[Show abstract][Hide abstract] ABSTRACT: Brief analysis of design features and operational modes of Mayak PA industrial graphite-uranium reactors (PUGRs) is given. The above mentioned Mayak PA PUGRs determined the rates of releases of radioactive noble gases (RNG) from activation (41Ar) and fission (isotopes of Krypton and Xenon) through the vent stack of the reactor. Information is given on methods and results of experimental determination of RNG atmospheric releases for the period starting from 1965 till PUGRs decommissioning in 1987-1990. A calculation method for reconstruction of radioactive noble gas releases is proposed and justified. The results of reconstruction are given. It is shown that maximum rates of RNG releases from PUGRs high stacks were observed in the 1950s, when ordinary atmospheric air was used as a cover gas for the reactor graphite stacks and gas purification systems (flow-type gas holders) had not been installed yet.
[Show abstract][Hide abstract] ABSTRACT: The article provides the results of reconstruction of external doses to population due to atmospheric releases of inert radioactive gases of activation (41Ar) and fission origin (xenon and krypton isotopes) from the stacks of the “Mayak” PA industrial reactors from 1948 to 1989. Calculation of surface volumetric activities was performed using the RATCHET code. Dose estimate was obtained in a semi-infinite cloud approximation. It is demonstrated that more than 90% of external dose was accumulated from 1948 to 1956. It is established that, generally, the calculation results are in good agreement with archive instrument monitoring data on exposure dose rate and thermoluminescence dosimetry data. External effective doses to the residents of Ozyorsk obtained for different age groups of population with consideration of shielding properties of buildings and duration of time spent outdoors were estimated in the range from 16 to 23 mSv.
[Show abstract][Hide abstract] ABSTRACT: The method of reconstruction of 131I releases from the Mayak PA Radiochemical Plant stacks for the period from 1948 to 1967 is proposed and the results of reconstruction are given. During this period of time, no continuous routine experimental monitoring of release was performed. As a result, reconstruction was carried out on the basis of earlier obtained data on deliveries of 131I to the radiochemical plants with irradiated uranium from the Mayak PA graphite - uranium reactors. The reconstruction also used calculation - experimental data on the iodine distribution in process solutions and in ventilation exhaust gases from the radiochemical plants, as well as in archive information on the efficiency of iodine trapping with the help of gas purification facilities. Available experimental data on 131I releases from the stacks of the radiochemical plants are given. The reconstruction results are presented as average monthly and annual releases of 131I from the stacks of radiochemical plants B and DB. The results are intended to be used for estimating doses to the population living in the vicinity of the enterprise in the 1950s-1960s.
[Show abstract][Hide abstract] ABSTRACT: The article describes calculation procedure for reconstruction of radionuclide composition and activity of fission fragments accumulated in the irridated uranium from “Mayak” PA graphite-uranium reactors at the moment, when irradiation is completed, and at the moment, when the uranium is transferred to radiochemical processing (plant B) in the early 1950s. The procedure includes a reactor model and a cooling pool model. It is based on archive data on monthly uranium unloading and loading in the reactor and in the cooling pool of each reactor. The objects of reconstruction include: order of reloading of uranium versus its location radius in the reactor core; duration of irradiation and radionuclide composition of fission fragments for each radius; order of uranium removal from the cooling pool; effective time of uranium storage in the pool; radionuclide composition and activity of fission fragments in the irradiated uranium delivered to radiochemical reprocessing daily and on average for each month. The model is intended for use in reconstruction of parameters of radionuclide release source into the atmosphere and the source of liquid radioactive waste generation at the “Mayak” PA radiochemical plant.
[Show abstract][Hide abstract] ABSTRACT: The paper provides a short historical overview of creation, usage and current radiation and hydrologic status of the Techa
reservoir cascade. The analysis is given of the reservoir water balance, main water flows and sources of radionuclide filtration
inflow from the TRC into the open hydrographic system of the Techa river.
It is demonstrated that the main problem of the TRC usage is related to the general tendency of water level growth in the
reservoirs, which results in the increase of radionuclide inflow into the Techa river with filtration drains and forms additional
hydrostatic load on the dam of the end cascade reservoir R-11.
Different options increasing safety of the TRC use currently implemented and planned for the future are analyzed.
[Show abstract][Hide abstract] ABSTRACT: In-situ experiments for investigation of the heterogeneity of fractured aquifer rock were performed by Russian and American scientists in the area of the Mayak Production Association, South Urals, Russia, in 1996. This paper presents a description of the different hydrological and geophysical methods for acquiring and processing the data and a comparison of preliminary hydrogeological results. The coincidence of determinations of hydraulic conductivities, using different field tests and methods for data analysis, permits us to recommend the processes described for use in detailed investigations of the transmissivity of fractured-rock aquifers.
No preview · Article · May 2002 · Environmental Geology
[Show abstract][Hide abstract] ABSTRACT: The Mayak Production Association (MPA) is located in the northern part of Chelyabinsk Oblast. Operating areas are about 10 km from the town of Ozyorsk, the largest populated area nearby, but other nearby populated areas include Novogorny Village, New Metlino Village, and Kyshtym Town. The long-term objective of this (unfunded) project is reconstruction of the time-dependent individual radiation doses to residents of Ozyorsk and the surrounding area from atmospheric releases of radionuclides from the facilities of the Mayak Production Association (MPA). The time period is from 1948 to the present. This information could be used in several epidemiologic studies of the regional population. Two pilotscale studies of thyroid disease among residents of Ozyorsk have found an increase in thyroid nodules among exposed persons compared to unexposed persons and an increase in thyroid carcinoma in Ozyorsk. The success of follow-on studies would depend upon the availability of thyroid doses proposed to be provided. The availability of credible thyroid doses would allow the quantification of risk of thyroid disease and the evaluation of factors such as host susceptibility, age and time effects, and gender differences. Perhaps more importantly, studies of the Ozyorsk residents would not be encumbered with the complications associated with previous early detection screening, as in the Chernobyl studies, or previous medical conditions, as in the I-131 medical studies. The releases to the atmosphere from MPA stacks are a source of exposure to other populations that are the subject of epidemiologic investigation; these populations include the Extended Techa River Cohort (JCCRER Direction 1), the MPA workers (JCCRER Direction 2), and proposed studies of the East Urals Radioactive Trace (EURT) cohort. The doses received by these cohorts from atmospheric releases at the MPA represent a confounding variable that cannot be considered without the information proposed to be provided.
[Show abstract][Hide abstract] ABSTRACT: In the early 90's international organizations showed great interest
concerning the contamination problems at the PA "Mayak" territory, where
liquid radioactive wastes have been stored on the surface, including
Lake Karachay, reservoir "Staroye Boloto" and the Techa River cascade
reservoirs. As a result of this interest, international contracts funded
by DOE (USA), NRRA, EC and DGXL were instituted to study the experience
of radioactive waste management accumulated at the PA "Mayak" territory,
including proposed rehabilitation of the contaminated territories.
However, at the initial stage of international research, the works were
not coordinated and often duplicated each other, which was taken by the
public and mass media as a serious divergence of opinion between the
scientists on the risk assessment for the population. Many years of
research resulted in elaboration of a common scientific approach to the
solution of the problems of water resources contamination at the PA
"Mayak" territory. A successful experience of coordinating the
international projects to study radionuclide migration with surface and
ground waters at the PA "Mayak" territory is demonstrated, as well as
the risk assessment for the population. Substantiation for
rehabilitation measures can be based on long-term predictions and
modeling research that are continuing under these international
[Show abstract][Hide abstract] ABSTRACT: On the basis of appropriate laboratory experiments, energy release and composition of explosion products were determined for the accident that occurred at the Production Association “Mayak” (Chelyabinsk-40, Russia) in 1957. Based on archive data, quantitative characteristics of the formed radioactive trace structure have been specified up to a distance of more than 100km from the epicenter.
No preview · Article · Jan 2000 · Atmospheric Environment
[Show abstract][Hide abstract] ABSTRACT: The present paper describes results of the first independent evaluation of the accuracy of the dose-reconstruction technique by electron paramagnetic resonance using tooth enamel. Each of twenty-four teeth donated by Mayak nuclear workers with known occupational radiation exposure histories was cut into two parts so that each tooth could be shared for blind electron paramagnetic resonance examination by at least two of the four laboratories participating in the study. The mean difference (+/- SD) between electron paramagnetic resonance estimates of the paired samples of each tooth shared by the two laboratories in best agreement was 0.02 +/- 0.15 Gy. Mayak workers can be classified into two groups: modern workers (after 1961) having reliable official dose information and earlier nuclear workers whose dose information is less reliable because they were exposed mainly before 1961. Film badges did not contain filters until 1954. Doses in this earlier group are much higher (up to 5 Gy). Comparison of the electron paramagnetic resonance results with tooth doses calculated from official film-badge doses showed a close agreement for the first group, whereas in the second group, official doses appeared to be slightly higher than the electron paramagnetic resonance doses. The results suggested a possibility that the official doses were somewhat overestimated among the high-dose-exposed workers. Consequently, cancer risks derived from this high-dose group might tend to be slightly underestimated.
[Show abstract][Hide abstract] ABSTRACT: The Mayak Production Association (PA) in the southern Urals, Russia was the site of the first weapons-grade plutonium production reactor complex in Russia. The site and surrounding area have been significantly contaminated by direct discharges of radionuclides for over 40 years, the Techa River alone having received more than 100 PBq of waste in the period 1949–1956. The aim of this study was to consider the levels of 90Sr and 137Cs in water, sediment and biota samples for two industrial reservoirs in the Mayak PA area, thus allowing a biogeochemical assessment of the behaviour of radionuclides in the system. Four sediment cores were collected and sectioned along with four water samples and seven fish samples (pike, perch and roach). Samples were analysed using (i) standard gamma-spectrometric techniques (HPGe and NaI(Tl) detectors) for 137Cs determination; and (ii) radiochemical separation and beta-counting (low-background, anti-coincidence and Geiger–Muller counters) for 90Sr determination. Maximum specific activities (dry weight) of 3350 kBq kg−1 137Cs and 720 kBq kg−1 90Sr were measured in sediments from Reservoir 10. Activity levels of sediment-bound radionuclides in Reservoir 11 were 403 kBq kg−1 137Cs and 670 kBq kg−1 90Sr. Water concentrations in Reservoir 10 were as high as 100 Bq l−1 137Cs and 8.4–14 kBq l−1 90Sr. A dramatic decrease in 137Cs concentrations was observed in Reservoir 11, i.e. 1.1–1.5 Bq l−1, but 90Sr levels fell to a lesser extent, i.e. 1.9–2.4 kBq l−1. Sediment and water activity data allowed the calculation of distribution coefficients (Kd values). This parameter fluctuated for both radionuclides reflecting the heterogeneous nature of the sediment deposits in the reservoirs. Caesium-137 Concentration Factors (CFs) as high as 1400 l kg−1 were calculated for pike from Reservoir 10. A pronounced ‘trophic level’ effect was evident in Reservoir 11 (pike CF=1000, roach CF=240).
No preview · Article · Oct 1999 · Science of The Total Environment
[Show abstract][Hide abstract] ABSTRACT: A brief overview of the radioactive waste inventory of the 'Mayak' PA reprocessing plant, Chelyabinsk Region, Russia is given together with a description of the environmental contamination caused by its activities and the origins of contamination. The joint Russian-Norwegian field work in 1994 is described, together with the major analytical results. The field work was of a limited extent, and was not designed to include a complete mapping of the environmental contamination around the plant. The results are, however, in good agreement with the very extensive previous Russian investigations. The highest concentrations of radioactivity were found in Reservoirs 10 and 11 and at the floodplain of the upper Techa River (Asanov Swamp). Also high concentrations are found in biota, especially fish from Reservoir 10.
Full-text · Article · Sep 1997 · Science of The Total Environment
[Show abstract][Hide abstract] ABSTRACT: In September 1994, a Russian-American team conducted hydrogeological, geochemical, geophysical, and radiometric measurements
in the territory of the Mayak Production Association, Russia. The primary purpose of these operations was to examine the frontal
area of a radioelement- and nitrate-laden groundwater plume moving from the disposal site, Lake Karachai, toward the Mishelyak
River. Activities encompassed (1) isolation of hydrologic intervals in two wells and production of water from these intervals,
to compare isolated versus open-well sampling methods and to determine hydraulic transmissivities of the aquifer(s); (2) surface
and soil-water sampling, accompanying radiometric measurements and subsequent chemical analyses; and (3) electrical resistivity
profiling in areas of expected contrasting resistivity.
Preliminary results indicate that (1) 60Co, 137Cs, and 90Sr are present in small concentrations (∼0.1% of permissible levels) in water of the Mishelyak River; (2) analyses of water
samples collected by a downhole sampler and of water produced from packed-off intervals agree within limits of laboratory
accuracy, attesting to the efficacy of the sampling methods presently used by the Russian workers; (3) considerable differences
in contaminant concentrations exist between nearby wells, supporting the concept that the plume from Lake Karachai toward
the Mishelyak River is controlled by steeply dipping fractures and shear zones; and (4) strong contrasts occur between the
electrical resistivities of soil and bedrock.
Further collaborative work is strongly recommended and should include more detailed isolation of intervals in wells by multi-packer
installations, to better determine the geochemical and hydrological characteristics of the Karachai-Mishelyak system; deployment
of a broader soil water and soil sampling array; a more detailed examination of the distribution and concentration of radionuclides
by high-resolution field gamma spectrometry; and a detailing of the area's electrical resistivity setting, using a mobile
electromagnetic measurement system.
No preview · Article · Jan 1997 · Environmental Geology
[Show abstract][Hide abstract] ABSTRACT: Mean annual occupational exposures are reported for radiation workers at the first Russian industrial nuclear facility 'Mayak', South Ural region, for the period 1948-1988. The underlying individual doses originate from the register of the in-plant radiation safety department and are based on local film dosimetry results. Differentiation is made between personnel working at reactor and radiochemical processing plants. Verification of summed film doses is performed by means of ESR dose reconstruction using extracted teeth from selected individuals. Explanations are given for observed discrepancies between the reconstructed individual doses and original integrated film dosimetry results. The research potential of combined dose information from specific tooth enamel and dentine are shown.
No preview · Article · Nov 1996 · Applied Radiation and Isotopes
[Show abstract][Hide abstract] ABSTRACT: A group of scientists from the Savannah River Technology Center and Russia successfully completed a 17 day field investigation of a fractured rock aquifer at the MAYAK PA nuclear production facility in Russia. The test site is located in the western Siberian Basin near the floodplain of the Mishelyak river. The fractured rock aquifer is composed of orphyrites, tuff, tuffbreccia and lava and is overlain by 0.5--12 meters of elluvial and alluvial sediments. A network of 3 uncased wells (176, 1/96, and 2/96) was used to conduct the tests. Wells 176 and 2/96 were used as observation wells and the centrally located well 1/96 was used as the pumping well. Six packers were installed and inflated in each of the observation wells at a depth of up to 85 meters. The use of 6 packers in each well resulted in isolating 7 zones for monitoring. The packers were inflated to different pressures to accommodate the increasing hydrostatic pressure. A straddle packer assembly was installed in the pumping well to allow testing of each of the individual zones isolated in the observation wells. A constant rate pumping test was run on each of the 7 zones. The results of the pumping tests are included in Appendix A. The test provided new information about the nature of the fractured rock aquifers in the vicinity of the Mishelyak river and will be key information in understanding the behavior of contaminants originating from process wastes discharged to Lake Karachi. Results from the tests will be analyzed to determine the hydraulic properties of different zones within the fractured rock aquifer and to determine the most cost effective clean-up approach for the site.
[Show abstract][Hide abstract] ABSTRACT: The present investigation is devoted to the study of the distribution and geochemistry of contaminated subsurface waters, beneath the site of temporary storage of liquid radioactive waste known as Lake Karachai. For this purpose a method of hydrogeochemical logging (HGCL) together with standard hydrogeochemical and geophysical methods of uncased hole logging were used. The distribution of sodium nitrate brine plumes in the subsurface was determined by the physical and physico-chemical properties of these brines and by the petrochemical composition of enclosing rocks and the structural setting of the flow paths. The latter is represented by fractures and large faults in the bedrock of volcanogenic and volcanogenic-sedimentary rocks of intermediate-to-basic composition. The volcanogenic rocks are overlain in some places by a thin cover of unconsolidated sediments, i.e., by loams and relatively impermeable silts. Contaminated waters flow-in accordance with the eluvium bottom relief towards local areas of natural (Mishelyak and Techa rivers) and artificial (Novogomenskii water intake) discharge of subsurface waters. The large Mishelyak fault, southwest of Lake Karachai and under fluvial sediments of the Mishelyak, is assumed to significantly influence the flow pattern of contaminated waters, diverting them from an intake of drinking water.