Morimoto, Kyoichi; Kato, Masato; Komeno, Akira; Kashimura, Motoaki
Transactions of the American Nuclear Society, 97(1), p.618 - 619, 2007/11
Plutonium and uranium mixed oxide (MOX) fuel with high Pu-content has been developed as a fuel for fast reactors (FRs). Thermal conductivity of the oxide fuel is among the most important properties for design and performance analyses of fuel rods. Among recent reports, there have been none examining of thermal conductivity of MOX fuel containing Am except our studies. In this study, the thermal conductivities of MOX fuel with 30% Pu-content, as obtained by our group, were evaluated as functions of temperature, oxygen-to-metal (O/M) ratio and Am-content.
Komeno, Akira; Morimoto, Kyoichi; Kato, Masato; Kashimura, Motoaki; Ogasawara, Masahiro*; Sunaoshi, Takeo*
Transactions of the American Nuclear Society, 97(1), p.616 - 617, 2007/11
no abstracts in English
Katsuyama, Kozo; Nagamine, Tsuyoshi; Nakamura, Yasuo; Asaka, Takeo; Furuya, Hirotaka
Transactions of the American Nuclear Society, 97(1), p.620 - 621, 2007/11
no abstracts in English
Mosteller, R. D.*; Nagaya, Yasunobu
Transactions of the American Nuclear Society, 97(1), p.506 - 508, 2007/11
A suite of computational benchmarks for the Doppler reactivity defect has been recently approved by the Joint Benchmark Committee of the American Nuclear Society. The suite contains subsets of cases with weapons-grade MOX fuel, reactor-recycle MOX fuel, and UO fuel. The UO fuel contains enrichments up 5 wt.%, while the reactor-recycle and weapons-grade MOX fuel contain PuO at levels up to 8 wt.% and 6 wt.%, respectively. In this work, Monte Carlo calculations were performed with three major nuclear data libraries, JENDL-3.3 JEFF-3.1 and ENDF/B-VII.0. For the MOX problems, no differences were observed among Monte Carlo codes and nuclear data libraries, whereas the differences of about 10 % were observed between MCNP and MVP results at the lower enrichments for the UO problems. It is considered that the differences are not caused by the difference of the libraries but the instead by the scheme employed to generate the Monte Carlo cross section data at higher temperatures.
Sakaba, Nariaki; Hamamoto, Shimpei; Takeda, Yoichi*
Transactions of the American Nuclear Society, 97(1), p.678 - 680, 2007/11
Inherent safety advantages of the helium gas cooled reactors over other types of reactors depend importantly on the chemical stability of the actual helium coolant gas itself. Although helium being an inert gas does not react with fuel and components, chemical impurities which exist in the actual helium coolant can react with the surface of high-temperature materials such as the heat transfer tubes of the intermediate heat exchanger. The chemical effect of the impurities strongly influences to shorten the lifetime of the high-temperature materials. The dominant chemical reactions occurring in the core have not previously identified due to the complicated effects of not only high temperatures but also radioactivity during power operation of the helium gas cooled reactors. As such the methodology to control the high-temperature material lifetime has not been established because of the lack of knowledge and active control of the carbon activity and partial pressure of the oxygen which determine the creep fatigue of the high-temperature materials. The present study of the chemical equilibriums in the HTGR core is an initial effort to establish the lifetime extension methodology. The study examines the effects of high temperature and irradiation on the chemical equilibriums in the core by using an analytical code and basing on the chemical impurity data obtained in the HTTR operations.
Takeda, Yoichi*; Hamamoto, Shimpei; Sakaba, Nariaki
Transactions of the American Nuclear Society, 97(1), P. 677, 2007/11
Ni-base heat-resistant alloys are used for the structural components in gas cooled reactors and exposed to high-temperature helium gas environment. The degradation issues of the material like oxidation and creep are primary concern for the plant operation and further development of the alloys to be used in Very High-Temperature Reactor (VHTR) and Gas-Cooled Fast Reactor (GFR). In this investigation, corrosion testing facility was fabricated in order to investigate oxidation behavior of heat resistant alloys in high-temperature helium environments.
Misawa, Takeharu; Yoshida, Hiroyuki; Tamai, Hidesada; Takase, Kazuyuki
Transactions of the American Nuclear Society, 97(1), p.807 - 808, 2007/11