First results of ecological rehabilitation of a temporary storage site for spent nuclear fuel and radioactive wastes in Guba Chervyanaya

One of the most important problems arising in the comprehensive salvaging of nuclear submarines and the ecological rehabilitation of previous shore-based technical bases is the handling of the spent nuclear fuel. For the temporary storage site in Gremikha this is the preparation and removal of about 800 fuel assemblies and eight spent parts removed from Alpha class boats. The unsatisfactory state of the infrastructure and the sanitary-hygienic support on the object made it impossible remove the spent fuel immediately. Several years of work were needed to remove at the end of 2008, following the standard scheme, the first batch of 294 fuel assemblies for reprocessing at the Industrial Association Mayak. This was accomplished with the active and financial support of the French Atomic Energy Commission, the European Bank for Reconstruction and Development, and the European Commission (TACIS).     

An assessment of spent nuclear fuel storage demands under uncertainty

This paper attempts to draw quantitative prospects of spent nuclear fuel (SNF) management in Japan, with emphasis on uncertainty of storage needs for SNF up to the year 2050. In a medium term up to the years 2020–2030, the storage need for SNF can be projected with relatively high accuracy as it steadily increases up to the level of 5000 tonnes of uranium (tU), which requires timely deployment of storage facilities accordingly. In a longer term up to 2050, a number of aspects may give influences on the SNF management strategy, which are analyzed in different sets of scenario assumptions. The results of quantitative simulation runs showed that the storage need for SNF will increase up to the level of 10,000 tonnes of heavy metals (tHM) in the Base Case, while it would further grow to 20,000–25,000 tHM in the Risk Management Cases. Careful attentions should be given to the point that not just quantity but characteristics of SNF to be stored will differ significantly among the simulation cases, such as from lower to higher burnup, uranium and MOX (mixed oxide) fuels. The results imply Japan's SNF management may require elaborate strategies, which consists of effective and timely measures into the future.     

Thermal analysis of the heat exchanger for a spent nuclear fuel storage pool

A numerical solution is provided to predict the transient temperature distribution of both fluids in the U-tube heat exchanger of a spent nuclear fuel storage pool. A finite element method, with the Galerkin approach, is used to solve the set of five partial differential equations of energy conservations, with arbitrary inlet and boundary conditions. The results are obtained with very low computation time, through a computer program on a CDC 730, which can be easily linked to other thermal hydraulic codes for the storage pool.To show the capabilities of the program, some results are presented, concerning step response and other transient operations of the exchanger.The validation of the method has been performed comparing the numerical results with the exact steady state analytical solutions available in literature; the agreement is very satisfactory.     

Information-analytical system for tracking the rehabilitation of a temporary storage facility for spent nuclear fuel and radioactive wastes in the village of Gremikha

An information-analytical system for solving various problems facing developers and implementing agencies at all stages of work has been developed at Russian Science Center Kurchatov Institute as part of a project for ecological rehabilitation of a temporary storage site located in the village of Gremikha for nuclear fuel and radioactive wastes. The information-analytical system accumulates all information on the project: technical characteristics of the objects, cartographic information, documentation, and information on the participants of the project, technologies, and equipment. The centralized storage of the initial data and the data obtained from examinations makes its use effective for all participants of the project. Analysis of the stored information and the formation of structured sets of data are necessary for planning further work on the project and choosing concrete design solutions, exchanging information between participants in the work, and providing information to state organs and the public.     

Handling spent nuclear fuel and radioactive wastes on the shore servicing base in Gremikha

The situation which has developed at the shore base in Gremikha involving fuel assemblies in the removed cores of water-moderated water-cooled reactors (first-generation submarines), which are located on an open site in containers and receiving chambers, and involving solid and liquid radioactive wastes present at the base is examined. Data are presented on the number of fuel assemblies and their technical state and on the state and amount of solid and liquid radioactive wastes. Suggestions on what should be done with the fuel assemblies and wastes are discussed. __________ Translated from Atomnaya énergiya, Vol. 101, No. 1, pp. 61–65, July, 2006.     

Heat transfer in spent fuel storage

Heat transfer and fluid flow analyses are described for the underwater storage of spent fuel from nuclear power reactors. The analytical methods and supporting test measurements have been employed by General Electric Company in the design and licensing of two spent fuel storage systems: (a) High-density racks for storage of BWR spent fuels in at-reactor water basins [1]. (b) Multi-element baskets for storage of BWR and PWR spent fuel in GE's facility near Morris, IL [2]. The results show that natural convection flow through individual spent fuel bundles provides safe and effective temperature control. Under accident conditions the relatively slow dynamics of the basin system permits timely repair to a loss of basin cooling capability without significant risk to the spent fuel in storage.     

Thermal criteria for terminal storage of spent nuclear fuel assemblies in bedded salt

Design considerations, particularly thermal design considerations, for terminal storage of spent nuclear fuel in a bedded salt repository are discussed in a set of four papers which address: thermal criteria, uncoupling thermal problems, near-field temperatures, and optimization of mine arrangement. This paper outlines the thermal criteria used in the conceptual design of a bedded salt repository and discusses the historical rationale behind developments of each criterion.     

Uncoupling thermal problems of terminal storage of spent nuclear fuel assemblies in bedded salt

Spent nuclear fuel assemblies stored in bedded salt can be modeled with a large array of dimensioned decay heat sources (spent fuel assemblies) in an extended thermal conducting media. Although a finite-difference or finite-element representation of the total storage facility could be established, regions of the repository should be analyzed separately since a model of the total repository would require formidable digital computing capacity. This paper explains the basis for thermally analyzing the total storage facility with separate models for the stored fuel assembly package and the salt medium. In addition, the effect of fuel assembly packaging on the maximum fuel temperature, the related problems of fuel handling prior to storage, and uncoupling of the effects of mine ventilation and conduction in the salt medium are discussed.     

Topics of research and development on concrete cask storage of spent nuclear fuel

This paper addresses topics of research and development (R&D) being challenged for realization of concrete cask storage of spent nuclear fuel in Japan. Comparison between metal cask storage and concrete cask storage is addressed. Background of these R&D and current status of technology on spent fuel storage are described. Need and design concepts of concrete cask storage technology, tests and evaluation of integrity of spent fuel, materials, concrete casks under normal and accident conditions, monitoring technology, etc. are systematically arranged and introduced. Topical problems of these R&D are described.     

Seismic isolation of pool-type tanks for the storage of nuclear spent fuel assemblies

Seismic isolation of pool-type nuclear spent fuel storage tanks requires careful investigation of dynamic behavior of the fluid–structure–isolator interaction system to satisfy the requirements of safety functions and the prevention of nuclear criticality. This paper presents the investigation, results and discussions on the seismic design considerations of isolated pool-type tanks for the storage of nuclear spent fuel assemblies. A three-dimensional boundary element-finite element method is presented for the analysis of the fluid–structure–isolator systems in time domain. Scaled model tests were performed to verify the numerical method and to study the dynamic behavior of isolated pool-type storage tanks. Important factors affecting the dynamic behavior of tanks with a fixed base are further investigated as is the case for isolated tanks using base isolators with different mechanical properties. The base isolators are the high damping rubber-bearing type and are modeled using a bilinear analysis model. Based on the numerical analysis and experimental results, some conclusions and discussions on the design considerations for isolated storage tanks are presented. In general, it is shown that careful selection of mechanical properties of the isolators with a certain lower limit on the effective frequency can guarantee the reduction of the dynamic responses of the storage tanks and the enhancement of the stability of stored spent fuel assemblies against earthquake excitations.     

Handling spent nuclear fuel from the research reactors of the Russian Science Center Kurchatov Institute

Shipping out the spent fuel of the research reactors at the Institute for reprocessing is examined. The spent fuel is characterized by a great diversity of structural characteristics of the fuel assemblies and fuel elements, fuel compositions, and the enrichment, burnup, and cool-down times of the fuel as well as the state of the components of the assemblies and the structural materials. A classification and quantitative indicators of the accumulated spent fuel from the standpoint of the modern state of its reprocessing technology and the requirements for delivery to the Mayak Industrial Association are presented. The structural features of the TKU-19 and -128 shipment containers are presented, and the loading of spent fuel assemblies into them for shipment to reprocessing is described. The plans and goals of further work on the removal of spent fuel from the Institute’s territory are presented. Translated from Atomnaya énergiya, Vol. 106, No. 2, pp. 99–105, February, 2009.     

Radioecological studies of a construction site in Sayda Guba for long-term storage of reactor compartments

Specialists at the Russian Science Center Kurchatov Institute have performed radioecological studies on a construction site in Sayda Guba (Kol’skiy Zaliv) for long-term storage of reactor compartments. The results of these investigations are presented. Detailed investigations have shown that at the present time all radioecological parameters (γ-radiation dose rate on site, soil radon flux density, specific content of radionuclides in natural objects of plant and animal origin) fall within the natural background range. No technogenic anomalies have been found. __________ Translated from Atomnaya énergiya, Vol. 102, No. 3, pp. 276–281, March, 2007.     

乏燃料贮存格架的试制

简要介绍了乏燃料贮存格架实体模型试制过程中的生产准备、材料要求、关键零部件的加工、组焊、检验以及抽插试验的过程,为乏燃料贮存格架产品的制造和国产化提供了经验。     

Radioecological state of the territory and water area in Guba Andreev

The radioecological conditions which developed on the territory over the long operating time of the object of the naval fleet in Guba Andreev are described. The results of an analysis of the sources of the real and potential danger and measures to prevent dangerous effects for the environment and the workers at the time remediation work is performed are discussed. __________ Translated from Atomnaya énergiya, Vol. 101, No. 1, pp. 49–55, July, 2006.