two and half years (30 months), with use of modern methods of physical, chemical, biological and medical experiments, application of computer technique for carrying out theoretical calculations, reprocessing and experimental data analysis as well as modeling.
For successful implementation of the project, its expertise, quality assessment and works results, rendering assistance in fulfillment of scientific and research as well as technological works and etc, the involvement of foreign collaborators with leading role is foreseen in this project. The project implementation is not possible without participation and consultations of these collaborators. It is also planned to involve scientists from Scientific and research institution Institute of nuclear problems” of Byelorussian State University which has a rich experience in radionuclides migration monitoring from Chernobyl accident.
The results of project can be used in contaminated areas close to Fukushima Daiichi Nuclear Power Plant.
