Handling spent nuclear fuel at a temporary storage site in Guba Andreev

Spent nuclear fuel has been stored in dry-storage units at a shore base of the naval fleet for 35–45 year. The total activity of the spent nuclear fuel is 170 PBq. This article presents data which characterize the state of the fuel (from normal to defective), the radiation conditions, and information on the individual and collective irradiation dose to workers. The results of an inventory check of the cells and jackets which contain fuel assemblies are presented. The corrosion processes are described and ideas for handling the spent fuel at the RT-1 plant of the Mayak Industrial Association, including handling fuel assemblies and jackets in cases, are described. __________ Translated from Atomnaya énergiya, Vol. 101, No. 1, pp. 56–61, July, 2006.     

Computational-experimental determination of the temperature of the components of a shipping container with spent fuel

The results of a determination of the expected temperatures of the structural components of the container with long-term dry storage and shipment of spent nuclear fuel from the AMB reactors at the Beloyarakaya nuclear power plant, under normal and accident conditions, are presented. The requirements for its thermalprotection characteristics are formulated on the basis of normative-technical documentation, and the basic assumptions and initial prerequisites, used to perform the calculations, are presented. The computational-experimental method is used together with the results of tests performed on a prototype model to confirm the possibility of ensuring the required temperatures of the basic components of the container and the fuel assembly. __________ Translated from Atomnaya énergiya, Vol. 100, No. 6, pp. 428–431, June, 2006.     

Improvement of the technology for the long-term storage of RBMK-1000 spent fuel

Proposed changes in handling spent nuclear fuel, which are noteworthy in that they mainly dispense with regenerating it and instead use long-term intermediate storage, require a review of storage design concepts. The safety of the handling in the case of intermediate storage is increased by using the optimum water-chemical regime and a conserving mixture of calcium oxide and carbonate. An investigation of the corrosion of the structural materials of RBMK-1000 spent fuel showed that when a mixture of CaO and CaCO₃ is present, local forms of corrosion of the fuel-element jackets and containers are eliminated, and an additional barrier is formed for keeping the containers hermetically sealed, which stops the leakage of the soluble part of the fuel from unsealed fuel elements into the container water. Radionuclides are withdrawn from the solution by sorption on the precipitated calcium carbonates and oxyhydrates. Safe storage is thereby achieved in a compacted system at 3–6 t/m² for fifty years or more. VNIPIéT. Translated from Atomnaya énergiya, Vol. 86, No. 5, pp. 383–391, May, 1999.     

Kinetics of the leaching of90Sr from fuel particles in soil in the near zone of the chernobyl nuclear power plant

A method is presented for calculating the fraction of⁹⁰Sr included in fuel particles in soil. Data concerning the change in forms of the occurrence of⁹⁰Sr in different soils in the 30-km zone, at different distances from the Chernobyl nuclear power plant, were used to obtain the kinetic characteristics of its leaching: the first-order rate constant and the normalized rate of solution. Depending on the direction and distance from the nuclear power plant, the first-order leaching rate constant varies from 3·10⁻⁵ to 2·10⁻³ days⁻¹ and the normalized rate of solution of the fuel matrix varies from 1·10⁻⁵ to 6.1·10⁻⁴. It was not found possible to clearly identify the influence of the distance from the nuclear power plant on the leaching rate in the northern and western sectors. In contrast, in the southerly and south-easterly directions a clear tendency was observed for the leaching rate to increase with increasing distance from the nuclear power plant. Taifun Scientific Production Enterprise. Translated from Atomnaya énergiya, Vol. 86, No. 2, pp. 129–134, February, 1999.     

Drop tests of TUK-84 for accident conditions during shipment

Tests for mechanical damage of the TUK-84 shipment assembly, used for shipping and dry storage of spent nuclear fuel, with the container drop from a height of 9 m on a rigid base and from a height of 1 m on a steel pin are described. The basic data from the measurements of the impact parameters are presented, the results of tests for defects and post-test checking are presented, and results of acceptance tests for mechanical damage are also presented. __________ Translated from Atomnaya énergiya, Vol. 100, No. 6, pp. 445–448, June, 2006.     

Subcritical power reactor with irradiation by a beam of accelerated protons

Conclusions The conversion of a nuclear power plant to operation with quite deeply subcritical reactors eliminates the primary reason for the appearance of reactivity accident situations associated with the probability of the reactor being transferred into a subcritical state and runaway of this state. There is no doubt that a nuclear power plant can in principle operate on the basis of a subcritical reactor and a high-power proton accelerator. To answer the question of whether or not it is desirable to equip nuclear power plants with accelerators, it must be kept in mind that besides achieving the main goal — complete elimination of the possibility of reactivity accidents and as a consequence of such accidents emission of solid radioactive products of uranium fission with enormous consequences for ecological and economic damage — such improvements have other important consequences. These include, for example, the possibility of constructing fuel cycles on the basis of the fuel depleted with respect to fissioning isotopes (^233,235U,²³⁹Pu), which will make it possible to decrease substantially the fuel component of the cost of a nuclear power plant; the possibility of more efficient utilization of nuclear fuel by increasing significantly the interval between loadings; and, control of the power and shielding of a reactor by changing the beam current of the accelerator. All this will make it possible, in principle, even at today's level of development of reactor and accelerator technology to build a subcritical power reactor with external irradiation with a high-energy particle beam. Institute of High Energy Physics. Translated from Atomnaya énergiya, Vol. 77, No. 4, pp. 300–308, October, 1994.     

Nuclear fuel in the shelter

The stages of multiyear investigations of the fuel-containing materials remaining in the Shelter after the accident at the Chernobyl nuclear power plant, including the determination of their total amount and the physicochemical properties, are described. Thus far ∼150 tons of fuel from the destroyed reactor have been found inside the Shelter. Another ∼ 30 tons could be located in sites which are still inaccessible to investigators. One section of this paper is devoted to the analysis of the possibility of the decomposition of the lava-like fuel-containing materials during a long storage period (ten years) after the Shelter is converted into an ecologically safe system. Questions concerning the development of a system for monitoring fuel-containing materials are discussed. __________ Translated from Atomnaya énergiya, Vol. 100, No. 4, pp. 258–267, April, 2006.     

Analysis of criticality in shipment and storage of fuel at a nuclear power plant with a VVÉR reactor

The substantiation of nuclear safety during shipment and storage of fresh and spent fuel at nuclear power plants with VVéR reactors is examined in the light of the more stringent nuclear safety rules. Possible technical measures for satisfying the safety criterion are examined, for example, the concept of subcritical fresh fuel. An example of the estimation of the probability of the formation of a critical mass as result of fuel assemblies falling randomly out of a container is presented. Certain characteristic features of the calculation of the neutron-physical characteristics of fuel in a cooling pond are presented, for example, the nonconservative nature of a separate analysis in the infinite approximation. 4 figures, 5 references. OKB “Gidropress”. Translated from Atomnaya éneriya, Vol. 87, No. 1, pp. 11–16, July, 1999.     

Method for liquidating the consequences of the chernobyl accident

Conclusions The proposed method is a safe, technically feasible, and economically acceptable solution to the problem of liquidating the focus of the environmental contamination at the Chernobyl nuclear power plant. The radioactive substances, materials, and objects will be removed from “Cover” and imperfect storage sites within the 100-km zone around the Chernobyl nuclear power plant and placed in storage sites which meet modern requirements. The storage of the wastes will be controllable and monitorable. The object “Cover” will be liquidated. Main Scientific Center of the Russian Federation — Physics and Power Engineering Institute. Translated from Atomnaya énergiya, Vol. 78, No. 3, pp. 214–217, March, 1995.     

燃料组件修复过程中单根燃料棒损坏影响分析

以核电厂燃料组件修复过程中单根燃料棒损坏释放的放射性物质为分析对象,就放射性物质释放对组件修复的工作人员产生的累积有效剂量进行评估,对向环境释放的气态流出物的放射性总活度进行计算,并对气态流出物排放监测的影响开展分析。分析结果表明单根燃料棒损坏后,执行燃料组件修复的每位工作人员接受的累积有效剂量为12.2 mSv,低于GB 18871—2002规定的工作人员职业照射年平均有效剂量限值20 mSv;向环境释放的气态流出物中惰性气体与碘的放射性总活度分别为3.51×10¹¹ Bq和2.17×10⁸ Bq,远小于GB 6249—2011规定的年排放控制值6.0×10¹⁴ Bq和2.0×10¹⁰ Bq。燃料棒损坏后40 min烟囱排气惰性气体测量仪的读数小于1.0×10¹¹ Bq/h,核电厂无需进入应急待命状态。     

External radiation of a container used for dry storage of spent VVER-1000 nuclear fuel from the Zaporozhie nuclear power plant

The program MCNP (Monte Carlo Modeling of radiation transfer) is used to calculate the characteristics of external neutron and γ radiation from a ventilated dry-storage container for spent nuclear fuel. Data are obtained on the spatial, energy, and angular distribution of the neutron and γ-ray flux outside the container and the dependence of the dose rate on the storage time of the spent fuel is determined. It is shown that γ-rays make the main contribution to the dose rate on the side surface of the container and neutrons do on the cover. The computed dose rate is 1.4 times higher than the measured value on an individual loaded container at the Zaporozhie nuclear power plant.     

Reactor with a fast-resonance neutron spectrum, cooled by supercritical-pressure water with a bidirectional coolant flow scheme

A scheme for circulating coolant and cooling the core that has advantages over the designs of similar nuclear power systems is proposed for light-water reactors with supercritical coolant parameters and a fast-resonance neutron spectrum. A negative void coefficient of reactivity is obtained for the entire run of a fuel assembly without building a blanket. A more uniform distribution of the energy release over the core volume is achieved without using complicated fuel-enrichment schemes. The nonuniformity of the coolant temperature distribution at the core exit is decreased. The fuel assemblies operate with a much lower temperature drop over the core height. The core has a small reactivity excess on burnup and a BR of about 1, for which the most difficult operating regimes (flooding with cold water) can be handled with standard means (placement of absorbing organs of the safety and control system in ∼2/3 of the fuel assemblies). __________ Translated from Atomnaya énergiya, Vol. 100, No. 5, pp. 349–356, May, 2006.     

Requirements for 21st centry nuclear power plants

The development of energy production in the 21st century will be subject to more uniform per capita and regional consumption. Among the competing sources of energy, the positive qualities of nuclear power-unlimited fuel resources, high energy intensiveness, and ecological compatibility with the possibility of the wastes being highly concentrated—predetermine the development of large-scale nuclear power. The conditions for the development of such nuclear power are its ecological effectiveness and safety (of the reactors and the fuel cycle with the production of wastes), nuclear fuel breeding with adequate characteristics, and guarantees of nonproliferation of fissioning materials. Continuity in the development of nuclear power dictates the requirements for reactor systems in the near and distant future. The acceptable level of safety is closely related to the scales of nuclear power and the applications of nuclear energy sources. However, progress in decreasing the potential danger of reactors and decreasing the cost of protective systems is unavoidable. In choosing new directions, it is important to demonstrate the new qualities in the solution of the problems facing nuclear power in the future. An adequate diversity of reactor technologies could exist in the future. The requirements that will face nuclear power plants in the future stages of development and the expected stages of this development are discussed. The jourmal variant of this report at the 10th annual conference of the Nuclear Society “From the first nuclear power plant in the world to power engineering of the twenty-first century” (June 28–July 2, 1999, Obninsk) Russian Science Center “Kurchatov Institute”. Translated from Atomnaya énergiya, Vol. 88, No. 1, pp. 3–14, January, 2000.     

Innovative development of nuclear power in Russia

The basic principles for performing analysis and the systems requirements for large-scale nuclear power in our country are formulated. The problems of modern nuclear power are examined and ways for modern nuclear power to transition to innovative development while satisfying these systems requirements for fuel use, handling spent fuel and wastes, and nonproliferation are indicated. The basic scenario of innovative development in the near term (up to 2030) is based on using predominantly ²³⁵U as fuel and water-moderated water-cooled reactors, which have been well mastered, for increasing nuclear capacities with limited introduction of fast reactors for solving the problem of spent fuel from thermal reactors. In the long term (2030–2050), a transition to ²³⁸U as the primary raw material with fast reactors predominating and complete closure of the nuclear power fuel cycle will be made. The journal variant of a report “New-Generation Nuclear Energy Technologies” presented at a meeting of the Scientific and Technical Council of Rosatom, Moscow, September 27, 2006. __________ Translated from Atomnaya énergiya, Vol. 103, No. 3, pp. 147–155, September, 2007.     

Nuclear fuel and the characteristics of aerosol formation in the object “Cover”

High-temperature atomization of materials, transfer of elements into the gas phase and the condensation of the elements, occurred during the active stage of the accident at least at a local point of the reactor. As a result of these processes, in some cases the ratio Pu/U in large spherical particles of the dispersed phase differ substantially from the ratio characteristic for the average nuclear fuel in the fourth power generating unit of the Chernobyl nuclear power plant. Therefore, the term “average nuclear fuel” with respect to materials containing nuclear fuel in the object “Cover” is inadequate. Moscow Technological Center “Cover,” Ukrainian Academy of Sciences. Yu. N. Lobach Science Center “Institute of Nuclear Research,” Ukrainian Academy of Sciences. Translated from Atomnaya énergiya, Vol. 82, No 1, pp. 39–44, January, 1997     

Transition to a new size of the sanitary-protective zone of a nuclear power plant

In our country, in accordance with world-wide practice, nuclear power plant safety is ensured by the systematic implementation of the concept of deeply esheloned protection based on the use of a system of physical barriers, including a fuel matrix, fuel-element cladding, boundary of the reactor coolant loop, airtight sealing of the reactor system, and radiation protection. In the Soviet Union, in contrast to other countries, an additional barrier was introduced in the construction and operation of nuclear power plants-a sanitary-protective zone separating the atomic power plant from housing developments. The results achieved in nuclear power give every basis for concluding that it is in principle possible to reject the use of part of the environment for protecting the public from the radiation effects of a nuclear power plant operating under normal conditions, i.e., the size of the sanitary-protective zone of the territory of the industrial site of a nuclear power plant can be limited in accordance with the operative law and normative base. The results of calculations and validations are presented. __________ Translated from Atomnaya énergiya,Vol. 100, No. 6, pp. 458–465, June, 2006.     

Residual energy release and actinide and fission product radiotoxicities during long-term storage of high burnup spent VVÉR fuel

The residual energy release and radiotoxicity of spent high burnup VVéR-1000 fuel during long-term storage is investigated as a function of time. The contributions of α, β, γradiation and radiotoxicity-the maximum admissible activity of nuclides in air and water-are taken into account in the calculations of the energy release. The data presented can be used to develop methods for handling spent nuclear fuel from prospective power reactors. __________ Translated from Atomnaya énergiya, Vol. 102, No. 5, pp. 292–296, May, 2007.     

Validation of nuclear and radiation safety of a container for spent amb reactor fuel assemblies at the Beloyarskaya nuclear power plant

An approach is proposed for validating the nuclear and radiation safety of a container for spent fuel assemblies from AMB-100 and-200 reactors at the Beloyarskaya nuclear power plant. To validate the radiation safety, the characteristics of fuel assemblies and their classification according to the average fuel burnup in the casing, and the intensities of n and γ radiation in the casing are analyzed. Nuclear safety is validated on the basis of the concept of a “model” casing. This model makes it possible to obtain an upper estimate of the effective coefficient of neutron multiplication for all real casings with fuel assemblies. Calculations are used to determine the minimum necessary thickness of the vessel, bottom, and cover for 17-and 35-place casings. It is shown that no special neutron protection is needed. The container design to be developed meets the IAEA and OPBZ-83 safety standards. __________ Translated from Atomnaya énergiya, Vol. 100, No. 6, pp. 423–428, June, 2006.     

Assessment of the quality and activity of the radionuclides in the fuel cycles of a three-component structure of nuclear power

A three-component structure of nuclear power with a closed nuclear fuel cycle is examined. In addition to the existing thermal and fast reactors the system contains a liquid-salt reactor for closing the fuel cycle with respect to actinides. The quantity and activity of the radionuclides are analyzed for promising variants of the structure of nuclear power and the uranium-plutonium, thorium-uranium, and uranium-plutoniumthorium closed fuel cycle. It is concluded on the basis of calculations and analysis, taking into account the life cycle from production of the fuel to the burial of the wastes, that the uranium-plutonium-thorium fuel cycle is more advantageous than the uranium-plutonium and thorium-uranium fuel cycles. __________ Translated from Atomnaya énergiya, Vol. 101, No. 3, pp. 214–221, September, 2006.     

新燃料组件运输容器加速度计跳离事件的处理方法研究

新燃料组件运输容器上的加速度计是用于监测燃料组件运输过程中的异常冲击。加速度计的跳离表示在运输过程中可能存在对燃料组件产生损坏的载荷。近年来,国内核电站发生多起新燃料组件运输容器的加速度计跳离事件。发生运输容器的加速度计跳离事件后,需对事发燃料组件的机械完整性以及可用性进行评估,并判断其是否可入堆使用。本文在对加速度计的作用原理及加速度计跳离过程进行深入分析基础上,提出了一种新燃料组件运输容器加速度计跳离事件的通用处理方法。利用该通用处理方法对某核电站近年来发生的新燃料组件运输容器加速度计跳离事件进行了处理,处理结果得到了业主的采纳。本文中提出的加速度计跳离事件通用处理方法,可为国内核电站后续加速度计跳离事件的处理提供重要的参考和依据。