[en] Lessons learned from the emergency response and recovery operations undertaken after the major nuclear accidents at Chernobyl NPP and at Fukushima Daiichi NPP are discussed. General information concerning radiation situation on-site is considered as the starting point for comparison of the applied actions and strategies. The similarity in emergency regulation and distinction in management are demonstrated. Comparison of average doses and dose distribution for different cohorts of emergency workers and recovery operation workers differ approximately by a factor of 10.

[en] The goal of this work is to evaluate different options of intervention for the recovery of contaminated environments. It will consider not only the efficiency of the countermeasures in terms of dose reduction, but also in terms of costs, wastes and other possible secondary consequences, in order to obtain the best possible strategy for each particular circumstance. This paper summarizes the methodology of optimization of intervention, which has been carried out in the framework of CEC-CHECIR ECP-4 Project

[en] The worked implemented within the framework of the project was directed towards understanding the conceptual basis for the organization of intervention strategies after the accident at the Chernobyl nuclear station. Based on the situation in regions of Belarus, Russia and Ukraine that suffered the consequences of the accident, this project was directed towards the provision of support the decision makers. The work will assist in the choice of proper strategies to protect the population from the effects of environmental contamination, taking into account the available resources. The experience gained, both of the problems of decision aiding in this context and their solution, will be of use in post-emergency planning for possible future accident situations. At present there are several prototype computer systems which provide the following: access to a wide range of information gathered after the accident at the Chernobyl nuclear station in the CIS; support in complex evaluations of the post-accident situation for a wide range of parameters; analysis and forecast of how the situation may develop using mathematical models and algorithms; support in choosing strategies at each level of decision making taking into account the possibilities of applying a wide range of countermeasures; exploration of multifactor interdependence and the consequences of resource and other limits; the integration of experience in social and psychological factors into the decision making process. Calculations made by the computer modules are based on actual data from contaminated territories including structure of soils, age/sex structure of the population, and dietary habits. At present the models for the calculation of doses and radionuclide migration in soil are specific to the regions contaminated after the Chernobyl accident. They m based on a large amount of experimental data ranging from whole body measurements of the population to data about radionuclide transfer from soils to plants, milk, and meat. A risk module has been developed which includes a database d demographic data on health protection for different territories, and which can calculate risk for any population structure. It can be used for risk estimation for different age groups in any region for which data is provided. A module on indirect countermeasures has been developed to assist in the selection of counter-measures that will improve conditions for a population that inhabits a contaminated area, in a way that is distinct from a direct reduction in the effective contamination level of the environment and its products. These types of countermeasure can be taken both as separate actions or in combination with direct countermeasures to increase the efficiency of the latter. The tools and interfaces developed within JSP2 enable the decision maker to estimate consequences and analyze the post-emergency situation according to his own criteria and in a user-friendly manner. The available analyses include: forecast calculations (concerning the estimated contamination of agricultural products, the levels of doses in the local population and the associated radiation risks); the identification of the critical factors that influence the health nf the affected population; a simulation of human intervention taking into account the countermeasures chosen or a time ordered set of countermeasures; an estimation of the influence such factors as dose, risk, cost/benefit and time, etc. have on decisions. The results can be presented in the form of maps, diagrams, and tables. In this paper, work carried out on the development of computer based decision support systems for the post-emergency management of contaminated territories is discussed, together with possibilities for further development of such systems

[en] The Chernobyl accident that occurred in Ukraine in April 1986 happened during an experimental test of the electrical control system as the reactor was being shut down for routine maintenance. The operators, in violation of safety regulations, had switched off important control systems and allowed the reactor to reach unstable, low-power conditions. A sudden power surge caused a steam explosion that ruptured the reactor vessel and allowed further violent fuel-steam interactions that destroyed the reactor and the reactor building. The Chernobyl accident was the most serious to have ever occurred in the nuclear power industry. The accident caused the early death of 30 power plant employees and fire fighters and resulted in widespread radioactive contamination in areas of Belarus, the Russian Federation, and Ukraine inhabited by several million people. Radionuclides released from the reactor that caused exposure of individuals were mainly iodine-131, caesium-134 and caesium-137. Iodine-131 has a short radioactive half-life (8 days), but it can be transferred relatively rapidly through milk and leafy vegetables to humans. Iodine becomes localized in the thyroid gland. For reasons of intake of these foods, size of thyroid gland and metabolism, the thyroid doses are usually greater to infants and children than to adults. The isotopes of caesium have relatively long half-lives (caesium-134: 2 years; caesium-137: 30 years). These radionuclides cause long-term exposures through the ingestion pathway and from external exposure to these radionuclides deposited on the ground. In addition to radiation exposure, the accident caused long-term changes in the lives of people living in the contaminated regions, since measures intended to limit radiation doses included resettlements, changes in food supplies, and restrictions in activities of individuals and families. These changes were accompanied by major economic, social and political changes in the affected countries resulting from the disintegration of the former Soviet Union. The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) has given particular attention to the accident. Estimates of average doses in separate regions of countries and for the population of the northern hemisphere as a whole were presented in Annex D of the UNSCEAR 1988 Report. The experience gained in treating the immediate radiation injuries of workers and fire fighters involved in controlling the accident were also reviewed in the UNSCEAR 1988 Report (Annex G). The UNSCEAR Committee is currently involved in the final phase of preparation of a further assessment of the exposures and effects of the accident. During the last several years, considerable attention has been devoted to investigating possible associations between health effects in the populations and the exposure to radionuclides released and dispersed following the Chernobyl accident. Of particular note has been the occurrence of numerous thyroid cancers in children. The number of thyroid cancers in individuals exposed in childhood, particularly in the severely contaminated areas of Belarus, Russia, and Ukraine is considerably greater than expected based on previous knowledge. The high incidence and the short induction period have not been experienced in other populations, and other factors are most certainly influencing the risk. If the current trend continues, further thyroid cancers can be expected to occur, especially in those exposed at young ages. The most recent findings indicate that the thyroid cancer risk for those older than 10 years of age at the time of the accident is leveling off, while the increase continues for those younger than 4-5 years in 1986. Apart from the dramatic increase in thyroid cancer after childhood exposure, there is no evidence of a major public health impact 14 years after the Chernobyl accident. No increases in overall cancer incidence or mortality have been observed that could be attributed to ionizing radiation. Risk of leukaemia, one of the major concerns after radiation exposure, does not appear to be elevated even among the recovery workers. Neither is there any scientific proof of other non-malignant disorders, somatic or mental, that are related to ionizing radiation. A majority of the epidemiological studies completed to date are of the descriptive type, in which average population exposures are correlated with the average rates of cancer incidence in specific time periods. As long as individual doses with reasonably low uncertainties are not available, the extent to which health effects might be radiation-related remains unclear. The reconstruction of individual doses is a key element in future research on radiation associated cancers related to the Chernobyl accident. Although the Chernobyl accident could shed some light on the knowledge on the late effects of protracted radiation exposures, it must be recognized that because of the relatively low doses received by the majority of exposed individuals, any increase in cancer incidence or mortality will be difficult to detect in epidemiological studies. (author)

[en] The initial registration brought to light the characteristics and disposition of wastes that should be disposed of on-site (special radioactive wastes). The criteria for validating the classification of radwastes as special are presented. The established criteria for the origin of wastes and the location of an object and its sanitaryprotective zone do not permit classifying the radwastes of certain large objects as special even though their removal is unjustified both in terms of dose loads and the risk of potential radiation as well as in terms of financial cost. Criteria are proposed for storage sites for special radwastes for inclusion in the developed regulatory documents, regulating their safe operation and transfer to accommodation and storage sites.

[en] Regulatory cooperation between the Norwegian Radiation Protection Authority and the Federal Medical Biological Agency (FMBA) of the Russian Federation has the overall goal of promoting improvements in radiation protection in Northwest Russia. One of the projects in this programme has the objectives to review and improve the existing medical emergency preparedness capabilities at the sites for temporary storage of spent nuclear fuel and radioactive waste. These are operated by SevRAO at Andreeva Bay and in Gremikha village on the Kola Peninsula. The work is also intended to provide a better basis for regulation of emergency response and medical emergency preparedness at similar facilities elsewhere in Russia. The purpose of this paper is to present the main results of that project, implemented by the Burnasyan Federal Medical Biophysical Centre. The first task was an analysis of the regulatory requirements and the current state of preparedness for medical emergency response at the SevRAO facilities. Although Russian regulatory documents are mostly consistent with international recommendations, some distinctions lead to numerical differences in operational intervention criteria under otherwise similar conditions. Radiological threats relating to possible accidents, and related gaps in the regulation of SevRAO facilities, were also identified. As part of the project, a special exercise on emergency medical response on-site at Andreeva Bay was prepared and carried out, and recommendations were proposed after the exercise. Following fruitful dialogue among regulators, designers and operators, special regulatory guidance has been issued by FMBA to account for the specific and unusual features of the SevRAO facilities. Detailed sections relate to the prevention of accidents, and emergency preparedness and response, supplementing the basic Russian regulatory requirements. Overall it is concluded that (a) the provision of medical and sanitary components of emergency response at SevRAO facilities is a priority task within the general system of emergency preparedness; (b) there is an effective and improving interaction between SevRAO and the local medical institutions of FMBA and other territorial medical units; (c) the infrastructure of emergency response at SevRAO facilities has been created and operates within the framework of Russian legal and normative requirements. Further proposals have been made aimed at increasing the effectiveness of the available system of emergency preparedness and response, and to promote interagency cooperation.

[en] Experience on restoration of contaminated areas in the past ten years reveals a specific problem in the general problem of solid radioactive waste management as a result of decontamination of the settlements. That specific problem concerns conventionally radioactive waste (CRW), which might be to some extent dangerous for human being. In the documents of IAEA and ICRP the approaches aimed at exemption or exclusion insignificant amount of radioactive wastes from regulatory control are actively being developed. In turn, Russia does not have so far either methodic or regulatory documents on management of very low level radioactive waste. Two approaches are considered in the paper under development of derived levels for CRW in case of restoration of contaminated areas. The first one is based on restriction of individual risk at level about 10^-6 per year (negligible level). The second one accounts for global man-made background and uses acceptable factor of excess of that background as a criterion.Under the first approach (restriction of individual risk) the lowest boundary of CRW is estimated to be equal to 3 Bq kg^-1 for ²³⁹Pu; 30 Bq kg^-1 for ⁹⁰Sr; and 300 Bq kg^-1 for ¹³⁷Cs, respectively. Those levels of specific activity approximately correspond to the areas contaminated by the above mentioned radionuclides 0.3 kBq m^-2, 3 kBq m^-2, and 30 kBq m^-2, respectively. Under the second approach if one accepts factor of 3 of excess of global man-made background, than the levels of specific activity will be 0.05 kBq m^-2 for ²³⁹Pu; 2.5 kBq m^-2 for ⁹⁰Sr, and 7.2 kBq m^-2 for ¹³⁷Cs. Comparison of the levels obtained according to the second approach shows that they will be several times lower than that according to the first approach. (author)

[en] In the 1960s two technical bases for the Northern Fleet were created in the Russian northwest at Andreeva Bay in the Kola Peninsula and Gremikha village on the coast of the Barents Sea. They maintained nuclear submarines, receiving and storing radioactive waste and spent nuclear fuel. No further waste was received after 1985, and the technical bases have since been re-categorised as temporary storage sites. The handling of these materials to put them into a safe condition is especially hazardous because of their degraded state. This paper describes regulatory activities which have been carried out to support the supervision of radiological protection during recovery of waste and spent fuel, and to support regulatory decisions on overall site remediation. The work described includes: an assessment of the radiation situation on-site; the development of necessary additional regulatory rules and standards for radiation protection assurance for workers and the public during remediation; and the completion of an initial threat assessment to identify regulatory priorities. Detailed consideration of measures for the control of radiation exposure of workers and radiation exposure of the public during and after operations and emergency preparedness and response are complete and provided in sister papers. The continuing requirements for regulatory activities relevant to the development and implementation of on-going and future remediation activities are also outlined. The Norwegian Radiation Protection Authority supports the work, as part of the Norwegian Government's plan of action to promote improvements in radiation protection and nuclear safety in northwest Russia.

[en] This paper looks at the key issues that need to be addressed during the transition from the emergency phase to the late phase of a radioactive release, and the development of the initial late phase strategy. It discusses the extent to which current national plans and international advice address the needs of decision makers following contamination of inhabited areas and food production systems. Based on this the following recommendations are made: (1) the issues that will arise at the start of the late phase response to a radioactive release require preparation work in advance of any release; (2) this preparation should consider the adequacy of legislation, technical data and modelling, options for waste storage and disposal, resources for monitoring and implementing clean up; (3) late phase preparedness requires regular exercising and (4) the possibility of terrorist releases adds further emphasis to the need for preparedness for the late phase. (authors)