Kyshtym Accident Research Articles

Recent Levels of Radionuclide Contamination in the Eastern Ural Radioactive Trace and Biological Effects in Local Populations of Plantago major L.

The results of the study have shown that the stocks of 90Sr and 137Cs in the frontal part of the EURT are 6700–15000 and 200–400 kBq/m2, respectively. The coefficients of their accumulation in different herbaceous plant species in this impact zone are lower than in other areas. The accumulative capability of plants has probably decreased in the course of selection as an adaptation to the effect of radiation. The viability and growth parameters of Plantago major L. seeds from the EURT zone are similar to those of seeds from the background sample. Cenopopulations chronically exposed to radiation are characterized by a higher mutation rate in the progeny and an unstable response to additional acute irradiation in most characters studied. A high level of inbreeding is observed in all P. major cenopopulations of plantain. The cenopopulation of the impact zone is characterized by a lower variation of allozyme loci, which may be a result of stringent selection for individuals better adapted to the complex of conditions existing in its habitat.

Phenogenetic Analysis of Pygmy Wood Mouse (Apodemus uralensis Pall.) Populations in the Zone of the Eastern Ural Radioactive Trace (EURT)

Monitoring of A. uralensis populations in Kamenskii raion, Sverdlovsk oblast, in 1992–2002 and in Kaslinskii raion, Chelyabinsk oblast, in 2000–2001 revealed an increase in the proportion and diversity of minor morphogenetic aberrations and abnormalities in the structure of the cranium along the axis of the Eastern Ural Radioactive Trace (EURT). The samples from the southern and northern parts of the EURT (contaminated with 90Sr to 500 and 4 Ci/km2, respectively) were characterized by directed deviations from the control with respect to the frequencies of phenes of nonmetric cranial traits and an increase in the level of their fluctuating asymmetry in young females, which is indicative of epigenetic rearrangements in populations living in a radioactive environment.

Radionuclides in the ecosystem of Lake Tygish in the zone of the Eastern Ural Radioactive Trace

The radioecological situation in Lake Tygish is described. The lake is situated on the central axis of the Eastern Ural Radioactive Trace (EURT), which was formed after the nuclear accident in the Southern Urals in 1957. The distributions of 90Sr and 137Cs among the main components of the water body and the results of the measurement of tritium concentration in the water are presented. Mathematical models are described that have made it possible to estimate changes in the concentrations of radionuclides and their amounts accumulated in the water and bottom sediments of the lake during the long period after the accident and to predict the development of the radioecological situation in the lake until 2057. Based on the mathematical models, more accurate data on the initial ecological situation in the lake in the year of the accident have been obtained.

Model reconstruction of 90Sr concentrations in fish from 16 Ural lakes contaminated by the Kyshtym accident of 1957

The paper outlines the results of the ECOMOD model application to simulate 90Sr dynamics in fish dwelling in Southern Ural lakes and contaminated as a result of the Kyshtym accident. The detailed reconstruction of 90Sr behavior in fish for the 40-year period (1957–1997) was made for the most contaminated lakes (Uruskul and Berdenish). The adapted ECOMOD model was applied for the other 14 Ural lakes to explain the peculiarities in 90Sr accumulation by fish in lakes with different concentrations of Ca2+ ions in lake water.

Studies on the Ozyorsk population: dosimetry.

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 withmore » 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.« less

Determining factors causing disturbance of adaptation mechanisms in residents of radiocontaminated territories in the Ural region

Work was carried out in the East-Ural Radioactive Trace area and the Techa river valley, to which liquid radioactive waste was drained. Data on the state of health and health loss risk factors for residents of these territories were gathered. With regard to the state of health, data are available of clinical examination by a medical specialist, with assessment of the state of organism principal systems (cardiovascular, bone- muscular, nervous, etc.), and data on human organism pre-nosologic indicators. With regard to the risk factors, data are available on single individuals' residence, bad habits, traits of character and way of life, unhealthy work conditions, etc. These data have been entered in a computer database listing 1500 individuals. The present report outlines the results of analysis of the effect of various risk factors on pre-nosologic indicators (indices of the state of human organism adaptation systems). It is shown that, for residents of the Techa river basin, maximum influence on disturbance of adaptation mechanisms (Regulatory systems activity indicator, or RSAI) is exerted by such factors as: age, water supply characteristic, excessive weight. The fact of living on a radiocontaminated territory has no direct influence on RSAI; however, there are signs of indirect influence of the place of residence on RSAI, which are: varying dependence of RSAI on age in test and control groups, and combined effect of the water supply characteristic and place of residence on RSAI. In case of the inhabitants of the East-Ural Radioactive Trace area, there is revealed a noticeable influence of the accumulated dose on disturbance of adaptation mechanisms. Such influence has been detected within homogeneous population groups picked out by such features as: bad habits, harmful location factors, unfavourable conditions of work, etc.

A general approach to transform a lake model for one radionuclide (radiocesium) to another (radiostrontium) and critical model tests using data for four Ural lakes contaminated by the fallout from the Kyshtym accident in 1957

This paper presents results of a model test carried out within the framework of the COMETES project (EU). The aim of the work was to change the structure of the MOIRA lake model for radiocesium so that it can be applied more generally for, in principle, all types of radionuclides and heavy metals. This general lake model is used within the MOIRA decision support system (DSS; MOIRA and COMETES are acronyms for EU-projects). The model is based on a set of differential equations and a specific modelling structure. It incorporates all important fluxes to, from and within lakes in a general manner. Yet the model is driven by a minimum of variables accessible from standard maps and monitoring programs. The model can be separated into two parts, a general part with equations applicable for all types of water pollutants and a substance-specific part. This model has previously been validated for 137Cs from many lakes covering a wide domain and yielded excellent predictive power. The alterations discussed in this work are meant to be general and radiostrontium is used as a typical element. Radiostrontium is known to be more mobile than radiocesium and all abiotic parts of the model handling fixation and mobility have been altered. The new model for 90Sr has been critically tested using data from four lakes heavily contaminated with 90Sr from the Kyshtym accident in the Southern Urals, Russia, using empirical data from a period from 1958 to 1995 for 90Sr in fish (here goldfish), water and sediments.

Quantitative assessment of the long term behaviour of 90Sr in Lake Uruskul, Southern Urals, Russia

The present paper is aimed at assessing the long term behaviour of 90Sr migration from water to bottom sediments of Lake Uruskul, Southern Urals, Russia. The lake was contaminated following the nuclear accident at the Mayak nuclear complex in 1957 (the Kyshtym accident). Some transfer parameters relevant to the behaviour of 90Sr in the water–sediment system were evaluated: a) the radionuclide migration velocity from the water column to the bottom sediment, b) the radionuclide migration rate from bottom sediment to water, and c) the radionuclide migration rate from bottom sediment to deep sediment. The estimated values of the above parameters were 6.4×10 −8 m s −1, 5.7×10 −10 s −1 and 5.2×10 −10 s −1, respectively. These values were compared with data obtained for some Italian lakes contaminated by 90Sr after the nuclear weapons tests fallout. The relatively low radionuclide migration from water to sediment of these lakes is reflected by the values of the ratio migration velocity/migration rate from sediment to water (4 m and 12 m) that are significantly lower than the corresponding value in the Russian lake (112 m). The peculiar hydrochemical conditions of Lake Uruskul (high pH, high mineralisation, etc.) are considered to be responsible for the high radionuclide migration from water to sediment.

Comparative Evaluation of Prooxidant/Antioxidant Balance in Seed Progeny of Plantago major L. from Radioactively and Chemically Contaminated Areas

There are many studies addressing plant responses to radioactive and chemical contamination of soils, but few works have been devoted to comparison of biological effects in the areas affected by these human-induced factors. Ionizing radiation and heavy metals have different mechanisms of interaction with biota. Both factors, however, are capable of increasing the generation of reactive oxygen species, which cause enzyme malfunction and cell structure damage. The efficiency of antioxidant systems plays an important role in plant resistance to these impacts. The present study offers a comparative evaluation of prooxidant/antioxidant balance in seed progeny of Plantago major L. growing in the East Ural Radioactive Trace (EURT), in the zone affected by operation of the Karabash Copper Smelter (KCS), and in the reference sites. Lipid peroxidation was assessed by determining malondialdehyde. Evaluation of the antioxidant system was based on the activities of superoxide dismutase, catalase, and total peroxidase, and on the content of low-molecular-weight antioxidants. The study showed that the prooxidant and antioxidant statuses of seed progeny of P. major from the contaminated sites were different from the reference samples and from each other. The pooled EURT sample exhibited a prooxidant shift relative to the reference samples, i. e. not only malondialdehyde but also activities of superoxide dismutase and catalase and the content of low-molecular-weight antioxidants were higher than in the reference samples. Malondialdehyde content in seedlings from the KCS zone did not differ from the reference values; superoxide dismutase and catalase activities were decreased whereas peroxidase activity was higher compared to the activities of these enzymes in the reference samples. Thus, the differences in the plant adaptive responses to ionizing radiation and heavy metals are caused by the dissimilarities in the induction of reactive oxygen species

A blind test of the MOIRA lake model for radiocesium for Lake Uruskul, Russia, contaminated by fallout from the Kyshtym accident in 1957

This paper presents results of a model-test carried out within the framework of the COMETES project (EU). The tested model is a new lake model for radiocesium to be used within the MOIRA decision support system (DSS; MOIRA and COMETES are acronyms for EU-projects). This model has previously been validated against independent data from many lakes covering a wide domain of lake characteristics and been demonstrated to yield excellent predictive power (see Håkanson, Modelling Radiocesium in Lakes and Coastal Areas. Kluwer, Dordrecht, 2000, 215 pp). However, the model has not been tested before for cases other than those related to the Chernobyl fallout in 1986, nor for lakes from this part of the world (Southern Urals) and nor for situations with such heavy fallout as this. The aims of this work were: (1) to carry out a blind test of the model for the case of continental Lake Uruskul, heavily contaminated with 90Sr and 137Cs as a result of the Kyshtym radiation accident (29 September 1957) in the Southern Urals, Russia, and (2) if these tests gave satisfactory results to reconstruct the radiocesium dynamics for fish, water and sediments in the lake. Can the model provide meaningful predictions in a situation such as this? The answer is yes, although there are reservations due to the scarcity of reliable empirical data. From the modelling calculations, it may be noted that the maximum levels of 137Cs in fish (here 400 g ww goldfish), water and sediments were about 100,000 Bq/kg ww, 600 Bq/l and 30,000 Bq/kg dw, respectively. The values in fish are comparable to or higher than the levels in fish in the cooling pond of the Chernobyl NPP. The model also predicts an interesting seasonal pattern in 137Cs levels in sediments. There is also a characteristic “three phase” development for the 137Cs levels in fish: first an initial stage when the 137Cs concentrations in fish approach a maximum value, then a phase with relatively short ecological half-lives followed by a final phase with long ecological half-lives more or less corresponding to the physical decay of radiocesium.

Analysis of local dandelion (Taraxacum officinale s.l.) cenopopulations from radioactively contaminated zones.

Local dandelion ( Taraxacum officinale s.l.) populations were studied in the areas of the Eastern Ural Radioactive Trace and the floodplain of the Techa River in its upper reaches. In impact plots, the density of soil and plant cover contamination with 90 Sr and 137 Cs exceeded the background level by factors of 13-440 and 2-500, respectively; the radiation load exceeded the background level by factors of 1.5 to 45. The seed progeny of plants from these plots was characterized by a high proportion of abnormal seedlings and an increased level of chromosome aberrations in meristem cells. In some years, variation in the seedling viability, growth rate, and developmental rate in these plots exceeded the reaction norm of plants from the background plot, demonstrating both stimulation and inhibition of growth processes. The response of seeds to acute irradi- ation at high challenging doses varied depending on the level of background radiation in the plots.

Trophic specificity of theRana arvalis population from the eastern ural radioactive trace in relation to the state of the soil mesofauna

Studies on the population ofRana arvalis Nilss. frogs performed in the radioactively contaminated area near Lake Berdanish in 1993 revealed a number of features indicating that the contents of nutrients in the organisms of adults and juveniles is low. The analysis of simultaneously collected data on food supply to this population showed that the structure of food chains in the study area is simplified and the diversity and biomass of soil invertebrates (the main food for amphibians) are sharply reduced. These factors account for food deficiency, which manifests itself in a low level of stomach filling and individual energy reserves of the frogs and is reflected in their population characteristics.

Environmental contamination and assessment of doses from radiation releases in the Southern Urals.

The Southern Urals in Russia was contaminated by radioactive discharges into the Techa River (1949-1956), the Kyshtym accident (1957), and the current releases and discharges from the Mayak Nuclear Materials Production Complex. In this paper, the consequences of radioactive contamination of the Ural region are analyzed. The current content of 90Sr in the components of food chains is as follows (Bq kg(-1) wet weight): potatoes, 0.2-6.7; grain, 0.5-12.6; milk, 0.2-6.3; beef, 0.2-1.7; lake water, 0.12-1.0; river water, 0.2-8.5; fish, 7-480; mushrooms, 400-1,100; and berries, 700-16,000. The content of 137Cs is as follows: potatoes, 0.5-3.8; grain, 0.3-2.9; milk, 0.2-4.5; beef, 0.3-2.6; lake and river water, 0.002-0.019; fish, 2-32; mushrooms, 110-1,600; and berries, 150. A major fraction of the dose to humans comes from the consumption of local food products, including natural ones, which have higher contamination levels than agricultural products. The average annual dose rates in contaminated areas are (0.5-4) x 10(-4) Sv y(-1), which is lower by a factor of 10(2)-10(4) than in the periods of "acute" exposure (1950-1951 and 1957-1958). Natural organisms received very high doses up to 200-800 Gy resulting from radioactive discharges into the Techa River and the radiation accident in 1957. In all cases, including the "acute" exposure followed by the chronic irradiation, the doses to biota were by a factor of 10-10(3) higher than those to humans.

Isotopic Pu, U, and Np signatures in soils from Semipalatinsk-21, Kazakh Republic and the Southern Urals, Russia

Mass spectrometry measurements of Pu, U and Np isolated from soils contaminated by the 1957 accident at the Mayak nuclear complex in the Southern Ural mountains (‘Kyshtym accident’) and from soils collected at and near the Former Soviet Union (FSU) test site at Semipalatinsk-21 are reported. The results provide a coherent isotopic data set suggesting (1) that Pu recovered from irradiated uranium fuels processed at Mayak formed the source material for Pu devices tested at Semipalatinsk-21; (2) that 237Np in the breached Mayak storage tank resulted, principally, from enrichment of this radionuclide in waste streams during the processing of low burn-up uranium fuels to recover both Pu and U and (3) the presence of 236U at both sites may be useful in tracing inputs of this, and other transuranic radionuclides, to nearby river systems that flow to the Arctic Ocean.

Radioactive inventories from the Kyshtym and Karachay accidents: estimates based on soil samples collected in the South Urals (1990–1995)

The implementation of the nuclear programme in the Cheliabinsk region in the Ural, where plutonium for the first Soviet nuclear weapons was produced, involved radioactive contamination of the environment. The end of the cold war in the late 1980s initiated a fruitful co-operation between Russian and Western radioecologists. The present study is a joint Russian-Ukrainian-Danish effort to make an independent estimate of the inventories of 90Sr, 137Cs and 239,240Pu from two major contamination events in the South Urals, namely, the Kyshtym accident in 1957 and the Karachay wind dispersion in 1967. The calculations are based upon deposition measurements of the radionuclides carried out on soil samples assuming that the depositions decreased exponentially with distance from the two sources. The inventory estimates are compared with the available Russian information on the two accidents.

An approach to dose reconstruction for the Urals population.

Population exposure in the Urals region occurred due to the releases of radionuclides by the Mayak plutonium facility in the 1950's. The major sources of radioactive contamination were the discharges of liquid wastes into the Techa river (1949-1956); an explosion in the storage facility for high level radioactive wastes which formed the East Urals Radioactive Trace in 1957; and gaseous aerosol releases within the first decade of the facility's operation (1949-1957). The problems of dose reconstruction for the population exposed on the Techa river banks and East Urals Radioactive Trace are outlined. The initial data sets and basic models for dose reconstruction are described. The main tasks of the Techa River Dosimetry System Project and the approaches to individual internal and external dose reassessment are formulated.

Epidemiology of accidental radiation exposures.

Much of the information on the health effects of radiation exposure available to date comes from long-term studies of the atomic bombings in Hiroshima and Nagasaki. Accidental exposures, such as those resulting from the Chernobyl and Kyshtym accidents, have as yet provided little information concerning health effects of ionizing radiation. This paper will present the current state of our knowledge concerning radiation effects, review major large-scale accidental radiation exposures, and discuss information that could be obtained from studies of accidental exposures and the types of studies that are needed.

Serious Radiation Accidents and the Radiological Impact on Agriculture

The consumption of food products obtained in areas subjected to radioactive contamination as a consequence of a radiation accident appears to be the most significant source of irradiation for the population. At the same time, this route can be regulated very effectively. The regularities of contamination of agricultural production, peculiar features of internal dose formation in the population and the effectiveness of countermeasures in agriculture have been analysed using the experience of two major accidents in the former USSR - in the South Urals (Kyshtym accident) in 1957, and at the Chernobyl NPP in 1986.

Accumulation and distribution of long-living radionuclides in the forest ecosystems of the Kyshtym accident zone

The concentration of Strontium-90 and Cesium-137 in soil and woody plants was studied in the Sverdlovsk region of the zone contaminated as a result of the Kyshtym accident in the southern Urals in 1957. In the forest ecosystems under study, the total concentration of strontium-90 varied from 1.5 to 63.4 kBq/m 2 , while that of cesium-137 did not exceed 13 kBq/m 2 . Soil contamination resulted in an increase in the concentration of radionuclides in woody plants. Thus, the concentration of strontium-90 in different parts of birch samples was higher than in the controls by a factor of 5–16, while for pine, it was higher by a factor of 2–4.

Main investigation results on the forest radioecology in the Kyshtym and Chernobyl accident zones

As a result of the long-term studies of radionuclide migration in forest ecosystems in zones of radioactive contamination after the Kyshtym and Chernobyl accidents, the following trends were revealed: (1) High retention capacity of stand canopy with respect to radioactive fallout. This leads to high doses absorbed by apical and leaf meristems, β-radiation giving the main part of the dose; (2) Fast self-decontamination of crowns during the growth period and relatively slow decontamination in the phase of physiological rest, regardless of amount of atmospheric precipitation. The rate of crown decontamination determines the value and duration of radiation stress on woody plants; (3) Accumulation not less than 95% of the total radionuclide amount in the forest litter 1–2 years after the cessation of radioactive fallout; (4) Relatively slow migration of strontium and cesium radionuclides along the forest soil profile; (5) High capacity of the forest when serving as a biogeochemical barrier to the routes of horizontal and vertical radionuclide migration and export out of the zone of initial contamination, including migration into the river water; (6) Considerable difference between strontium and cesium when migrating in forest soils and in the soil-plant system; (7) Broad variations in transfer factors for uptake of cesium-137 from soil into forest plants depending on the plant species and soil type. The primary radiobiological effects connected with irradiation of organisms are considered and secondary disturbances due to changes of ecological bonds between the components of irradiated forest ecosystem are discussed.