Environmental behaviour of radioactive particles: Transfer to animals.

Field data on behaviour of artificial polydisperse radioactive silica particles in the components of the cattle food chain are presented. The model fused radioactive particles reproduced the spherical shape of particles in the local deposition during nuclear tests, including their specific gravity and polydispersity. It is shown that the composition of radioactive particles entering the body of animals differs from those initially deposited on the surface of pasture grass. The intake of particles into the body of animals decreased with increasing particle size. The intake for particles of 400-800 µm was about 10 times lower than that for fine particles sized 0-100 µm. It was found that the excretion rate of radioactive particles from the animal body also depends on particle size. The deposition of radioactive particles on the fundal surface of the wall of the ventral rumen sac and reticulum, as well as the long-term retention of radioactive particles of all sizes in the abomasum was noted. This can result in substantial damage in the GIT system, in particular, in these parts of the cattle digestive tract the focal ulcerative lesions of the mucous membrane can be formed by « hot ¼ radioactive particles.

Review of Russian research with radioactive particles: Foliar uptake.

Studies performed in the former Soviet Union were reviewed to provide interception and weathering values for radioactive particles. None of these studies were available in the English language literature before or were considered in the international reviews. The estimated mass interception fractions ranged 0.2-1.4 m2 kg-1 may be explained by the size of the particles used in the research. The interrelationships among the interception fractions, plants biomass and size of radioactive particles were determined for different plants: spring and winter wheat, maize, rice, pasture and sown grass. A filtration model rather accurately approximated data for pasture grass and some other crops but does not reflect properly patterns of the interception fraction dependence on biomass for perennial sown grass. The values derived have been compared with some expected values reported by the IAEA's Handbook of parameter values for the prediction of radionuclide transfer in temperate environments (TRS 472) where possible. The information presented can be used in the current updating of parameters recommended for environmental impact assessments.

Review of Russian language studies on radionuclide behaviour in agricultural animals: Transfer to animal tissues.

Data on radionuclide transfer to animals from research performed in the former Soviet Union were reviewed to collate transfer coefficient values (Ff) to animal tissues such as liver, kidney and bone, but not muscle which has previously been reported. The derived values were compared with selected data published in the English language literature. The new data are mainly for 90Sr and 137Cs, although some data were also provided for 3H, 54Mn, 59Fe, 60Co, 22Na 65Zn, 131I and U. The Russian language data may provide a basis for better informed evaluation of radiation dose from the consumption of such animal products, which can form important components of the diet in some countries.

[Methodological Approaches to the Organization of Counter Measures Taking into Account Landscape Features of Radioactively Contaminated Territories].

Methodological approaches to the organization of counter measures are considered taking into account the landscape features of the radioactively contaminated territories. The current status and new requirements to the organization of counter measures in the contaminated agricultural areas are analyzed. The basic principles, objectives and problems of the formation of counter measures with regard to the landscape characteristics of the territory are presented; also substantiated are the organization and optimization of the counter measures in radioactively contaminated agricultural landscapes.

[Radiological Aspects of Transition of Russian Areas Affected by the Chernobyl Accident to Normal Activities].

Dynamics of radiation situation in settlements, agriculture and forestry on the Russian Federation areas af- fected by the Chernobyl accident is presented. A set of challenging problems on public radiation protection and rehabilitation of territories was determined. The main objective at a long-term period after the accident is a stage-wise return of the affected areas to normal activity without any radiological criteria restrictions. For practical realization of this process it is necessary to change the national statutes and regulations consid- ering the contemporary international approaches, to pass to the current exposure situation and to establish reference levels, to define criteria of transition of the areas affected after the Chernobyl accident to normal activity. The change of conceptual approaches will allow one to revise the boundaries of settlement zoning and to develop the regulatory framework on procedures of changing their status from radioactively contami- nated zone to normal activity zone; to develop the regulatory framework on the procedures of transition of agricultural and forest lands classified as radioactively contaminated zones to territories where the traditional husbandry is possible. The Russian Federation has positive experience of transition of areas contaminated as a result of the Chernobyl accident to normal activity.

Review of Russian language studies on radionuclide behaviour in agricultural animals: biological half-lives.

Extensive studies on transfer of radionuclides to animals were carried out in the USSR from the 1950s. Few of these studies were published in the international refereed literature or taken into account in international reviews. This paper continues a series of reviews of Russian language literature on radionuclide transfer to animals, providing information on biological half-lives of radionuclides in various animal tissues. The data are compared, where possible, with those reported in other countries. The data are normally quantified using a single or double exponential accounting for different proportions of the loss. For some products, such as milk, biological half-lives tend to be rapid at 1-3 d for most radionuclides and largely described by a single exponential. However, for other animal products biological half-lives can vary widely as they are influenced by many factors such as the age and size of the animal. Experimental protocols, such as the duration of the study, radionuclide administration and/or sample collection protocol also influence the value of biological half-lives estimated.

[Future development of radioecological investigations--new international projects].

Information is given on the future development of nuclear power engineering and the need to ensure environmental safety. The complexity of the emerging problems requires a wide international integration of scientific investigations. Also described are ecological projects that have been implemented by the IAER after the Chernobyl NPP accident, as well as a new project, MODARIA, which will pay special attention to the improvement of models for radionuclide transfer and estimation of radiation effects on both humans and biota. The strategy and agenda for the development of radioecological studies in the 21st century are described which are being realized by the nine key research centers (European Radioecology Alliance) under the EC project STAR.

Justification of remediation strategies in the long term after the Chernobyl accident.

Following the accident at the nuclear power plant in Chernobyl a number of different remedial actions were developed and implemented in Belarus, Russia, and Ukraine. Recommendations on the application of countermeasures and remedial actions were published by the IAEA as "Guidelines for agricultural countermeasures following an accidental release of radionuclides" in 1994. Since then, new information on the behaviour of radionuclides in the environment and effectiveness of countermeasures in the long term has been obtained and reviewed by many projects, including the Chernobyl Forum. Additionally, new approaches to derive remediation strategies were developed and successfully implemented in the most affected countries. This paper describes a justification of the remediation strategies suggested for rehabilitation of the areas most affected by the Chernobyl accident based on this experience.

Radionuclide transfer to freshwater biota species: review of Russian language studies.

Around 130 publications reporting studies on radionuclide transfer to freshwater biota species conducted in the former USSR were reviewed to provide the concentration ratio values. None of these studies were available up to now in the English language reviews or publications. The values derived have been compared with the CR values used for freshwater systems in the International reviews. For some radionuclides reviewed in this paper, the data are in good agreement with the mean CR values presented earlier, however for some of them, in particular, for ²4¹Am (bivalve molluscs, gastropods and pelagic fish), 6°Co (gastropods, benthic fish and insect larvae), 9°Sr and ¹³7Cs (benthic fish and zooplankton), the mean values given here are substantially different from those presented earlier. The data reported in this paper for thirty five radionuclides and eleven groups of freshwater species markedly improve the extent of available data for evaluation of radiation impact on freshwater species.

ReSCA: decision support tool for remediation planning after the Chernobyl accident.

Radioactive contamination of the environment following the Chernobyl accident still provide a substantial impact on the population of affected territories in Belarus, Russia, and Ukraine. Reduction of population exposure can be achieved by performing remediation activities in these areas. Resulting from the IAEA Technical Co-operation Projects with these countries, the program ReSCA (Remediation Strategies after the Chernobyl Accident) has been developed to provide assistance to decision makers and to facilitate a selection of an optimized remediation strategy in rural settlements. The paper provides in-depth description of the program, its algorithm, and structure.

Radionuclide transfer to marine biota species: review of Russian language studies.

An extensive programme of experiments on transfer of radionuclides to aquatic species was conducted in the former USSR starting from the early 1950s. Only a few of these studies were made available in the English language literature or taken into account in international reviews of radionuclide behaviour in marine ecosystems. Therefore, an overview of original information on radionuclide transfer to marine biota species available from Russian language literature sources is presented here. The concentration ratio (CR) values for many radionuclides and for marine species such as: (239)Pu, (106)Ru and (95)Zr (crustacean), (54)Mn, (90)Sr, (95)Nb, (106)Ru, (137)Cs (239)Pu, (241)Am and natural U (molluscs), and (54)Mn, (90)Sr, (137)Cs and (144)Ce (fish) are in good agreement with those previously published, whilst for some of them, in particular, for (32)P and (110)Ag (crustaceans), (35)S (molluscs), (32)P, (35)S, (95)Nb, and (106)Ru (macroalgae) and (60)Co and (239,240)Pu (fish) the data presented here suggest that changes in the default CR reference values presented in recent marine reviews may be required. The data presented here are intended to supplement substantially the CR values being collated within the handbook on Wildlife Transfer Coefficients, coordinated under the IAEA EMRAS II programme.

Rural areas affected by the Chernobyl accident: radiation exposure and remediation strategies.

Main objectives of the present work were to develop an internationally agreed methodology for deriving optimized remediation strategies in rural areas that are still affected by the Chernobyl accident, and to give an overview of the radiological situation in the three affected countries, Belarus, Russia and Ukraine. Study settlements were defined by having in 2004 less than 10,000 inhabitants and official dose estimates exceeding 1 mSv. Data on population, current farming practices, contamination of soils and foodstuffs, and remedial actions previously applied were collected for each of such 541 study settlements. Calculations of the annual effective dose from internal radiation were validated with extensive data sets on whole body counter measurements. According to our calculations for 2004, in 290 of the study settlements the effective dose exceeded 1 mSv, and the collective dose in these settlements amounted to about 66 person-Sv. Six remedial actions were considered: radical improvement of grassland, application of ferrocyn to cows, feeding pigs with uncontaminated fodder before slaughter, application of mineral fertilizers for potato fields, information campaign on contaminated forest produce, and replacement of contaminated soil in populated areas by uncontaminated soil. Side effects of the remedial actions were quantified by a 'degree of acceptability'. Results are presented for two remediation strategies, namely, Strategy 1, in which the degree of acceptability was given a priority, and Remediation Strategy 2, in which remedial actions were chosen according to lowest costs per averted dose only. Results are highly country-specific varying from preference for soil replacement in populated areas in Belarus to preference for application of ferrocyn to cows in Ukraine. Remedial actions in 2010 can avert a large collective dose of about 150 person-Sv (including averted doses, which would be received in the following years). Nevertheless, the number of inhabitants in Belarusian and Russian settlements with annual doses exceeding 1 mSv remains large. Compared to international values for the cost-effectiveness of actions to reduce occupational exposures, the recommended remediation strategies for rural areas affected by the Chernobyl accident are quite cost-effective (about 20 keuro/person-Sv).

[Revision of parameters of radionuclide migration in agroecosystems].

Results of the project IAEA "Environmental Modelling for Radiation Safety" (EMRAS) on revision of parameters of radionuclide migration in agroecosystems are presented. Methodical approaches to a grouping of the initial information are stated. The databases on parameters of radionuclide transfer in agricultural plants for various climatic zones, and also in system a diet--an organism of an agricultural animal are described. The examples of an estimation of parameters are resulted.

[Horizontal and vertical migration of 137Cs on slopes landscapes].

The paper considers the results of field researches on studying the basic laws of 137Cs migration on slopes landscapes. The characteristic of horizontal and of vertical 137Cs migration is given depending on an element of a relief, geomorphological conditions and properties of soil. Critical kinds of slopes with the most intensive streams of radionuclides migration and the maximal accumulation of 137Cs in plants have been determined.

Review of Russian-language studies on radionuclide behaviour in agricultural animals: part 4. Transfer to poultry.

Data on radionuclide transfer to domestic chickens and ducks obtained from research performed in the former Soviet Union were reviewed to provide transfer coefficient values (Ff) to poultry and edible egg contents. The majority of the data are from experiments with (90)Sr and (137)Cs, reflecting the importance of these radionuclides after global fallout and major radiation accidents. Data for (3)H, (54)Mn, (59)Fe, (60)Co, (22)Na (65)Zn, (131)I and U are also given. The values derived have been compared with those in the current IAEA Handbook of parameter values for the prediction of radionuclide transfer in temperate environments (TRS 364) and the recent revision which incorporates the values from this paper. The Russian-language data give improved estimates for many radionuclides and the revised handbook is now based on the better quality data given for chronic administration.

Review of Russian language studies on radionuclide behaviour in agricultural animals: 3. Transfer to muscle.

Over 150 publications reporting studies conducted in the former USSR were reviewed to provide transfer coefficients (F(f)) to the muscle of domestic animals from experiments using chronic administration, often for long timescales in large scale experiments. Only a few of these studies were made available in the English language literature or taken into account in international reviews. The values derived have been compared with expected values reported by the IAEA's Handbook of parameter values for the prediction of radionuclide transfer in temperate environments (TRS 364) where possible. The information presented here has been used in the current updating of parameters recommended for environmental assessments by the IAEA. Many of the reported values are for Sr due to the Mayak accident and Cs due to the Chernobyl accident. Nevertheless, the reported data for a wide range of radionuclides, in particular for Ru, Sb, and Zn markedly improve the extent of available data.

Proposal for new best estimates of the soil-to-plant transfer factor of U, Th, Ra, Pb and Po.

There is increasing interest in radiological assessment of discharges of naturally occurring radionuclides into the terrestrial environment. Such assessments require parameter values for the pathways considered in predictive models. An important pathway for human exposure is via ingestion of food crops and animal products. One of the key parameters in environmental assessment is therefore the soil-to-plant transfer factor to food and fodder crops. The objective of this study was to compile data, based on an extensive literature survey, concerning soil-to-plant transfer factors for uranium, thorium, radium, lead, and polonium. Transfer factor estimates were presented for major crop groups (Cereals, Leafy vegetables, Non-leafy vegetables, Root crops, Tubers, Fruits, Herbs, Pastures/grasses, Fodder), and also for some compartments within crop groups. Transfer factors were also calculated per soil group, as defined by their texture and organic matter content (Sand, Loam, Clay and Organic), and evaluation of transfer factors' dependency on specific soil characteristics was performed following regression analysis. The derived estimates were compared with estimates currently in use.

Chernobyl radionuclide distribution, migration, and environmental and agricultural impacts.

The distribution and migration of radionuclides released into the environment following the Chernobyl accident in 1986 are described. The Chernobyl disaster resulted in the consumption of farm products containing radionuclides as a source of irradiation of the population due to the prevalence of a rural type of human nutrition in the affected region. Economic and radiologic importance of countermeasures for reducing the impacts of the accident are described. The basic radioecological problem is described in which the area where direct radiation contamination of biota was observed is considerably smaller than the zone where concentrations of radionuclides through the food chain exceeded the permissible standards. The radiation-induced effects in biota in the affected area are described. In the long-term post-accident period, the radionuclide distribution between components of ecosystems (including humans) and doses are considered in comparison to a technologically normal situation of nuclear power plant operation. This analysis demonstrates that if radiation standards protect humans, then biota are also adequately protected against ionizing radiation.

[The radioecological situation in the agricultural sphere in the contaminated regions of russia during the long-term after the Chernobyl accident].

The results of the contamination monitoring of the agricultural land and products in 2000-2005 in the regions of Russia affected by the Chernobyl accident are presented. The contribution is assessed of foodstuffs to the formation of internal exposure doses to the population during the long-term after the accident. Prediction is made of the change in the radioecological situation in radioactively contaminated areas.

Review of Russian language studies on radionuclide behaviour in agricultural animals: part 2. Transfer to milk.

An overview of original information available from Russian language papers on radionuclide transfer to milk is provided. Most of the data presented have not been taken into account in international reviews. The transfer coefficient (F(m)) values for radioactive isotopes of strontium, caesium and iodine are in good agreement with those previously published. The Russian language data, often based on experiments with many animals, constitute a considerable increase to the available data for many less well-studied radionuclides. In some instances, the Russian language data suggest changes in recommended values (e.g. Zr and Ru). The information presented here substantially increases the amount of available data on radionuclide transfer to milk and will be included in the current revision of the IAEA TRS Handbook of parameter values for radionuclide transfer.