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Contamination Composition of the Ob'-Irtysh System

#1923


Comparative Evaluation of Input Weight of Radioactive Contamination Sources of Different Genesis In The Ob'-Irtysh River System

Tech Area / Field

  • ENV-WPC/Water Pollution and Control/Environment
  • ENV-MRA/Modelling and Risk Assessment/Environment

Status
3 Approved without Funding

Registration date
10.07.2000

Leading Institute
VNIITF, Russia, Chelyabinsk reg., Snezhinsk

Supporting institutes

  • National Nuclear Center of the Republic of Kazakstan / Institute of Radiation Safety and Ecology, Kazakstan, Kurchatov\nInstitute of Plants & Animals Ecology, Russia, Sverdlovsk reg., Ekaterinburg

Collaborators

  • [Individual specialist]\nRiso National Laboratory / Nuclear Safety Research and Facilities Department, Denmark, Roskilde\nCanberra Packard Trading Corporation, USA, CT, Meriden\nUniversity of California / Department of Radiological Sciences, USA, CA, Davis

Project summary

World experience of natural science and technological progress is evidence of the close interconnection between regional and global ecology problems. A thin multibranch network of biosphere phenomena ties continents and mainlands together into a single whole. In this integrity the Ural-Siberian region has a special place due to its outlet through major waterways to the North Seas and the Arctic Ocean, with its hard relief shapes, and varied latitudinal zonality with simultaneous massive radionuclide and chemical contamination. A leading transport waterway of this region is the Ob-Irtysh system that incorporates such large-scale rivers as the Ob, Tobol, and Irtysh, including their numerous inflows. The huge drainage area (2.9 million km²) of this system is a supplier of natural geo-chemical materials and man-caused pollution agents at unloading sites where sludge liquors are accumulated. These sites are natural biogeochemical barriers: floodplains, rubbish lakes and waterlogged estuaries.

A number of rivers of the Ob-Irtysh system (the Pyshma, Techa, Iset, Tura, Shagan, and Tom) were affected by enterprises of the military-industrial and nuclear power complexes. The standard operating procedures of such enterprises with its initial activity involving imperfections in implemented technologies, and subsequent emergency situations resulted in contamination of waterways and adjacent natural-territory complexes. Thus, the multi-year nuclear tests at the Semipalatinsk Testing Site were accompanied by the emission of radioactive substances into the environment both by air and by water flow from the intermittent river Shagan. A considerable contribution to the radioactive contamination had been and continues to be made by the Techa and Iset rivers. During the first years of the nuclear program (1949-1952) liquid radioactive wastes from Production Enterprise “Mayak” (PO “Mayak”) were released into the Techa at 6km from its head. 76*106m³ of wastes of total radioactivity 1017 Bq were discharged within this period. These wastes included long-life radionuclides 90Sr and 137Сs that constituted 11.6% and 12.2% correspondingly ("Conclusion"…, 1991). With account of radioactive decay, the current content is estimated as 4.3·1015 Bq for 90Sr and 4.6·1015 Bq for 137Сs.

In 1951-1964 a cascade of artificial water-storage reservoirs, involving by-pass channels and already existing ponds, was built in the region of the Upper Techa. This system has limited the radionuclide inflow into the river, but, by that time the most part of the floodplain and the bottom of the river had been substantially contaminated. A migration of radioactive substances from the cascade of water-storage reservoirs and by-pass channels was also detected. Lake Karachai is situated close to the production site of PO "Mayak", and middle- and high-level radioactive wastes have being released into it over a considerable period of time. As a result a water lens was shaped from the radioactive waters that moved along the water-flow vector, encompassing the watercourse of the Techa River. This circumstance testifies that there is possible radionuclide inflow from Lake Karachai to the Techa River through springs.

Along with gas-aerosol and liquid blowouts, some amount of fuel fission products (90Sr, 137Cs, 144Ce, and etc.), nuclides of induced activity (59Fe, 60Co, 65Zn, etc.), and natural and transuranium elements, are released in the process of nuclear power plant operation. One such power plant is the Kurchatov Beloyarskaya Nuclear Power Plant (BNPP) located in the Middle Urals, 60km from Yekaterinburg. One of the critical ecosystems within the BNPP area is the Ol'khovskaya marsh-river ecosystem, which has been subjected to a multi-year release of low-level radioactive unbalance waters from the plant. This system includes the waste (outlet) channel, the Ol'khovskkoye Marsh and the Ol'khovka River that flows out of the marsh and into the Pyshma River.

It was shown that the bottom sediment of the marsh has accumulated about 100 Cu of 90Sr, 60Co, and 137Cs. About 2% of their total content flows out annually from the Ol'khovka River and into the open hydrographic network. This, along with the existing shift of maximum radionuclide concentration in bottom sediments by the water-flow vector, gives grounds to forecast a potential generation of radioactive contamination agents in the Ob-Irtysh River system. The set of radionuclide contamination sources of the Ob-Irtysh River system, via the River Tom, also includes the Siberian Chemical Combine Tomsk-7.

It also should be noted that underground nuclear explosions have been conducted on the territory of the Khanty-Mansiisk National District to increase pressure in oil-beds. The possibility of radionuclide migration in surface and underground waters to the Ob-Irtysh River system should be assessed.

With time localized and regional radioactive contamination acquires priority ecological importance against the background of overall environment contamination caused by global radioactive atmospheric precipitation. This stipulates the need to conduct deep prolonged radio-ecological research in key regions and critical sections of the Ob-Irtysh River system.

Based on the above information, the objectives of the project are:


1. Quantitative evaluation of input weights of various radioactive contamination sources of the Ob-Irtysh River system (global precipitation, production activity of PO “Mayak”, Siberian Chemical Combine "Tomsk-7", and Semipalatinsk Test Site).
2. Development of radiation environment forecast for the Ob'-River estuary under present radionuclide migration and in the case of emergencies.

To achieve the formulated objectives, the solution of the following tasks is supposed:


1. Development of Work Schedule for the project, involving coordination of the final Research Program.
2. Sampling with geographic fixing.
3. Laboratory analysis of all samples:
a) g-spectrometry (100% of 137Cs sampling volume)
b) a-spectrometry (10% of 239/240Pu sampling volume)
c) b -radiometry (25% of 90Sr sampling volume)
4. Evaluation of input weights of various contamination sources by isotopic ratio method.
5. Development of a prognostic model for optimum and worst-case situations. Summary of existing and obtained results. Preparation of a conclusion and documentation required.

The Project results will have great scientific and applied importance, as they may be used to assess changes in the radiation environment in different areas of the river basin, which take place in the case of emergency situations at nuclear power and atomic facilities or due to large-scale natural processes and phenomena.

Project realization will also allow a socio-economic effect to be obtained. It will reveal itself in rational structural organization of economic complexes, development of a social protection and psychological rehabilitation system for the population of environmentally unfavorable regions, preservation of health and the gene pool of isolated ethnic groups inhabiting the territory under investigation, and of the nation as a whole.

To date, the employees of the Continental Radio-Ecology Department at UB RAS/IPAE, in cooperation with National Laboratory RISO (Denmark), have conducted intensive investigations of the radio-ecological situation in basins of the Techa and Iset, contaminated due to discharges from PO "Mayak".

ATC VNIITF is almost completely equipped with radiometric and spectrometric equipment, including mobile laboratories. Specialists have considerable experience in investigations of the radio-ecological environment at various sites (e.g., territory of Timofeev-Resovsky Laboratory “B”, territory of the Eastern-Urals Radioactive Trace (EURT) located in Chelyabinsk and Sverdlovsk Regions, etc.)


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