Safety Problem of Techa River Reservoirs
Cascade of Water Reservoirs of Techa River: Problem of Safety
Tech Area / Field
- ENV-MRA/Modelling and Risk Assessment/Environment
3 Approved without Funding
IGE (Institute of Geoecology), Russia, Moscow
- NPO Mayak, Russia, Chelyabinsk reg., Oziorsk\nInstitute of Physics of the Earth, Russia, Moscow\nUral Branch of RAS / Institute of Geophysics, Russia, Sverdlovsk reg., Ekaterinburg\nIGEM (Geology & Mineralogy), Russia, Moscow\nGidrospetsgeologiya, Russia, Moscow
Project summaryThe objective of this project is to study the model of water balance and predict long-term changes of water level in the cascade of water reservoirs of the Techa River (TKV) which are used by PA "Majak" as a depository of low-level liquid radioactive waste (LLW). The project also includes a study of radionuclide transport to underground waters and elaboration of measures for the stabilization of water levels to prevent uncontrolled runoff of liquid LLW from the TKV and possible contamination of the environment.
The production cycle of PA 'Majak" generates a big volume of LLW. The waste is dumped into four water reservoirs, which are connected with one another. Presently TKV contains about 500,000,000 cu. meters of LLW. These reservoirs were built by banking up the existing natural water reservoirs in the Valley of the Techa River. To avoid direct penetration of radioactive waste into the Techa River, the river was split into two channels, which bypass the reservoirs from the two sides. The highest concentration of radionuclides is in the bottom sediment of the last TKV reservoir (B-11) which is the biggest one. The bottom and the walls of the reservoirs have no cement or asphalt covering. This causes a danger of penetration of radionuclides into the Techa River, channels and underground waters. Also, the water level in the last reservoir is only 0.5 meters below the allowable level. In case of unfavorable meteorological situation in snowy or rainy years, the contaminated water can spill over the reservoir walls or the dam, as well as seep through. The PA "Majak" area borders on the Central Ural seismic zone. Regional seismic activity may present an additional hazard for the stability of engineering barriers. It should be noted that the Techa River is part of the IsetV Tobol / Ob' / Irtysh river system which covers the Ural / Western Siberia region. Thus, the TKV LLW depository presents a problem for the entire region. To mitigate this environmental hazard it is necessary to develop adequate procedures for storage and management of radioactive waste, as well as undertake urgent prevention measures based on a comprehensive research.
The project presumes a development of the TKV water balance model as a basis for the risk mitigation plan. The preliminary estimates have shown that the lowering of water levels in TKV is the most efficient way of the hazard mitigation. However a detailed water balance for surface and underground waters is unknown. It determines by weather conditions as well as by filtration of water from the reservoirs to the underground hydrosphere, the river and the channels. Possible risk of penetration of radionuclides into the biosphere in case of accidents should be also estimated with the purpose to elaborate comprehensive prevention measures including methods and means of controlling the water balance as well as the creation of new engineering barriers.
The TKV Project draft-working program includes field research as well as the analysis and reprocessing of already existing data in the directions as follows:
- Carrying out experimental research to obtain new information on the following parameters:
- geological structure of the region and TKV zone;
- geophysical fields;
- regional tectonic, seismic and geodynamic manifestations;
- hydrogeological and weather / climatic conditions in the TKV region.
- Development and verification of the mathematical model of the TKV water balance.
- Computer simulation of possible critical environmental situations depending on conditions of reservoirs' filling up.
- Development of climatic scenarios for the period up to 2005 and longer. The observed alternation of series of low-water and high-water years will be taken into account.
- Development of long-term forecasts of variations of water levels in TKV.
- Development of methods of controlling the components of the TKV water balance to respond hazardous changes of water level in the reservoirs.
- Development of recommendations based on the model calculations and long-term forecasting to stop the trend to water level rise.
- Instrumental observation of regional seismic activity.
The expected results
- The TKV mathematical model.
- Structure and the content of the TKV water balance over the period of existence of the reservoirs.
- Long-term forecasts of water level variations in the B-l 1 reservoir.
- Recommendations methods and means of controlling the structure of the TKV water balance for stabilization and getting lower water level in the B-l 1 reservoir.
- Updated regional map of seismic zoning.
The proposed project is of great importance for both the Russian Federation and many industrial countries, which have nuclear facilities. Technological cycles at these facilities which manufacture or reprocess nuclear materials generate a big amount of LLW. Disposal and safety of LLW accumulated in these countries present a problem not only for these countries but also for the whole world. In case of accident it would be difficult to localize it within the zone of the nuclear facility because of the volume and mobility of LLW. The Chelyabinsk - 65 TKV, which is a unique, and one of the world's biggest depositories of LLW has been operated for decades. During this period Russian scientists have carried out long-term observations on the interaction of large open LLW reservoirs with surface and underground waters. Influence of meteorological factors on the water balance of the reservoirs has also been studied. Thus TKV presents a unique test site.
At the same time an urgent problem of TKV safety calls for international cooperation in research including the development of a comprehensive TKV mathematical model, as well as the use of advanced technological decisions. Methods and approaches to be developed in the project will have a practical importance for companies dealing with depositories of liquid radioactive waste. Data of long-term environmental observations at Mayak (Cheliabinsk-65) area could also have a commercial value. Interest in collaboration and willingness to participate in the project has expressed the British Nuclear Fuels pic (UK) and the Federal Institute for Geosciences and Natural Resources (Germany).
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