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Journal Articles

Fuel performance evaluation of rock-like oxide fuels

Shirasu, Noriko; Kuramoto, Kenichi; Nakano, Yoshihiro; Yamashita, Toshiyuki; Kimura, Yasuhiko; Nihei, Yasuo; Ogawa, Toru

Journal of Nuclear Materials, 376(1), p.88 - 97, 2008/05

 Times Cited Count:13 Percentile:68.01(Materials Science, Multidisciplinary)

The concept of the rock-like oxide (ROX) fuel has been developed for the annihilation of excess plutonium in light water reactors. Irradiation tests and post-irradiation examinations were carried out on candidate ROX fuels. The ternary fuel of YSZ-spinel-corundum system, the single-phase fuels of YSZ, the particle dispersed fuels of YSZ in spinel or corundum matrix, and the blended fuels of YSZ and spinel or corundum matrix were fabricated and submitted to irradiation tests. The fuels containing spinel showed chemical instabilities with the vaporization of MgO component, which caused fuel restructuring. The swelling behavior was improved with the particle-dispersed fuels. However, the particle-dispersed fuels showed higher fractional gas release (FGR) than blended type fuels. The FGR of YSZ single-phase fuels were comparable to what would be expected for UO$$_{2}$$ fuels. The YSZ single-phase fuel showed the best irradiation performance among the ROX fuels investigated.

Journal Articles

Study of rock-like oxide fuels under irradiation

Shirasu, Noriko; Kuramoto, Kenichi; Nakano, Yoshihiro; Yamashita, Toshiyuki; Ogawa, Toru

Journal of Power and Energy Systems (Internet), 2(1), p.145 - 152, 2008/00

To evaluate the irradiation behavior of the rock-like oxide fuel, irradiation experiments were carried out. Three fuels were prepared; a single phase fuel of yttria-stabilized zirconia containing UO$$_{2}$$ (U-YSZ) and two types of particle-dispersed fuels of U-YSZ particles in spinel or corundum matrix. These fuels were irradiated in JRR-3 for about 280 days. The burnups were about 11% FIMA. The fission gas release rate (FGR) was determined by puncture test and gas analysis. Corundum-based fuel showed extremely high FGR (88%). The temperature of U-YSZ single-phase fuel pellets was highest among the fuels, because of its low thermal conductivity. Nevertheless the U-YSZ single-phase fuel showed very low FGR (5%). Microstructure analyses of irradiated fuel pellets were carried out by ceramography and EPMA. The restructuring of fuel pellet was not observed in the spinel-based fuel irradiated below 1400 K.

Journal Articles

Study of rock-like oxide fuels under irradiation

Shirasu, Noriko; Kuramoto, Kenichi; Nakano, Yoshihiro; Yamashita, Toshiyuki; Ogawa, Toru

Proceedings of 15th International Conference on Nuclear Engineering (ICONE-15) (CD-ROM), 7 Pages, 2007/04

To evaluate the irradiation behavior of the rock-like oxide fuel, irradiation experiments were carried out. Three fuels were prepared; a single phase fuel of yttria-stabilized zirconia containing UO$$_{2}$$ (U-YSZ) and two particle-dispersed fuels of U-YSZ particles in spinel or corundum matrix. These fuels were irradiated in JRR-3 for about 280 days. The burnups were about 11% FIMA. The fission gas release rate (FGR) was determined by puncture test and gas analysis. Corundum-based fuel showed extremely high FGR (88%). On the other hand, the U-YSZ single-phase fuel showed very low FGR (5%). Microstructure analyses for irradiated fuel pellets were carried out by ceramography and EPMA. The restructuring of fuel pellet was not observed in the spinel-based fuel irradiated below 1400 K. Significant appearance changes were not also observed for corundum-based fuel.

Journal Articles

Post-irradiation examination on particle dispersed rock-like oxide fuel

Shirasu, Noriko; Kuramoto, Kenichi*; Yamashita, Toshiyuki; Ichise, Kenichi; Ono, Katsuto; Nihei, Yasuo

Journal of Nuclear Materials, 352(1-3), p.365 - 371, 2006/06

 Times Cited Count:4 Percentile:32.55(Materials Science, Multidisciplinary)

To evaluate irradiation behavior of the ROX fuel, irradiation experiment was carried out using 20% enriched U instead of Pu. Three fuels were prepared; a single phase fuel of YSZ containing UO$$_{2}$$ (U-YSZ), two particle-dispersed fuels of U-YSZ particle in spinel or corundum matrix. The U-YSZ particles were prepared by crashing presintered U-YSZ pellets and by sieving them. These fuels were irradiated in Japan Research Reactor No.3 for 13 cycles, about 300 days. Though many cracks were observed in the pellets by X-ray photographs, significant appearance changes were not observed for all fuel pins. Distribution of typical FPs was analyzed by the $$gamma$$ scanning over the fuel pin. Non-volatile nuclide remained in the fuel pellet. On the other hand, a part of Cs moved to the gaps between the pellets and to the insulators. $$^{134}$$Cs and $$^{137}$$Cs showed different distributions at the plenum. Fuel pellets were taken out from fuel pins without bonding. Spinel decomposition and subsequent restructuring were not observed probably due to low irradiation temperature.

Journal Articles

Irradiation behavior of rock-like oxide fuels

Yamashita, Toshiyuki; Kuramoto, Kenichi; Shirasu, Noriko; Nakano, Yoshihiro; Akie, Hiroshi; Nagashima, Hisao; Kimura, Yasuhiko; Omichi, Toshihiko*

Journal of Nuclear Materials, 320(1-2), p.126 - 132, 2003/07

 Times Cited Count:10 Percentile:58.26(Materials Science, Multidisciplinary)

Two irradiation tests on the rock-like oxide (ROX) fuels, small disk-shape fuel targets and pellet-type fuels, were performed in order to clarify in-pile irradiation stabilities. Swelling, fractional fission gas release (FGR) and phase change were examined by puncture test, profilometry and ceramography. YSZ single-phase fuel showed an excellent irradiation behavior, ie. low fission gas release (less than 3%), negligible swelling and no appreciable restructuring. The particle dispersed fuels showed lower swelling and higher fission gas release than those of mechanically blended fuels. Spinel decomposition and subsequence restructuring in the spinel matrix fuels was observed for the first time in the present investigation. It would be possible to reduce the FGR of the spinel matrix fuels, if the maximum fuels temperature is limited below 1700 K where neither spinel decomposition nor restructuring was observed. Damaged area of spinel matrix due to fission fragment irradiation seemed to be confined to thin layers around the surface of YSZ particles.

Journal Articles

Durability test of irradiated rock-like oxide fuels

Kuramoto, Kenichi; Shirasu, Noriko; Yamashita, Toshiyuki

Journal of Nuclear Materials, 319(1-3), p.180 - 187, 2003/06

 Times Cited Count:8 Percentile:51.59(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Phase relations between a fluorite and a pyrochlore structure in the system of actinides and zirconium oxides

Yamashita, Toshiyuki; Kuramoto, Kenichi; Nakada, Masami; Yamazaki, Satoshi*; Sato, Tsuyoshi*; Matsui, Tsuneo*

Journal of Nuclear Science and Technology, 39(Suppl.3), p.585 - 591, 2002/11

no abstracts in English

Journal Articles

Rock-like oxide fuels and their burning in LWRs

Yamashita, Toshiyuki; Kuramoto, Kenichi; Akie, Hiroshi; Nakano, Yoshihiro; Shirasu, Noriko; Nakamura, Takehiko; Kusagaya, Kazuyuki*; Omichi, Toshihiko*

Journal of Nuclear Science and Technology, 39(8), p.865 - 871, 2002/08

 Times Cited Count:25 Percentile:83.26(Nuclear Science & Technology)

Research on the plutonium rock-like oxide (ROX) fuels and their once-through burning in light water reactors has been performed to establish an option for utilizing and disposing effectively the excess plutonium. The ROX fuel is a sort of the inert matrix fuels and consists of mineral-like compounds such as yttria stabilized zirconia, spinel and corundum. A particle-dispersed fuel was devised to reduce damage by heavy fission fragments. Some preliminary results on swelling, fractional gas release and microstructure change for five ROX fuels were obtained from the irradiation test and successive post-irradiation examinations. Inherent disadvantages of the Pu-ROX fuel cores could be improved by adding 238U or 232Th as resonant materials, and all improved cores showed a nearly the same characteristics as the conventional UO2 core during transient conditions. The threshold enthalpy of the ROX fuel rod failure was found to be comparable to the fresh UO2 rod by pulse-irradiation tests simulating reactivity initiated accident conditions.

Journal Articles

Post-irradiation examination of uranium-based rock-like oxide fuels

Kuramoto, Kenichi; Yamashita, Toshiyuki; Shiratori, Tetsuo

Progress in Nuclear Energy, 38(3-4), p.423 - 426, 2001/02

 Times Cited Count:6 Percentile:45.58(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Current status of researches on the plutonium rock-like oxide fuel and its burning in light water reactors

Yamashita, Toshiyuki; Akie, Hiroshi; Nakano, Yoshihiro; Kuramoto, Kenichi; Nitani, Noriko; Nakamura, Takehiko

Progress in Nuclear Energy, 38(3-4), p.327 - 330, 2001/02

 Times Cited Count:12 Percentile:66.3(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Re-evaluation of the phase relationship between plutonium and zirconium dioxides

Serizawa, Hiroyuki; Nakajima, Kunihisa; Arai, Yasuo; Yamashita, Toshiyuki; Kuramoto, Kenichi; Kinoshita, H.*; Yamanaka, Shinsuke*; Uno, Masayoshi*; Kurosaki, K.*

Progress in Nuclear Energy, 38(3-4), p.237 - 240, 2001/02

 Times Cited Count:5 Percentile:40.34(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Evaluation on chemical state of irradiated rock-like oxide fuels by nuclear and chemical modeling

Nitani, Noriko; Kuramoto, Kenichi; Yamashita, Toshiyuki; Omichi, Toshihiko*

Progress in Nuclear Energy, 38(3-4), p.435 - 438, 2001/02

 Times Cited Count:1 Percentile:12.49(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Rock-like oxide fuels for burning excess plutonium in LWRs

Yamashita, Toshiyuki; Kuramoto, Kenichi; Akie, Hiroshi; Nakano, Yoshihiro; Nitani, Noriko; Nakamura, Takehiko; Kusagaya, Kazuyuki*; Omichi, Toshihiko*

Proceedings of Workshop on Advanced Reactors with Innovative Fuels (ARWIF 2001) (CD-ROM), 10 Pages, 2001/00

no abstracts in English

Oral presentation

Post irradiation examination on particle dispersed Uranium Rock-like Oxide (U-ROX) fuel, 3; Ceramographic examination

Shirasu, Noriko; Kuramoto, Kenichi*; Yamashita, Toshiyuki; Honda, Junichi; Hatakeyama, Yuichi; Ichise, Kenichi

no journal, , 

no abstracts in English

Oral presentation

Activity of Am and Ce in liquid gallium

Hayashi, Hirokazu; Kuramoto, Kenichi*; Akabori, Mitsuo; Arai, Yasuo

no journal, , 

no abstracts in English

15 (Records 1-15 displayed on this page)
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