[en] Recently, efforts to develop high temperature gas cooled reactors with an aim to building futuristic nuclear energy systems with advanced nuclear fuel cycles in the context of the Generation IV International Forum have increased significantly. In addition, several development projects are ongoing, focusing on the burning of weapons grade plutonium, including civil plutonium and other transuranic elements using the 'deep-burn concept', or 'inert matrix fuels', especially in the form of coated particles in gas cooled reactor systems. There is also considerable global interest in developing 'nuclear hydrogen' energy systems using high temperature gas cooled reactors. Apart from these developments, the value of preserving the large technology base developed in Germany, the United Kingdom and the United States of America, as well as information developed in other countries, has also been a subject of interest to the IAEA. At the second annual meeting of the 'technical working group on nuclear fuel cycles options and spent fuel management' (TWG-NFCO), held in Vienna from 28-30 May 2003, it was recommended to hold a technical meeting on Current Status and Future Prospects of Gas Cooled Reactor Fuels. The meeting should cover the technological progress that has been made in the last three years and plan future fabrication and qualification facilities for GCR/HTR fuel. TWG-NFCO considered it timely that this progress should be presented and discussed in the interested community. Recognizing the numerous activities being pursued in many Member States, the IAEA convened the technical meeting on this topic in June 2004 in Vienna. Consequently, an update meeting was held in June 2005, which was hosted by the Kharkov Institute of Physics and Technology of Ukraine to review and integrate the latest developments. This publication combines the results of the technical meeting of June 2004 and the meeting of June 2005. The proceedings presented here contain 25 in depth papers on the following topics: overview of recent developments in nine countries; power and limitations of coated particle fuel modelling; Fuel performance technology; and novel ideas/applications/disposal questions. The meeting critically reviewed advanced fuel designs, including conventional ones, fabrication technology, quality assurance/quality control of fuel, fuel irradiation qualification, fuel performance, fuel modelling for transport and performance and overall fuel cycle issues

[en] A short information on Russian investigations in the field of tri-isotropic (TRISO) coated particle fuels development for high temperature reactor system (HTR) with pebble bed core (VGR - 50, VG - 400, VGM reactors) is presented. Requirements for UO₂ kernels with a 500 μm diameter and for coatings on them as well as the achieved characteristics of coated particle fuels are discussed. In the report requirements for coated particle fuels on the base of kernels of 200 μm in diameter for Modular High-Temperature Gas-cooled Reactor (MHTGR) with a prismatic core are also described. The first results of investigations on manufacture of such coated particle fuels in the laboratory scale are given. (author)

[en] We have investigated the waste actinide burnup capabilities of the gas turbine modular helium reactor (GT-MHR), similar to the reactor being designed by General Atomics and Minatom for surplus weapons plutonium destruction) with the Monte Carlo continuous energy burnup code (MCB), an extension of Monte Carlo N-particle transport code (MCNP) developed at the Royal Institute of Technology in Stockholm and the University of Science and Technology in Cracow. The GT-MHR is a gas-cooled, graphite-moderated reactor, which can be powered with a wide variety of fuels, like thorium, uranium or plutonium. In the present studies, the GT-MHR is fueled with the transuranic actinides contained in light water reactors (LWRs) spent fuel for the purpose of destroying them as completely as possible. The driver fuel (DF) of the GT-MHR uses fissile isotopes (e.g. ²³⁹Pu and ²⁴¹Pu), previously generated in the LWRs, and maintains criticality conditions in the GT-MHR. After an irradiation of three years, the spent driver fuel is reprocessed and its remaining actinides are manufactured into fresh transmutation fuel (TF). Transmutation Fuel mainly contains non-fissile actinides that undergo neutron capture and transmutation during the subsequent three-year irradiation in the GT-MHR. At the same time, TF provides control and negative reactivity feedback to the reactor. The destruction of more than 94% of ²³⁹Pu and the other geologically problematic actinide species makes this reactor a valid proposal for the reduction of nuclear waste and the prevention of proliferation. (author)

[en] The National Nuclear Energy Agency of Indonesia (Batan) has appointed a team for development of high temperature gas cooled reactor (HTGR) in 1993 to conduct studies on high termperature reactor (HTR) technology and its application. The team was initially divided into two groups including reactor technology, safety and applications. R and D on nuclear fuel have been started in 1980s. Significant achievement has been conducted in mastering U₃Si₂ fuel technology in order to self - supply of plate type fuel for 30 MW RSG - GAS reactor. The work was conducted with the assistance of the IAEA through a technical assistance program starting in 1989 and ceased in 1995. Under the IAEA's technical assistance program came a German and several US experts providing direct assistance and supervision. The program had successfully brought Indonesia a capability to produce U₃Si₂ fuel elements and ultimately insert some U₃Si₂ fuel elements in 1991, which then were subjected to successful post - irradiation examinations three years later. The HTR program was subsequently expanded in 1997 into five general areas of HTGR development including reactor technology, optimization of electricity, steam co - generation, safety, environmental, coal liquefaction, desalination, instrumentation, control the HTR fuel cycle. Unfortunately monetary crisis, gives impact on R and D activity including the HTR fuel program. The paper present Batan activities during six years. The experimental study has been performed in fuel kernel fabrication, design of fluidized bed experimental reactor, and some fuel performance modeling. Other activities are bibliographic studies in fluidized bed reaction for kernel coating, safety analysis of component reactor failure, and recovery of fuel from GCR - spent fuel. (author)

[en] High temperature gas-cooled reactor (HTGR) is recognized as an advanced type of reactor with its inherent safety feature, fuel cycle flexibility, high fuel utilization, high efficient electricity generation and process heat application. The fuel element of the HTGR is all-ceramic type, and is crucial for the safety and reliable operation of the HTGR. Therefore, R and D activities for HTGR and its fuel element started from the middle of 1970's in China, and have begun to be a part of China high technology program since 1986. R and D work of HTGR fuel element was carried out in experimental scale before 1991. Since 1991 R and D activities have been focused on fabrication technology for Chinese 10 MW high temperature gas-cooled reactor (HTR-10) first core fuel. During long-term R and D activities, Institute of Nuclear Energy Technology, Tsinghua University (INET) has successfully developed own fabrication technologies of spherical fuel elements for HTR-10. Over 20 000 spherical fuel elements have been fabricated in 2000 and 2001. The performance of the fabricated fuel elements meets the design requirement of HTR-10 fuel. (author)

[en] Advanced gas cooled reactor systems for future combined cycle applications (electricity and process heat) are planned to operate at temperatures up to or even above 1000 ^oC. The reliable and safe operation of such plants requires materials that are able to carry loads at these temperatures in impure helium and under neutron irradiation. The most exposed components are the pressure vessel, reactor internals, gas turbine, pipes and valves. Considering the envisaged long operating time (6 years for replaceable components) life time assessments and extrapolation methods are necessary for the determination of damage evolution and long term behaviour of the reactor components. This paper gives a summary of candidate materials and possible approaches to life-time assessment. The paper concentrates mainly on very high temperature reactors (VHTR), some material aspects of gas cooled fast reactors (GFR) are considered, too. (author)

[en] The high temperature engineering test reactor (HTTR) achieved the reactor outlet coolant temperature of 950 ^oC on April 19, 2004. Research and developments of the high temperature gas-cooled reactor (HTGR) that has merits of supplying high temperature heat, inherent safety features, high thermal efficiency, high burnup of fuel, and so on are particularly important for diversification of energy supply in the future. In addition, progress of innovative basic research is expected by utilizing capacity of the HTGR for irradiation of large-scale test specimens under high temperature conditions. In this paper, we describe present status of operation and tests of the HTTR, and research on nuclear heat application. (author)

[en] In the French HTR programme, CEA and AREVA/Framatome (now called as AREVA NP) conduct research and development on HTR fuel aiming in mastering the UO₂ Triso particle fuel fabrications technology, irradiating new fuels coming from the new French facilities, performing post-irradiation examinations on these fuels and developing codes predicting fuel performance and fission product transport. (author)

[en] A key part of the IAEA 6th Coordinated Research Project on advances in high temperature reactor (HTR) fuel technology includes benchmarking of fuel performance models under normal and accident conditions. The normal operation and accident behaviour benchmarks have been structured in two phases. In the first phase, a series of simplified analytical benchmarking problems have been established for both normal and accident conditions as a way to 'calibrate' all of the codes and/or models. In the second phase, the codes and/or models will be used to calculate fuel behaviour in past and future irradiation experiments and heating tests. Current participants in the benchmark include England, France, Germany, Russia and the United States. This paper will present a status of this international code benchmarking activity. (author)

[en] In anticipation of future licensing applications for gas-cooled reactors, the United States Nuclear Regulatory Commission (NRC) seeks to fully understand the significant features of TRISO-coated particle fuel design, manufacture, and operation, as well as behaviour during accidents. To address this objective, the NRC commissioned the formation of a panel of experts to identify and rank the factors, characteristics, and phenomena associated with the life-cycle phases of TRISO-coated particle fuel. Six phenomena identification and ranking tables were developed by the panel and are presented in this report. They are: (1) Manufacturing, (2) Operations, (3) Depressurized Heatup Accident, (4) Reactivity Accident, (5) Depressurization Accident with Water Ingress, and (6) Depressurization Accident with Air Ingress. Analyses and summaries for each of the six 'phenomena identification and ranking tables' (PIRTs) are presented in the panel's report. A total of 327 factors, characteristics and phenomena are identified in the six PIRT tables. The importance of each factor, characteristic, process or phenomenon was assessed relative to the magnitude of its influence on fission product release or in a more accident consequence-related term, the source term. One hundred-ten factors, characteristics and phenomena were assigned an importance rank of 'High' by each panel member. The panel concluded that these 110 factors, characteristics and phenomena had the most significant impact on fission product release. Each panel member prepared a written rationale supporting the importance rank assigned to each highly ranked factor, characteristic or phenomenon. These rationales are included. The level of knowledge for each factor, characteristic or phenomenon was also assessed and documented. Of particular interest are those factors, characteristics or phenomena assessed by the panel as being of high importance but not yet adequately understood. The PIRT results will be used by the agency to: (1) identify key attributes of gas-cooled reactor fuel manufacture which may require regulatory oversight; (2) provide a valuable reference for the review of vendor gas-cooled reactor fuel qualification plans (3) provide insights for developing plans for fuel safety margin testing; (4) assist in defining test data needs for the development of fuel performance and fission product transport models (5) inform decisions regarding the development of NRC's independent gas-cooled reactor fuel performance code and fission product transport models; (6) support the development of NRC's independent models for source term calculations; and (7) provide insights for the review of vendor gas-cooled fuel safety analyses. (author)