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[en] Mindful of possible future limitations on the availability of uranium, the introduction of the thorium fuel cycle is potentially a complementary source of nuclear energy. This publication assimilates current knowledge of thorium geology and mineralization into a brief account on the worldwide occurrence of thorium resources. Although thorium is currently not commercially viable as a fuel, it is important to pre-emptively assess thorium related information should that situation change. Thus, the publication provides an overview of the variety of natural thorium deposit types with associated thorium geology and thorium resources. It reviews available data on thorium occurrences/deposits and thorium resources and presents a classification of deposits according to geological and economic criteria.
[en] Existing NESs, which are mainly based on TRs operating in a once through cycle, will continue to represent the main contribution to nuclear energy production for at least several decades. As many national and international studies have shown, major innovations in reactor and NFC technologies are needed in order to achieve sustainable nuclear energy development. New reactors, nuclear fuels and fuel cycle technologies are under development and are being demonstrated worldwide. In these conditions, the evaluation of the status, prospects, benefits and risks associated with innovative technologies is very important. The results of such an evaluation could be useful not only for countries engaged in nuclear power development, but also for newcomer countries evaluating their potential to start a nuclear programme. This case study, performed by the team of Romanian experts from RATEN ICN Pitesti, proposes to apply the KIND approach to evaluate evolutionary and INES technologies comparatively, based on specific KIs. The analyses performed address the status, prospects, benefits and risks related to the development of these technologies, taking into consideration country specifics. The general and specific goals of the case study are in agreement with the KIND objectives.
[en] The Nuclear Fuel Cycle Simulation System (NFCSS) is a scenario based computer simulation tool that can model various nuclear fuel cycle options in various types of nuclear reactors. It is very efficient and accurate in answering questions such as: the nuclear mineral resources and technical infrastructure needed for the front end of the nuclear fuel cycle; the amounts of used fuel, actinide nuclides and high level waste generated for a given reactor fleet size; and the impact of introducing recycling of used fuel on mineral resource savings and waste minimization. Since the first publication on the NFCSS as IAEA-TECDOC-1535 in 2007, there have been significant improvements in the implementation of the NFCSS, including a new extension to thorium fuel cycles, methods to calculate decay heat and radiotoxicity, and demonstration applications to innovative reactors.
[en] This paper describes the status of the pre-conceptual design activities in Europe to advance the technical basis of the design of a DEMOnstration Fusion Power Plant (DEMO) to come in operation around the middle of this century with the main aims of demonstrating the production of few hundred MWs of net electricity, the feasibility of operation with a closed-tritium fuel cycle, and maintenance systems capable of achieving adequate plant availability. This is expected to benefit as much as possible from the ITER experience, in terms of design, licensing, and construction. Emphasis is on an integrated design approach, based on system engineering, which provides a clear path for urgent R and D and addresses the main design integration issues by taking account critical systems interdependencies and inherent uncertainties of important design assumptions (physics and technology). A design readiness evaluation, together with a technology maturation and down selection strategy are planned through structured and transparent Gate Reviews. By embedding industry experience in the design from the beginning it will ensure that early attention is given to technology readiness and industrial feasibility, costs, maintenance, power conversion, nuclear safety and licensing aspects. (paper)
[en] China NPPs Development Plan: Improving the utilization rate of uranium resources and disposing of spent fuel are two major problems in the development of nuclear energy. Developing fast reactors and their closed fuel cycles are important options for the sustainable development of nuclear energy in China.
[en] For an open or closed fuel cycle, the management of spent fuels is characterized by several phases until final storage. Between these phases, some operations have to be performed, such as conditionings, transports or recycling. For the safety, a global strategy for spent fuel management must be developed. This strategy is important to verify the consequences of choices made at one stage on the following stages, but also to define requirements of the parameters that will be used to justify the safety of the following stages and to anticipate knowledge needs. Furthermore, the strategy implantation requires significant time for the design, the licensing and the commissioning of facilities (typically more than 10 years for each facility). A strategy must be elaborated to give time for this process and for the dialogue with stakeholders. Finally, it’s important to check that the capacities of each stage are sufficient. Regarding safety, the facilities for spent fuel management use different processes with specific safety issues. Moreover, the designs of installations with the same objectives can be different. This diversity leads to produce a safety analysis for each installation. This analysis should be at least based on shared objectives and principles. The SSG-15 guide of IAEA is a good tool for this. This approach requires also particular safety skills for the operators, the safety authorities and their technical supports. These skills are varied, take time to be developed and must be maintained. Another aspect of the safety of such installations is that the analysis of severe accidents is less developed than for NPPs. The feedback of Fukushima accident shows the necessity to work on some severe accidents. In addition to the vigilance about the normal operating conditions of these facilities, this approach should be continued because it provides safety improvements. Other challenges are the ageing of these installations and how to improve their safety. Indeed, they will be operated during a very significant time and are generally complex to modify. Periodic safety reviews are a good mean to define improvements. In any case, the operating experience feedback should be shared. In this regard, the ability to monitor the safety functions and equipment is crucial. In the parts of installations where irradiated materials are handled, controls are difficult to be performed. This issue must be taken into account in the design and, for the older installations, require developments. (author)
[en] India has adopted closed fuel cycle to complete the three stage nuclear power programme envisaged by great founder and nuclear scientist, Homi J. Bhabha, which would provide energy security for the country. The spent fuel from Pressurised Heavy Water Reactors, the mainstay of nuclear power production in the country, are processed in reprocessing plants at Tarapur and Kalpakkam. In order to implement stage II of Indian NPP i.e. Fast Breeder Reactors (FBRs) are planned and fuel for these FBRs will be generated at large scale Integrated Recycle plants being set up for the first time. India has mastered the reprocessing and waste management technology indigenously for PHWR and FBR fuels and has been operating plants since last four decades. The large throughput plants are based on this technology incorporating improvements based on the feedback from the operating facilities taking into consideration of economics of construction and operation. This paper describes the details of Integration approach, spent fuel storage, processing and waste management being planned for large scale recycle plant. (author)
[en] Non-proliferation of nuclear materials and their losses within 0.1% level define the most important characteristics of ‘closed’ fuel cycle. The work is devoted to feasibility study of control the fissile nuclear materials via the differential die-away technique in case of high γ-background. Preliminary results obtained by the active neutron generator assembly showed that the minimal detectable mass of unshielded 235U in empty 70 l container is ~1 mg in case of 5x108 n/s neutron yield and 8 min duration of a measurement. (author)
[en] The current growth of the energy demand, the perspective of a pronounced increment for the next decades, added to the near depletion of the fossil fuels has made necessary finding a sustainable energy supply. Nuclear energy is presented as an important energy source to meet global energy needs in the near future, without adverse impacts to the environment. However, it faces substantial challenges to be successful as sustainable energy source. Pebble Bed Very High Temperature advanced systems together with fuel cycles based in Thorium present significant perspectives to assume the future nuclear energy. In this paper the main advantages of the use a Generation IV Very High Temperature Hybrid System (VHTHS) using a variety of fuel cycles based on Thorium (232Th-233U, 232Th-239Pu and 232Th-U) under a deep burn scheme are studied. The conceptual design of the VHTHS composed of a Very High Temperature Pebble Bed Reactor (VHTR) and two Pebble Bed Accelerator Driven Systems (ADSs) is analyzed. Parameters such as the isotopic composition, the Minor Actinides stockpile, the nuclear fuel breeding, the percent fissile fuel and the radiotoxicity of the long-lived wastes are determined in order to know the influence of using Thorium based fuel cycles and ADSs as a second stage in the VHTHS. The MCNPX version 2.6e was used for the neutronic calculations. (author)
[en] Thorium represents a valuable fuel alternative to uranium, but since it has no fissile isotopes, it is necessary to foresee using a small amount of fissile material to initiate the chain reaction. Many studies (related to reactor physics and fuel performance) have been performed worldwide for Th+U, Th+Pu and even Th+Minor Actinides. In Romania, given the safeguard limitations, the only considered fissile material is U-235. The thorium fuel cycles in CANDU nuclear reactors maintain their strategic interest as they ensure a long-term resources availability, especially for those countries possessing large thorium reserves but limited uranium resources. Again, driven by safeguard limitations, the ‘once-through’ thorium cycle without reprocessing was taken into account. This report reviews the analytical and experimental work performed at Institute of Nuclear Reactor (INR) concerning the nuclear fuel containing mixed oxide of thorium and uranium to be used in existing CANDU reactors. A major request was that the CANDU power plant design, especially the reactor core design, should not be modified in order to comply with using the advanced fuel bundles, excepting for the fuel bundle itself. Based on previous studies performed in Canada, China, India and Korea, the fuel bundle considered for hosting mixed oxide of thorium and uranium would be T43, a 43 elements bundle.