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Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.
Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09
Times Cited Count：5 Percentile：87.42(Nuclear Science & Technology)In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.
Uwaba, Tomoyuki; Nemoto, Junichi*; Ito, Masahiro*; Ishitani, Ikuo*; Doda, Norihiro; Tanaka, Masaaki; Otsuka, Satoshi
Nuclear Technology, 207(8), p.1280 - 1289, 2021/08
Times Cited Count：3 Percentile：34.82(Nuclear Science & Technology)Computer codes for irradiation behavior analysis of a fuel pin and a fuel pin bundle and for coolant thermal hydraulics analysis were coupled into an integrated code system. In the system, each code provides data required by other codes and the analyzed results are shared among them. The system allows for the synthesizing of analyses of thermal, chemical and mechanical behaviors in a fuel subassembly under irradiation. A test analysis was made for a fuel subassembly containing a mixed oxide fuel pin bundle irradiated in a fast reactor. The results of the analysis were presented with transverse cross-sectional images of the fuel subassembly and three-dimensional images of a fuel pin and fuel pin bundle models. For detailed evaluation, various irradiation behaviors of all fuel pins in the subassembly were analyzed and correlated with irradiation conditions.
Uwaba, Tomoyuki; Yokoyama, Keisuke; Nemoto, Junichi*; Ishitani, Ikuo*; Ito, Masahiro*; Pelletier, M.*
Nuclear Engineering and Design, 359, p.110448_1 - 110448_7, 2020/04
Times Cited Count：1 Percentile：11.8(Nuclear Science & Technology)Coupled computer code analyses of irradiation performance of axially heterogeneous mixed oxide (MOX) fuel elements with high burnup in a fast reactor were conducted. Post-irradiation experiments revealed local concentration of Cs near the interfaces between MOX fuel and blanket columns including the internal blanket of the fuel elements as well as an increase in their cladding diameters. The analyses indicated that the local Cs concentration occurred as a result of Cs axial migration from the MOX fuels toward the blanket pellets near the interfaces. Swelling of the blanket pellets induced by the formation of low-density Cs-U-O compound was not sufficient to cause pellet-to-cladding mechanical interaction (PCMI). The PCMI analyzed in the MOX fuel column regions was insignificant, and the cladding diameter increases were caused mainly by void swelling in cladding and irradiation creep due to fission gas pressure.
Uwaba, Tomoyuki; Nemoto, Junichi*; Ishitani, Ikuo*; Ito, Masahiro*
Nuclear Engineering and Design, 331, p.186 - 193, 2018/05
Times Cited Count：4 Percentile：38.11(Nuclear Science & Technology)A computer code for the analysis of the overall irradiation performance of a fast reactor mixed-oxide (MOX) fuel element was coupled with a specialized code for the analysis of fission product cesium behaviors in a MOX fuel element. The coupled code system allowed for the analysis of the radial and axial Cs migrations, the generation of Cs chemical compounds and fuel swelling due to Cs-fuel-reactions in association with the thermal and mechanical behaviors of the fuel element. The coupled code analysis was applied to the irradiation performance of a fast reactor MOX fuel element attaining high burnup for discussion on the axial distribution of Cs, fuel-to-cladding mechanical interaction owing to the Cs-fuel-reactions by comparing the calculated results with post irradiation examinations.
Ino, Kohei*; Hernsdorf, A. W.*; Konno, Yuta*; Kozuka, Mariko*; Yanagawa, Katsunori*; Kato, Shingo*; Sunamura, Michinari*; Hirota, Akinari*; Togo, Yoko*; Ito, Kazumasa*; et al.
ISME Journal, 12(1), p.31 - 47, 2018/01
Times Cited Count：49 Percentile：91.37(Ecology)In this study, we found the dominance ofanaerobic methane-oxidizing archaea in groundwater enriched in sulfate and methane from a 300-m deep underground borehole in granitic rock.
Ito, Takashi; Morishita, Takatoshi; Tamura, Jun; Nammo, Kesao*; Sugimura, Takashi*
Proceedings of 8th International Particle Accelerator Conference (IPAC '17) (Internet), p.4184 - 4186, 2017/06
We have suffered from multipactor problem of some SDTLs after the Great East Japan Earthquake. As a designed operating rf power of the SDTL is in the multipactor region, we had to operate at higher power of the designed one. From the result of the simulation and the observation of the SDTL cavity, it became clear that the multipactor occurred on the inner surface of the cavity. We think that one of the cause of the multifactor is the contamination on the inner surface of the cavity, we performed the cleaning of the inner surface of the cavity by using acetone. The cleaning was very effective and the multipactor region was reduced or disappeared. The multipactor problem has not occurred since then.
Ino, Kohei*; Konno, Yuta*; Kozuka, Mariko*; Hirota, Akinari*; Togo, Yoko*; Fukuda, Akari*; Komatsu, Daisuke*; Tsunogai, Urumu*; Tanabe, Akifumi*; Yamamoto, Satoshi*; et al.
Environmental Microbiology Reports (Internet), 8(2), p.285 - 294, 2016/04
Times Cited Count：26 Percentile：68.23(Environmental Sciences)To understand the subsurface biosphere, borehole investigation was conducted for 300-m deep granitic rocks at the Mizunami underground research laboratory, Japan. The initial biomass was the highest with the flourish of aerobic H
-oxidizing Hydrogenophaga spp., whereas an uncultivated lineage of the phylum Nitrospirae became predominant after three years with decreasing biomass. The common occurrence of many species of Nitrospirae and Chlorobi phyla at the geographically distinct sites and the exclusive detection of their phylogenetically related environmental sequences from deep groundwaters and terrestrial hot springs, suggest that these bacteria are indigenous and potentially adapted to the deep terrestrial subsurface.
Nemoto, Yasuo; Tamura, Jun; Ito, Takashi; Morishita, Takatoshi; Hirano, Koichiro; Kondo, Yasuhiro; Oguri, Hidetomo; Sugimura, Takashi*; Nammo, Kesao*; Ao, Hiroyuki*
Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1101 - 1104, 2015/09
In J-PARC linac, ACS (Annular-ring Coupled Structure) has been operating for one and a half years. Through the long term operation, the ACS cavities have been well conditioned. Therefore, the vacuum pressure of the ACS was reduced to 1
10
Pa, which is much lower than the required value, and RF trip rate was steadily decreased. At present, the ACS continues to be stably operating without sacrificing the operating time of the J-PARC accelerator complex. The vacuum leaks caused by the generated crack in the aluminum chain clamps in the ACS beam line have happened five times in the past. To prevent the same situation from occurring, we replaced all the aluminum clamps to the stainless steel clamps. The residual radiation between each ACS cavity is considerably high. It is considered that the CT monitors, which have smaller aperture than that of other instruments in the beam line, contributes to the residual radiation. We are trying to reduce the residual radiation by enlarging the monitor's aperture and by replacing the unused monitors to the titanium ducts in this summer shutdown period.
Uwaba, Tomoyuki; Mizuno, Tomoyasu; Nemoto, Junichi*; Ishitani, Ikuo*; Ito, Masahiro*
Nuclear Engineering and Design, 280, p.27 - 36, 2014/12
Times Cited Count：11 Percentile：64.35(Nuclear Science & Technology)A deterministic computer code CEDAR has been developed to analyze irradiation behaviors of a mixed-oxide fuel pellet pin in a FBR. The FEM was incorporated into the mechanical calculation part of the code for properly analyzing stress-strain status in the fuel pellet and cladding, and mechanical interaction between the fuel pellet and cladding. The code features mechanistic analyses of irradiation behaviors of a fuel pin by integrating a lot of models to analyze major irradiation phenomena, thus expressing actual fuel pin irradiation behaviors. Analysis capabilities of the code were validated by calculations of fuel pellet temperatures, fractional fission gas releases of fuel pins and fuel pin cladding diametral strain profiles. The mechanisms of the fuel pin irradiation behaviors such as redistribution of Americium, PCMI and JOG formation were interpreted from the code analyses for the actual irradiation test fuel pins.
Suzuki, Yohei*; Konno, Yuta*; Fukuda, Akari*; Komatsu, Daisuke*; Hirota, Akinari*; Watanabe, Katsuaki*; Togo, Yoko*; Morikawa, Noritoshi*; Hagiwara, Hiroki; Aosai, Daisuke*; et al.
PLOS ONE (Internet), 9(12), p.e113063_1 - e113063_20, 2014/12
Times Cited Count：12 Percentile：36.57(Multidisciplinary Sciences)We present multi-isotopic evidence of microbially mediated sulfate reduction in a granitic aquifer, a representative of the terrestrial crust habitat. Deep groundwater of meteoric origin was collected from underground boreholes drilled into the Cretaceous Toki granite, central Japan. A large sulfur isotopic fractionation of 20-60 permil diagnostic to microbial sulfate reduction is associated with the investigated groundwater containing sulfate below 0.2 mM. In contrast, a small carbon isotopic fractionation (
30 permil) is not indicative of methanogenesis. Our results demonstrate that the deep biosphere in the terrestrial crust is metabolically active and playing a crucial role in the formation of reducing groundwater even under low energy fluxes.
Oguri, Hidetomo; Hasegawa, Kazuo; Ito, Takashi; Chishiro, Etsuji; Hirano, Koichiro; Morishita, Takatoshi; Shinozaki, Shinichi; Ao, Hiroyuki; Okoshi, Kiyonori; Kondo, Yasuhiro; et al.
Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.389 - 393, 2014/10
no abstracts in English
Uwaba, Tomoyuki; Ito, Masahiro*; Nemoto, Junichi*; Ichikawa, Shoichi; Katsuyama, Kozo
Journal of Nuclear Materials, 452(1-3), p.552 - 556, 2014/09
Times Cited Count：1 Percentile：8.82(Materials Science, Multidisciplinary)The BAMBOO code was verified by results for the out-of-pile bundle compression test with large diameter pin bundle deformation under the bundle-duct interaction (BDI) condition. The pin diameters of were 8.5 mm and 10.4 mm, which are targeted as preliminary fuel pin diameters for the upgraded core of the prototype FBR and for demonstration and commercial FBRs studied in the FaCT project. In the bundle compression test, bundle cross-sectional views were obtained from X-ray computer tomography (CT)images and local parameters of bundle deformation were measured by CT image analyses. In the verification, calculation results of bundle deformation obtained by the BAMBOO code analyses were compared with the experimental results from the CT image analyses. The comparison showed that the BAMBOO code reasonably predicts deformation of large diameter pin bundles under the BDI condition by assuming that pin bowing and cladding oval distortion are the major deformation mechanisms.
Miura, Akihiko; Miyao, Tomoaki*; Ito, Takashi; Hirano, Koichiro; Nammo, Kesao*; Maruta, Tomofumi; Tamura, Jun; Ikegami, Masanori*; Naito, Fujio*
Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.653 - 655, 2013/08
The beam operation of J-PARC linac was suspended until December 2011 due to the damage by the Tohoku earthquake in March 2011. After resumed the operations, we measured the residual radiation along with the beam line during a short interval. Because the higher residual radiation was detected at the surface of drift tube linac (DTL) cavity by radiation survey, we installed the scintillation beam loss monitors (BLM) at the points where the higher radiation was detected to understand the cause of the radiation. Even the DTL section is low energy part of the linac, fine structure of the beam loss was observed by the scintillation BLM. And we measured the beam loss occurred at the DTL with the parameters of beam orbit and cavity settings. Also, the BLM is employed for the linac tuning. In this paper, the result of the radiation measurement and beam loss signals obtained by the scintillation BLMs are presented.
Yamaguchi, Akira*; Tatsumi, Eisaku*; Takata, Takashi*; Ito, Kei; Ohshima, Hiroyuki; Kamide, Hideki; Sakakibara, Jun*
Nuclear Engineering and Design, 241(5), p.1627 - 1635, 2011/05
Times Cited Count：6 Percentile：44.16(Nuclear Science & Technology)In a sodium-cooled fast reactor, inert gases exist in the primary coolant system either in a state of dissolved gas or free gas bubbles. In the present study, a gas entrainment allowance level at the free surface is discussed and rationalized. The influence of the gas entrainment is evaluated using the void fraction at the core inlet. For the purpose, a plant dynamics code VIBUL has been developed to evaluate the concentration distribution of the dissolved gas and the free gas bubble. It is noted that the background level is already very low in comparison with the induced void reactivity by the void passing the reactor core.
Yamaguchi, Akira*; Takata, Takashi*; Tatsumi, Eisaku*; Ito, Kei; Ohshima, Hiroyuki; Kamide, Hideki; Sakakibara, Jun*
Proceedings of 7th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operation and Safety (NUTHOS-7) (CD-ROM), 16 Pages, 2008/10
In a sodium-cooled fast reactor, inert gases exist in the primary coolant system either in a state of dissolved gas or free gas bubbles. The gas in the primary system may cause disturbance in reactivity, nucleation site for boiling, etc. Therefore, the allowance level is necessary regarding the gas entrainment and the gas bubble concentration. In the present study, a gas entrainment allowance level is discussed and rationalized. For the purpose, a plant dynamics code VIBUL has been developed to evaluate the concentration distribution of the dissolved gas and the free gas bubble. Assuming that the total void fraction should be kept below 105% of the background level, a preliminary design allowance level of gas entrainment is proposed as the map in terms of the entrainment ratio and the entrained bubble radius. Furthermore, the possibility of bubble removal is investigated to satisfy the allowance level.
O(
) reaction at forward angles and structure of the spin-dipole resonancesKawabata, Takahiro*; Ishikawa, Takatsugu*; Ito, M.*; Nakamura, M.*; Sakaguchi, Harutaka*; Takeda, H.*; Taki, T.*; Uchida, Makoto*; Yasuda, Yusuke*; Yosoi, Masaru*; et al.
Physical Review C, 65(6), p.064316_1 - 064316_12, 2002/06
Times Cited Count：20 Percentile：70.04(Physics, Nuclear)no abstracts in English
Uchiyama, Gunzo; Watanabe, Kazuo; Miyauchi, Masakatsu; Togashi, Yoshihiro; Nakahara, Yoshinori; Fukaya, Hiroyuki; Inagawa, Jun; Suzuki, Daisuke; Sonoda, Takashi; Kono, Nobuaki; et al.
Journal of Radiation Research, 42(Suppl.), p.S11 - S16, 2001/10
no abstracts in English
O (p,p') experimentKawabata, Takahiro*; Akimune, Hidetoshi*; Fujimura, Hisako*; Fujita, Hirohiko*; Fujita, Yoshitaka*; Fujiwara, Mamoru; Hara, Keigo*; Hatanaka, Kichiji*; Hosono, K.*; Ishikawa, Takatsugu*; et al.
Nuclear Instruments and Methods in Physics Research A, 459(1-2), p.171 - 176, 2001/02
Times Cited Count：17 Percentile：74.75(Instruments & Instrumentation)no abstracts in English
