This article provides an overview and comparison of software tools to predict the public radiation effect under normal and off-normal NPP operating conditions. The main characteristics, functional features, advantages and disadvantages of the software packages RESRAD, CROM, PC-CREAM 08®, ESTE Annual Impacts, РОМ, ESTE, NOSTRADAMUS, RECASS, RODOS were addressed. Criteria for assessing the quality and efficiency of software tools were highlighted. The optimal computational toolware applicable to the NPP normal (CROM package) and off-normal (RODOS system) operating conditions was substantiated.

The paper presents a comprehensive analysis of the IAEA's methodology for calculating the operational intervention levels (OILs) to protect the public in the aftermath of a radiation disaster based on monitoring data. Developing the OILs assessment approach involves outlining specific indicators based on accident scenario characteristics, geographical location of nuclear power plants, timing after releases, and dose criteria established by the Russian regulatory documents. The paper highlights the feasibility of using a unified computation tool to solve interconnected tasks, such as "prediction of radiological consequences" and "development of monitoring OILs". A methodological approach to assessing monitoring OILs using RODOS models, designed for predicting the consequences of a radiation accident, has been developed. This approach includes three stages: assessing the radiological significance of a scenario, evaluating monitoring OILs for different generic criteria, and justifying the recommended values of OILs. Calculations were performed to show how the new methodology can be used based on the data for the most severe possible accidents at VVER-440, VVER-1000, VVER-1200, and BN-800 reactors. The results showed that the maximum radiation doses for the prospective BN-800 and VVER-1200 reactors do not exceed the dose criteria for evacuation of the public. The dynamics of OILs were computed for the most severe accident scenario at the VVER-440 reactor, using the "ambient dose rate" metric and "evacuation" dose criteria for effective and thyroid exposure, which are justified in the Russian NRB-99/2009. The OILs obtained through the presented methodology have been compared to the aggregated values of the same indicator calculated using the IAEA methodology in a "ground scenario". Further research is needed to validate monitoring techniques for potential accidents at Russian nuclear power plants. The research should consider regional conditions and the Russian regulatory framework.

The methodical approach based on scenarios of design and beyond design basis accidents was developed for comparative radioecological assessment of reactor facilities. The dynamics of possible radiation doses to the thyroid and the whole body of the public resided nearby the Russian nuclear power plants equipped with the VVER-440, VVER-1000, VVER-1200 and BN-800 reactors was estimated. With the use of the conservative approach for each accident scenario, as well as with the use of acute and medium-term dose criteria, radiation exposure indices were calculated for each accident scenario. Reactor facilities are ranked according to an index summarizing the accident scenarios features and the probability of their realization, the height of radioactive emissions and the activity of dosage-forming radionuclides. The potential radioecological danger of Russian reactors to the population has been reduced. The lowest estimates of the summarized emergency risk are typical for the advanced VVER-1200 reactor of the 3+ generation and the fast neutron reactor BN-800. The most severe emergency scenarios for each considered reactor are highlighted. The VVER-440 reactor has the highest number of severe projected accidents exceeding the dosage criteria envisaging evacuation of the population. The directions of further research related to the analysis of the environmental radiological effects, the justification of radiation protection measures and the development of operational intervention levels in the acute post-accident period are outlined.

System analysis was conducted to examine the atmospheric emissions from Russian nuclear power plants with various types of reactors during normal operation, as well as the emissions for design and beyond-design accident scenarios. Through many years of study, the main radionuclides that contribute to the total activity were identified. The composition of emissions from postulated accidents at the boiling water reactor (BWR) and pressurized water reactor (PWR) has been analyzed. The obtained results are considered as initial data for calculating the dose load on the population from NPP releases and formation of lists of the main dose-forming radionuclides. The necessary components of such calculations are models parameterized on regional data. Ranking in the system “radionuclide – environmental component” is considered as an important stage for developing the Regulation for Environmental Monitoring of the NPP location area.

The partial radiation doses on the population from radionuclides contained in various environmental components due to gas aerosol releases of nuclear power facilities are estimated. Calculations were carried out for facilities with promising reactors of two different types, VVER-1200 and BREST-OD-300, in the complex with enterprises of the stationary nuclear fuel cycle. The CROM code recommended by the IAEA was used as an assessment tool. Ranking of partial radiation doses forming the total dose from atmospheric releases was made. It is shown that the controlled radionuclides in the list of Sanitary Rules for the Design and Operation of Nuclear Power Plants are not the main dose-forming radionuclides for the facilities under consideration. The Methodological Guidelines for the Organization of Radioecological Monitoring of Agroecosystems in the area of impact of radiation hazardous facilities also do not pay attention to radionuclides, which are significant in terms of dose formation. The results of the calculations presented in this article can be used in the development of radioecological monitoring programs aimed at assessing public exposure from atmospheric releases within compliance with dosimetric constraints (quotas) for the nuclear power facilities considered.

The paper presents a brief analysis of indicators designed to assess the radioecological situation in the acute period after a nuclear accident and to apply protective measures. Authors described an approach to the evaluation of operational intervention levels (OILs) for the protection of the members of the public recommended by the IAEA. The OILs for the indicators “ambient dose rate” and “concentration of I-131 and Cs-137” have been calculated based on the emergency scenarios for Russian NPPs. The input data included the information about the radioactive releases to the atmosphere due to design-based and beyond design-based accidents at NPPs with reactors VVER-1000, VVER-1200, RBMK-1000 and BN-800. The excess in the calculated "monitoring" operational intervention levels means the exceeding the dose criteria for protecting the public, which requires the implementation of protective measures. The generalization of the OILs calculated for each emergency scenario on a conservative basis resulted in an establishment of generalized (unified) OILs. The values of the latter differ from the values of similar indicators recommended by the IAEA, which is due to the specific nature of the radionuclide composition of releases from beyond design basis accidents at sodium-cooled BN-800 reactors. The paper shows the significance of the OILs established in the first period after the accident based on data on actual accidental releases using the appropriate calculation tools. The conclusion is that it is necessary to consider accident scenarios for all types of reactors when calculating generalized OILs for Russian NPPs.

Ведение агропроизводства в условиях широкомасштабного радиоактивного загрязнения сельскохозяйственных угодий и поиск эффективных путей снижения содержания радионуклидов в агропродукции требуют разработки и совершенствования методов радиоэкологического прогнозирования. В результате синтеза разработанных радиоэкологических моделей и параметрического обеспечения на языке B4A было создано мобильное приложение PlantCs, предназначенное для работы на устройствах с установленной операционной системой Android. Приложение PlantCs позволяет решать задачи, связанные с прогнозированием накопления 137Cs в продукции растениеводства и кормопроизводства, получаемых на радиоактивно загрязненных сельскохозяйственных угодьях. Эти задачи заключаются в прогнозировании рисков превышения норматива (РПН) содержания 137Cs в сельскохозяйственной продукции, оценки предельных уровней загрязнения угодий, обеспечивающих соблюдение заданных РПН и оценку времени автореабилитации территорий, по истечении которого достигаются допустимые РПН для продукции растениеводства и кормопроизводства.

Purpose: the development of statistical models for forecasting the accumulation of 137Cs in crop production, model parameterisation and prognostic estimates for the territories of the Bryansk region contaminated with 137Cs because of the Chernobyl accident. Material and methods: The use of a probabilistic approach for correct predictive assessments of the safety of agricultural products from radioactively contaminated agricultural lands has been substantiated. Analytical models were developed in the framework of a probabilistic approach to predict the risks of radioactive contamination of crop products, to assess the permissible levels of contamination of arable lands and the time of their natural remediation. Results: Based on a statistical analysis of radioecological survey data, it was established that the 137Cs contamination density of the soil follows a lognormal distribution law with a high level of significance. For farms in the south-western districts of the Bryansk region, it was shown that, if the average values of 137Cs content in crop production corresponded to the established standard, the risks of its excess could reach 30 %. This is due to the variability of 137Cs soil contamination densities and migration parameters. The dependences of limiting soil contamination densities of 137Cs on the risk of exceeding the standards (RES) of the content of this radionuclide in products were presented. The time of natural rehabilitation of arable agricultural land with a given risk for products of 10 % can exceed 30 years. Conclusion: The application of probabilistic methods to predict the consequences of 137Cs contamination of agricultural lands makes it possible to correct practical recommendations developed on the basis of a deterministic approach. The results of prognostic calculations are the basis for planning and evaluating the possibility of returning territories contaminated by 137Cs to economic use. The developed methodology and models can be used in the development of decision support systems for the remediation of agricultural lands exposed to radioactive fallout.

This paper presents a radioecological assessment of forage agricultural land in the southwestern districts of the Bryansk region based on data characterizing the variability of the radionuclides content in the soil. Concentration of 137Cs in forage was calculated taking into account the proba-bility distributions of 137Cs soil contamination density and the soil to plant transfer factor. The pro-cessing data of the radioecological survey has shown the soil contamination density with 137Cs of agricultural lands in the southwestern areas of the Bryansk region obeys a lognormal law. The authors have used statistical models and software modules for the radioecological assessment of forage lands. Risks of exceeding the 137Cs content standards in forage obtained on soils with different texture have been calculated. The limiting levels of contamination of pastures and hay-fields with 137Cs, ensuring compliance with the specified risks for forage, have been estimated. The lowest limiting soil contamination density is characteristic of organic soils, which can be con-sidered “critical” from the point of view of 137Cs intake into forage. The authors have predicted the time of remediation of forage lands in the southwestern districts of the Bryansk region in the ab-sence of protective measures based on a probabilistic approach. The time period during which the risk of forage contamination for sandy, sandy loam and clay loam soils will decrease to 10% varies for the areas under consideration in a wide range, not exceeding 64 years. It is concluded that it is advisable to substantiate the value of the acceptable risk of forage contamination, taking into account radiological and socio-economic aspects.

Evaluation of radiation impact on biota inhabiting near nuclear facilities of radioactive release to atmosphere from reactors of different types (WWER-1200, BN-600, BN-800, UVV-2M) is consid-ered in the paper. Radiation dose rates to reference groups of terrestrial biota species (annelids, insects, large and small mammals, grasses and conifers) vary from 0.01 to 0.2 µGy/day. The im-pact of the NPP using up-to-date reactor WWER-1200 is shown to be not exceeding 1% of the to-tal radiation impact. To compare correctly radiation impacts on the biota species from radioactive release and from exposure to established radiation dose rate limits, it is necessary to take into account contribution of all constituents of radiation background. Impacts on biota species from the total exposure to radioactive release or the exposure to established radiation dose rate limits were evaluated. Estimated radiation impact from exposure to the radioactive release did not ex-ceed 0.1; the impact from the established dose rate limits was 0.9. Obtained information allows making the following conclusion: uncertainty of quantitative evaluation of radiation impact on bio-ta in planned radiation situations is mainly caused by uncertainty of established dose rate limits. There is a need to establish dose criteria for emergency, it will allow creating “weighty” radioeco-logic justification of “nuclear power plants with account for potential emergency conditions.

Описана история развития применения методов математического моделирования во ВНИИРАЭ. Показана роль математического моделирования в решении научных и прикладных задач радиационной экологии. Приведены основные результаты исследований в области разработки и применения радиоэкологических моделей, программных средств и систем поддержки принятия решений во ВНИИРАЭ. The history of development of mathematical modeling methods application in RIRAE is described. The contribution of mathematical modeling in solving scientific and applied problems of radioecology is shown. The main results of research in the field of development and application of radioecological models, software tools and decision support systems in RIRAE are covered.

A prognosis is made of the radiation impact of planned atmospheric emissions and liquid discharges from NPP with VVER-1200 on native ecosystems. The ERICA assessment tool was used to assess the dose loads for ICRP-recommended representative organisms. The expected irradiation dose from NPP for representatives of the biota is compared with the dose from the existing irradiation, evaluated on the basis of radioecological inspection in the locale of power plants in Kaliningrad region. The dose loads on the biota are expected to be below the threshold levels of irradiation. Planned emissions and discharges from the NPP will not have an appreciable impact on the native ecosystems.

Abstract The article presents a long-term prediction of radiation doses to members of the public and reference organisms of biota from planned radioactive atmospheric releases by the Baltic nuclear power plant with VVER-1200. The calculation of atmospheric dispersion and radiation dose to the population have performed on the basis of general models presented in the IAEA Safety Report Series No. 19. The radiation doses to non-human biota have calculated using the ERICA Tool. Annual effective dose to the population near the Baltic NPP are expected to be below 2.1 μSv. The dose rate of reference organisms will not exceed 0.6 nGy/h. The main contribution to the irradiation of both population and non-human biota will be made by 14C and 3H. It has recommended to include these radionuclides in the radioecological monitoring program of natural and agricultural ecosystems in the area where the Baltic NPP is located.

The objective of this work is to develop an approach to evaluating the effect of the radiation factor on biota for radioecological comparison of scenarios of serious beyond-design basis accidents in NPP. The tree tier of a coniferous (pine) forest exposed to atmospheric precipitation and possessing high sensitivity to radiation is studied as a representative natural community. The indices of the radiation effect are the radioecological risks calculated taking account of the distribution of the dose load on the natural object. The risks of exceeding the lethal and semi-lethal radiation doses, as well as the area of the radioactive track for postulated scenarios of beyond-design basis accidents at BWR-1412, EPR-1600, and PWR-890 reactors, are evaluated. Based on the calculation, a radioecological ranking of the considered emergency scenarios was performed.

The dose loads from the natural and technogenic background to the population living in the vicinity of NPP with VVER-1200 in Kaliningrad Oblast were estimated on the basis of radioecological inspection data. The average yearly effective population irradiation dose from natural and technogenic radionuclides present in the environment is equal to 2.42 mSv. The population radiation impact from atmospheric emissions is predicted. The maximum dose load is ~1 μSv/yr and does not exceed the quota for radioactive emissions from NPP 10 μmSv/yr.

К вопросу об оптимизации радиоэкологического мониторинга в регионе размещения предприятий ядерного топливного циклаСпиридонов С.И

Obninsk Methodological approaches to the organization of state and departmental systems for environmental monitoring environment in order to ensure the radiation and ecological safety of population and biota in the vicinity of nuclear and radiation hazardous facilities (NF) are reviewed. The authors jus-tify the need for implementation of the monitoring at all stages of the facilities life cycle, tailored to the facilities features, regional-specific factors, as well as personnel, the public and biota exposure situations. The authors defined directions of radioecological monitoring of a facility (facility level), radiation-hygienic level (evaluation of exposure of the public, biota and ecosystems to released ra-dionuclides), socio-hygienic level, prospective (evaluation of health effects), agroecological, biologi-cal and ecological levels. The impact of the facilities operations on the public and biota is evaluated on the basis of data of the long-term surveillance of radionuclides concentration in the lowest atmospheric layer, terrestrial (agro- and natural) and aquatic ecosystems. Various aspects of radia-tion-ecological monitoring, strengths and shortcomings of used methods are reviewed. Analysis of the current organization system of radioecological monitoring allows making the following conclu-sions: efficiency and organization of radioecological monitoring need to be enhanced and opti-mized. The comprehensive radioecological monitoring integrated elements of different systems of the monitoring due to interaction of different agencies should be developed. Implementation of integrated radioecological monitoring on areas of NF location should be based on integrated risk values for population and biota from wide range sources of pollution considering migration pathways of toxicants in critical