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Small modular reactors represent a promising technology for power generation, offering solutions to the energy crisis and mitigating greenhouse gas emissions. As Ukraine considers the deployment of NuScale, UK SMR, and SMR-160, it is crucial to address the safe management of spent nuclear fuel. This study focuses on evaluating the radiological characteristics of spent nuclear fuel from the selected small modular reactors and for comparison, from the VVER-1000 reactor. Using the Monte Carlo code Serpent, depletion calculations were performed for an assembly in an infinite 2-D geometry, and the activity, decay heat, and inhalation toxicity of the spent nuclear fuel were assessed. We determined the main nuclides contributing to the radiological characteristics and quantified the mass content of these nuclides. The total number of spent nuclear fuel assemblies produced during the entire life of each small modular reactor type was estimated. The radiological characteristics assessed for the three small modular reactors do not exceed those observed for WER-1000 reactors currently operating in Ukraine. So, spent nuclear fuel generated by the selected small modular reactors will introduce no new challenges to Ukraine's radioactive waste management system. The results of this work provide valuable insights for identifying the optimal small modular reactor technologies for Ukraine concerning safe spent nuclear fuel management. [ABSTRACT FROM AUTHOR]

The results of the analysis of the radiation state of environmental objects in the sanitary protection zone (SPZ) and surveillance zone (SZ) of the research nuclear reactor (RNR) WWR-M of the Institute for Nuclear Research of the National Academy of Sciences of Ukraine (INR) for 2021 are analyzed and compared with the data for previous years (from 2016 to 2020). The levels of total beta activity of sedimentary dust and atmospheric precipitation and wastewater from the main reservoirs of INR, the concentration of beta-active aerosols in the surface layer of atmospheric air, as well as the content of 137Cs radionuclide in soil and vegetation samples, were studied. The research was conducted in the laboratory of the Center for Ecological Problems of Atomic Energy of INR. The obtained results show that in 2021 there was no excess of the values of controlled parameters compared to previous years. There was also no significant difference in the specific activity of the radionuclide 137Cs in soil and vegetation samples from SPZ and ZS. Studies conducted in the period from 2016 to 2021, allowed to accumulate significant factual material on the radiation situation in the sanitary protection zone and surveillance zone and to substantiate the conclusion about the absence of man-made radioactive contamination of the environment due to the operation of RNR WWR-M of INR of NAS of Ukraine. [ABSTRACT FROM AUTHOR]

In the first months of 2022, there was a sharp turn in the energy policy of the European Union, initially spurred by increasing energy prices and further escalated by Russia's invasion of the Ukraine. Further transformation of the energy system will likely be accompanied by the gradual abandonment of natural gas from Russia and an increase of renewable and nuclear energy. Such a transition will not only increase energy security, but also accelerate the pace at which greenhouse gas emissions are reduced in Europe. This could be achieved more effectively if some of the new nuclear energy capacity is optimized to play an increased balancing role in the energy system, thus allowing for deeper market penetration of intermittent renewable energy sources with a reduced need for flexible fossil backup power and storage. A double effect of decarbonization can be achieved by investments in nuclear repowering of coal-fired units, with the replacement of coal boiler islands with nuclear reactor systems. Repowered plants, in turn, operate flexibly via integration with thermal energy storage systems using molten salt. This paper presents the results of a technoeconomic analysis for three cases of nuclear repowering of a 460 MW supercritical coal-fired unit in Poland. The first reference case assumes that three reactors are replacing the existing coal boilers, while the second reference leverages two reactors. The third uses two nuclear reactors equipped with a molten salt thermal energy storage system as a buffer for the heat produced by the reactor system. The analysis of the third case demonstrates how the TES system's capacity varies from 200 to 1200 MWh, highlighting the possibility of obtaining a high degree of flexibility of the nuclear unit due to TES system without significant drops in the efficiency of electricity production. The economic analysis demonstrates that integration with TES systems may be beneficial if the current levels of daily variation in electricity prices are maintained. For current market conditions, the most attractive investment is a case with two reactors and a TES system capacity of 800 MWh; however, with the increasing price volatility, this grows to a larger capacity of 1000 or 1200 MWh. [ABSTRACT FROM AUTHOR]

In 1986, at the Chornobyl Nuclear Power Plant in the Exclusion Zone after an industrial accident, ecosystems began to have several features that distinguish them from the objects of the natural reserve fund. Parasitic systems are an informative indicator of the state of the ecosystem, which is now sporadically applied in the Exclusion Zone. Any change in the parasite population can lead to changes in the host population. The degree of imbalance in the "parasite-host" system depends on the strength and nature of the influence of external factors. At the same time, the presence of mutual adaptations of parasitic organisms and snails gives grounds to consider the "parasitehost" system comprehensively. Freshwater gastropod snails of various systematic groups, which can be intermediate and secondary hosts for trematode agents, were selected as an object of the study. In order to study freshwater gastropod snails for the presence of larval stages of helminths, snails were collected from such locations as Krasne Lake, Ilya River, Chernobyl Nuclear Power Plant cooling pond, bypass channel of the Chernobyl Nuclear Power Plant cooling pond, left bank of the Prypiat floodplain, Koshevka oxbow lake, Hrubchanskyi canal in the Meshevo village. Based on the results of the research, the presence of larval stages of trematode agents at different stages of their development (redia and metacercaria) parasitizing in the freshwater snails Lymnae stagnalis and Radix auricularia was established. [ABSTRACT FROM AUTHOR]

The results of implementing equipment qualification are analyzed. Such equipment is critical for the nuclear and technical safety of domestic nuclear power plants that are especially important for the implementation of the Program for extending the terms of out-of-project operation of power reactors that are capable of being used as powerful sources of electricity. Based on the comparison of published reliability indicators of domestic nuclear power plants before and after implementing the qualification, it is shown that still there are problems to be solved. The perspective of further enhancing the reliability of the operation of domestic nuclear energetics is considered, by implementing radiation functional testing methods that are been developed at the INR NAS of Ukraine for a long period. The basis of this method is detailed research and operational control of all processes that occur in critical equipment in any operating modes of nuclear reactors to form a resource history of the equipment and to provide operational information about the remaining resource and the expected time of its failure to an on-line object operator. [ABSTRACT FROM AUTHOR]

In 2010, there were more nuclear power units under construction worldwide than in any year since 1988. Even before Fukushima, however, status indicators for the international nuclear industry were showing a negative trend. Fewer countries are operating nuclear fission reactors for energy purposes than in previous years, and many countries are now past their nuclear peak. Worldwide nuclear production is generally declining, and many new projects are experiencing construction delays. Even if reactors can be operated for an average of 40 years, 74 new plants would have to come on line by 2015 to maintain the status quo, which is impossible given current constraints on fabricating reactor components. Developments in Asia, particularly in China, do not fundamentally change the global picture. The dramatic post-Fukushima decisions in two of the four largest economies, Japan and Germany, and in several other nuclear countries could accelerate the decline of a rapidly aging industry. [ABSTRACT FROM AUTHOR]

Reports on the agreement between the European Bank for Reconstruction and Development and the International Energy Agency to fund the completion of Soviet Union-design nuclear reactors in Ukraine. Details on the closure of Chernobyl's nuclear reactor unit; Types of Soviet Union's reactors; Amount spent by Western Europe for the nuclear safety projects.

Analyzes the factors that contribute to the nuclear reactor accident that occurred in April 1986 in Chornobyl, Ukraine. Description of the conditions that lead to the accident; Importance of identifying the particular characteristics of the reactor to understand the nature of the accident; Demonstration the sequence of events that lead to the explosion.

Ukraine today is a country with 15 nuclear power reactors providing about 50 percent of its electricity. Even if there is no strategic plan to attack Ukraine's nuclear power facilities, can we count on field commanders or local artillery officers to understand the wildly different implications of attacking a nuclear power facility I versus i a coal or gas-fired electricity-generating facility? No modern war has been fought on the territory of a country with nuclear power facilities. [Extracted from the article]

High reliability and security of power unit are basic requirements when the power unit maneuvering mode operation. The reactor stability under disturbances both at steady load and maneuvering load embodies the guarantees of power unit safe and reliable operation. A quantitative measure of the reactor stability is assessed by the axial offset representing the technological characteristics of energy release uniformity, therefore the axial offset minimum deviation is WWER-1000 operation efficiency measure. The power unit capacity automated control systems' influence on axial offset under maneuvering mode is investigated. Considered is the power unit compromise-combined control program, which maintains a constant axial offset value when power unit switching from one power level to another. [ABSTRACT FROM AUTHOR]

Results obtained in the Institute for Nuclear Research of NAS of Ukraine on the development and use of nuclear technologies implemented in the course of the fulfillment of budget themes, scientific-technical and technological projects as well as innovative programs were outlined. [ABSTRACT FROM AUTHOR]

On February 24, 2022, Russia began a military invasion of Ukraine. Missile and air strikes were reported throughout the country, shortly followed by a large ground invasion from multiple directions. Four major theaters developed: the Kyiv offensive, the Northeastern Ukraine offensive, the Eastern Ukraine offensive, and the Southern Ukraine offensive, with continued missile and air strikes far into Western Ukraine. Advancing Russian military units launched an attack and captured the Chernobyl nuclear station. Russian troops dug trenches into the area commonly known as the "Red Forest," violating the established radiation safety measures and threatening security within the Chernobyl Exclusion Zone. The placement of military units in such close proximity to the station also sparked concerns of possible damage occurring to the containment vessel constructed around the station's wrecked fourth reactor. There are 15 operating nuclear reactors in Ukraine. Each is vulnerable to an attack or sabotage that could precipitate a malfunction and possible release of radioactive isotopes. In this short commentary, we will discuss radiobiologic data obtained after the analysis of historical nuclear power plant (NPP) accidents and emphasize new challenges for nuclear security when NPPs are found and are possible targets within a conflict zone., (Published by Oxford University Press on behalf of the Association of Military Surgeons of the United States 2022. This work is written by (a) US Government employee(s) and is in the public domain in the US.)

Neutron fluxes and spectra in the horizontal experimental channels of reactor WWR-M of the Institute for Nuclear Research, National Academy of Sciences of Ukraine (Kyiv) have been calculated using neutron transport Monte Carlo model with fuel enriched in 235U both to 36 and 19.7 %. It is shown that at the very beginning operating with lowenriched fuel, when the reactor core is 28 % filled with "fresh" fuel assemblies, and the remaining cells are filled with beryllium displacers, there is a significant change in the parameters of neutron beams. However, after the reactor will begin to operate at its usual mode, that will be after completing all or most part of the core with fuel assemblies partially burnt out, spectra and fluxes in channels will restore most of their previous values. Some differences are mainly due to changes in composition of the core - the removal of two voluminous vertical water channels located within the core. The work can be helpful to experimenters working with extracted beams at this reactor and so at other reactors that have been converted to low-enriched fuel. [ABSTRACT FROM AUTHOR]

Abstract: Following the explosion of reactor 4 at the Chernobyl power plant in northern Ukraine in 1986, contaminated soil and vegetation were buried in shallow trenches dug directly on-site in an Aeolian sand deposit. These trenches are sources of radionuclide (RN) pollution. The objective of the present study is to provide constraints for the Chernobyl flow and RN transport models by characterising groundwater residence time. A radiochronometer 3H/3He method (t 1/2 =12.3a) and anthropogenic tracers including CFC and SF6 are investigated along with the water mass natural tracers Na, Cl, 18O and 2H. The groundwater is stratified, as evidenced by Na and Cl concentrations and stable isotopes (18O, 2H). In the upper aeolian layer, the Na–Cl relationship corresponds to evapotranspiration of precipitation, while in the underlying alluvial layer, an increase in Na and Cl with depth suggests both water–rock interactions and mixing processes. The 3H/3He and CFC apparent groundwater ages increase with depth, ranging from ‘recent’ (1–3a) at a 2m depth below the groundwater table to much higher apparent ages of 50–60a at 27m depth below the groundwater table. Discrepancies in 3H/3He and CFC apparent ages (20–25a and 3–10a, respectively) were observed during the 2008 campaign at an intermediate depth immediately below the aeolian/alluvial sand limit, which were attributed to the complex water transfer processes. Extremely high SF6 concentrations, well above equilibrium with the atmosphere and up to 1112pptv, are attributed to significant contamination of the soils following the nuclear reactor explosion in 1986. The SF6 concentration vs. the apparent groundwater ages agrees with this interpretation, as the high SF6 concentrations are all more recent than 1985. The persistence of the SF6 concentration suggests that SF6 was introduced in the soil atmosphere and slowly integrated in the groundwater moving along the hydraulic gradient. The apparent age distribution in the lumped parameter models suggests an exponential or piston flow model in the upper geological section, followed by more pronounced mixing processes in the lower section. [Copyright &y& Elsevier]

Abstract: The accident at the Chernobyl nuclear power plant was the worst industrial accident of the last century that involved radiation. The unprecedented release of multiple different radioisotopes led to radioactive contamination of large areas surrounding the accident site. The exposure of the residents of these areas was varied and therefore the consequences for health and radioecology could not be reliably estimated quickly. Even though some studies have now been ongoing for 25 years and have provided a better understanding of the situation, these are yet neither complete nor comprehensive enough to determine the long-term risk. A true assessment can only be provided after following the observed population for their natural lifespan. Here we review the technical aspects of the accident and provide relevant information on radioactive releases that resulted in exposure of this large population to radiation. A number of different groups of people were exposed to radiation: workers involved in the initial clean-up response, and members of the general population who were either evacuated from the settlements in the Chernobyl nuclear power plant vicinity shortly after the accident, or continued to live in the affected territories of Belarus, Russia and Ukraine. Through domestic efforts and extensive international co-operation, essential information on radiation dose and health status for this population has been collected. This has permitted the identification of high-risk groups and the use of more specialised means of collecting information, diagnosis, treatment and follow-up. Because radiation-associated thyroid cancer is one of the major health consequences of the Chernobyl accident, a particular emphasis is placed on this malignancy. The initial epidemiological studies are reviewed, as are the most significant studies and/or aid programmes in the three affected countries. [Copyright &y& Elsevier]

Abstract: The Chernobyl Forum Report from the 20th anniversary of the Chernobyl nuclear power plant disaster concluded that mental health effects were the most significant public health consequence of the accident. This paper provides an updated review of research on the psychological impact of the accident during the 25 year period since the catastrophe began. First responders and clean-up workers had the greatest exposure to radiation. Recent studies show that their rates of depression and post-traumatic stress disorder remain elevated two decades later. Very young children and those in utero who lived near the plant when it exploded or in severely contaminated areas have been the subject of considerable research, but the findings are inconsistent. Recent studies of prenatally exposed children conducted in Kiev, Norway and Finland point to specific neuropsychological and psychological impairments associated with radiation exposure, whereas other studies found no significant cognitive or mental health effects in exposed children grown up. General population studies report increased rates of poor self-rated health as well as clinical and subclinical depression, anxiety, and post-traumatic stress disorder. Mothers of young children exposed to the disaster remain a high-risk group for these conditions, primarily due to lingering worries about the adverse health effects on their families. Thus, long-term mental health consequences continue to be a concern. The unmet need for mental health care in affected regions remains an important public health challenge 25 years later. Future research is needed that combines physical and mental health outcome measures to complete the clinical picture. [Copyright &y& Elsevier]

Abstract: Over the last 20 years, nearly 5000 cases of differentiated thyroid cancer have been diagnosed and treated in the regions of Russia, Ukraine and Belarus in young people previously exposed to the Chernobyl radioactive fallout during childhood. At diagnosis, 60–70% of the Chernobyl-related paediatric thyroid cancers had clinically evident cervical lymph node metastases (N1) and 10–15% had distant metastases (M1). Despite early reports suggesting that the paediatric thyroid cancer cases that developed after exposure to Chernobyl fallout were particularly aggressive, it now seems that the initial presentation and early clinical course of most of these cases are very similar to both non-radiation-associated paediatric thyroid cancers and thyroid cancers that arise after exposure to external beam irradiation. Over an average clinical follow-up period of about 10 years, the disease-specific mortality rate in these paediatric thyroid cancer cases that developed after the Chernobyl accident is quite low (1% or less). As would be expected in paediatric thyroid cancer, short-term recurrence rates range from 7 to 28% in published reports (mean 17%). However, long-term studies of paediatric thyroid cancer suggest that although the 30 year disease-specific mortality rate should be about 1%, the risk of developing structural disease recurrence is nearly 30% (of which 80% are expected to be locoregional recurrences and 20% are probably new distant metastases). Projected over 30 years of follow-up, a 1% disease-specific mortality in this cohort of 5000 patients would equate to about 50 deaths directly attributable to thyroid cancer. However, a 30% recurrence rate would also mean that about 1500 patients may develop a clinically meaningful recurrence that would need to be diagnosed and treated. It is imperative that we continue to work with our colleagues in Belarus, Ukraine and Russia to ensure that this large volume of patients destined to develop clinically significant recurrences are diagnosed and treated in a timely manner. Ready access to modern disease detection tools (serum thyroglobulin, postoperative neck ultrasonography, cytology/pathology support, and radioactive iodine scanning) and treatments (surgery for recurrent disease, radioactive iodine therapy) in their major academic centres are mandatory if we expect to achieve the excellent clinical outcomes that should be seen when paediatric thyroid cancer recurrence is diagnosed early and treated appropriately. [Copyright &y& Elsevier]

Abstract: The question whether radiation-induced thyroid cancer differs by its molecular biology from sporadic disease still remains. Studies on tissue from patients who developed thyroid cancer after the Chernobyl accident have provided a unique opportunity to look for biological consequences of low-dose irradiation by comparing the gene expression profile of sporadic papillary thyroid cancer (PTC), whose aetiology is unknown, and PTC induced by internal radiation. So far, four transcriptomic studies comparing radiation-induced and sporadic thyroid cancer have been reported. However, no final conclusion has been drawn regarding the presence of a radiation signature, as either no difference was noted or the reported differences were not sufficiently convincing due to the low number of cases analysed or to the presence of confounding factors. The list of putative biological and clinical factors that may influence the PTC gene expression profile is long, but there are sufficient data reported in the literature to link expression profiles with differing pathological variants of PTC. The comparison of expression profiles in the tumour samples allows the search for a radiation signature, whereas the comparison of expression profiles of the normal contralateral tissues offers a substantial opportunity for assessing the existence of a susceptibility to radiation that could be responsible for tumour development. We have undertaken this analysis as part of a European Union-funded project, GENRISK-T. Gene expression profiles were investigated in tumours that have arisen in the population exposed to fallout from Chernobyl (i.e. born before 26 April 1986) and were compared with profiles of tumours of similar pathology arising in an age-matched population, residing in the same geographical area (same ethnicity) and born after 1 January 1987. RNA samples from these tumours and their contralateral normal tissues were obtained from the Chernobyl Tissue Bank. Several lines of evidence suggest that the predisposition to developing cancer after radiation exposure is variable in the general population and may be measurable from gene expression. [Copyright &y& Elsevier]

Abstract: The only unequivocal radiological effect of the Chernobyl accident on human health is the increase in thyroid cancer in those exposed in childhood or early adolescence. In response to the scientific interest in studying the molecular biology of thyroid cancer after Chernobyl, the Chernobyl Tissue Bank was established. The project is supported by the governments of Ukraine and Russia, and financially supported (in total around US$3million) by the European Commission, the National Cancer Institute of the USA and the Sasakawa Memorial Health Foundation of Japan. The project began collecting a variety of biological samples from patients on 1 October 1988, and has supplied material to 21 research projects in Japan, the USA and Europe. The establishment of the Chernobyl Tissue Bank has facilitated co-operation between these research projects and the combination of clinical and research data provides a paradigm for cancer research in the molecular biological age. [Copyright &y& Elsevier]

Abstract: For many years, gene alterations of the mitogen activated protein kinase pathway have been investigated in papillary thyroid carcinomas (PTC) and the radiation-specific induction of Ret/PTC rearrangements has been discussed in the published literature. According to recent studies, these alterations are now considered as age-related changes rather than radiation-specific changes in PTC. Thus, there is a strong motivation to search for novel alterations that might represent radiation-specific markers in PTC. DNA copy number alterations (CNAs) are frequent in human cancers and are also prevalent in PTC. However, the only way to tease out radiation-specific CNAs is a comparative analysis of CNAs from closely matched tumour cohorts, as various factors such as the age of patients or the histology of tumours also influence the type and frequency of CNA. Therefore, this review focuses on the current knowledge on CNAs in PTC and on future strategies to identify radiation-specific changes in these tumours. [Copyright &y& Elsevier]

Simple Summary: Analysis of the groups of young Ukrainian patients (aged ≤28 years) with radiogenic and sporadic papillary thyroid carcinomas (PTCs) showed that the frequency of BRAFV600E was increasing with patient age, consistently remaining lower in radiogenic PTCs. In both etiopathogenic groups, the BRAFV600E-positive PTCs more frequently had a dominant papillary growth pattern, smaller tumor size, higher Ki67 labeling index, and a frequency of the major indicators of tumor invasiveness that is lower than or equal to that of the BRAFV600E-negative tumors. Comparison of the BRAFV600E-positive PTCs across the groups found a virtual absence of differences, while the BRAFV600E-negative tumors differed markedly and displayed a higher frequency of invasive tumor features in the radiogenic PTCs. Hence, there is evidence that BRAFV600E does not confer a more aggressive course of PTC in young patients regardless of tumor etiology. Histopathological changes in the fusion oncogene-driven papillary thyroid carcinomas (PTCs) from children and adolescents exposed to Chernobyl fallout have been extensively studied. However, characteristics of the radiogenic BRAFV600E-positive PTCs, whose proportion is growing with time, are not well described yet. We analyzed the relationship between the BRAFV600E status (determined immunohistochemically with the VE1 antibody) and the clinicopathological features of 247 radiogenic and 138 sporadic PTCs from young Ukrainian patients aged ≤28 years. The frequency of BRAFV600E was increasing with patient age, consistently remaining lower in radiogenic PTCs. In both etiopathogenic groups, the BRAFV600E-positive PTCs more frequently had a dominant papillary growth pattern, smaller tumor size, higher Ki67 labeling index, and a frequency of the major indicators of tumor invasiveness that is lower than or equal to that of the BRAFV600E-negative tumors. Comparison of the BRAFV600E-positive PTCs across the groups found a virtual absence of differences. In contrast, the BRAFV600E-negative radiogenic PTCs displayed less frequent dominant papillary and more frequent solid growth patterns, lower Ki67 labeling index, and higher invasiveness than the BRAFV600E-negative sporadic tumors. Thus, BRAFV600E is not associated with a more aggressive course of PTC in young patients regardless of etiology. The major clinicopathological differences between the radiogenic and sporadic PTCs are observed among the BRAFV600E-negative tumors. [ABSTRACT FROM AUTHOR]

Abstract: Within the framework of an European Commission sponsored activity, an assessment of the deterministic safety technology of the ‘post-Chernobyl modernized’ Reactor Bolshoy Moshchnosty Kipyashiy (RBMK) has been completed. The accident analysis, limited to the area of Design Basis Accident, constituted the key subject for the study; events not including the primary circuit were not considered, as well as events originated from plant status different from the nominal operating conditions. Therefore, the notorious Chernobyl Unit 4 event was outside the scope of the investigation. Following the evaluation of the current state of the art in the area including the identification of critical issues, targets for the analysis were established together with suitable chains of computational tools. The outcomes from this part of the study are (a) the list of transient scenarios whose parameter values are assumed to constitute the boundaries for the evolution of any relevant safety transient and; (b) a set of computational tools with characteristics consistent with current technological achievements, suitable for performing safety analyses. The availability of computational tools, including codes, nodalisations and boundary and initial conditions for the Smolensk 3 NPP, brought to their application to the prediction of the selected transient evolutions that, however, are not classified as licensing studies. The results demonstrated proper safety margins and relatively long time constants associated with the huge values for the ratios between mass of moderator and mass of coolant and unit generated power. The results at the item above, suggested a qualitative, though non rigorous, comparison between accident analysis aspects in LWR and RBMK having the main purpose to show strengths in RBMK safety features heavily criticized not always in a consistent way following the Chernobyl event. The results of supporting analyses for the present paper are discussed in five companions papers in this Journal volume. The second (over six) and the third paper deal with the RBMK Main Coolant Circuit and Confinement thermal-hydraulic performance, respectively. Key specific issues in the RBMK safety technology, constituted by addressing of the “Multiple Pressure Tube Rupture (MPTR)” and by the application of coupled three-dimensional neutron-kinetics thermal-hydraulics, are discussed in the fourth and fifth papers. The proposal to instrument the core channels (ICM=Individual Channel Monitoring) has been formulated in this context and is discussed in the sixth companion paper. [Copyright &y& Elsevier]

When a reactor at the Chernobyl atomic energy plant in Ukraine caught fire, it sends radioactive clouds across large part of Europe. A hastily constructed concrete cover dubbed as the sarcophagus was constructed to contain the remnants of the destroyed reactor. The article examines the consequences of the world's largest nuclear catastrophe and the long-awaited agreement for engineering a new object shelter in Chernobyl. [ABSTRACT FROM AUTHOR]

Abstract: Many researchers have reported that the root cause of the Chernobyl accident has not been clarified still now. Since many of them discussed the accident without a precise thermal-hydraulic investigation, thermal-hydraulic calculations coupled with neutronic calculations have been done on the basis of the recorded result at the Chernobyl Unit-4. Plant configurations and operational conditions were given to the code on the basis of reported result and published papers. Calculation could trace plant parameters from 1:19:00 to the first power excursion without any discrepancies measured at the Chernobyl Unit-4. Reactivity slightly smaller than 1β by the positive scram is concluded as a possible direct cause of the accident, which acts as a trigger to increase the reactor power. Other possibilities as a trigger of the accident such as cavitation in pumps and pump coast-down were investigated. The importance of the calculation from the stable condition is also described in this paper in order not to bring unnecessary assumptions into the calculation. [Copyright &y& Elsevier]

After the Chernobyl accident in 1986, the Swedish Parliament decided that nuclear power production should gradually be phased out. In 1997, the Act on Phasing-Out Nuclear Power was passed. This Act empowers the Swedish Government to decide to close nuclear reactors. Under Act, the owner of a reactor, which is closed, is entitled to compensation from the state. On 5 February 1998, the Government decided to close one reactor in Barsebäck. The owner of the reactor and its parents challenged the legality of the Government's decision. The applicants alleged, inter alia, that the decision violated the Instrument of Government, the European Convention for the Protection of Human Rights and Fundamental Freedoms, EC law and the Energy Charter Treaty. On 16 June 1999, the Supreme Administrative Court rejected the complaints. Sydkraft AB then brought complaints to the European Commission alleging, inter alia, that the Supreme Administrative Court had failed to refer to the European Court of Justice questions of interpretation of Article 86(1) and under the Environmental Impact Assessment (EIA) Directive. An agreement for compensation was entered into in November 1999. In 2002, the European Commission found that Sweden had not complied with its obligations under the EIA Directive. In December 2004, the Government decided to close Barsebäck 2, which decision resulted in a further agreement on compensation. [ABSTRACT FROM AUTHOR]

The dissolution of the Soviet Union created many problems for the health care systems of the New Independent States (NIS). To address these problems, the U.S. Secretary of State convened a coordinating conference in Washington, D.C., on 22-23 January 1992 at which more than 50 nations and organizations were represented. After this conference, an expert medical working group visited 10 republics of the NIS during February and March 1992. Hospitals, public health facilities, and pharmaceutical plants and distribution sites were visited to assess the health care needs of a large population in a vast geographic area. It was concluded that the massive health care system of the Soviet Union remains largely intact but has major economic and supply deficiencies. The assessment process and findings in one republic, Ukraine, are presented. Ukraine was chosen because of its size, location, and representativeness. [ABSTRACT FROM AUTHOR]

After the accidents at Chernobyl, the Soviet Union, and in Goiania, Brazil, there is increasing concern about the medical risks from radiation accidents. This overview summarizes the principles of nuclear energy, the biologic effects of accidental radiation exposure, the emergency response to nuclear accidents, and approaches to treating radiation injuries. Also discussed are the related issues of reactor safety, the disposal of radioactive waste, and the proliferation of nuclear weapons. With the increasing use of radioactive materials for power, weapons, and medical diagnostics, the medical community needs to understand the health consequences of radiation exposure. [ABSTRACT FROM AUTHOR]

There is a consensus that Chernobyl accident has induced thyroid cancer increase in children and adolescents. The UNSCEAR report concluded that no somatic disorders other than thyroid cancer were caused by radiation exposure due to the accident except for acute radiation sickness occurred to the people within the Power Plant at the time of the accident. A hypothesis is discussed in this paper that the increase of thyroid cancer was caused predominantly by the screening, overdiagnosis, and registration of nonirradiated persons as Chernobyl victims. A mechanism of thyroid cancer overdiagnosis is described that can be active even today, causing hypertherapy. Older neglected tumors found by the screening shortly after the Chernobyl accident or brought from noncontaminated areas were misclassified as aggressive radiation-induced cancers. Therefore, supposed markers of the radiationinduced thyroid cancer, such as the RET rearrangements, are probably associated with disease duration and tumor progression. The screening effect is obviously dependent on the basis level of medical surveillance: the higher the level, the smaller the screening effect. Absence of any significant increase of thyroid cancer after the Fukushima accident in spite of the vigorous screening would certify the high level of health care in Japan especially for children. [ABSTRACT FROM AUTHOR]