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Yamauchi, Michinori*; Ochiai, Kentaro; Morimoto, Yuichi*; Wada, Masayuki*; Sato, Satoshi; Nishitani, Takeo
Radiation Protection Dosimetry, 116(1-4), p.542 - 546, 2005/12
Times Cited Count:3 Percentile:24.27(Environmental Sciences)no abstracts in English
Morimoto, Yuichi*; Ochiai, Kentaro; Nishio, Takashi*; Wada, Masayuki*; Yamauchi, Michinori*; Nishitani, Takeo
Journal of Nuclear Science and Technology, 41(Suppl.4), p.42 - 45, 2004/03
no abstracts in English
Morimoto, Yuichi*; Ochiai, Kentaro; Sato, Satoshi; Hori, Junichi; Yamauchi, Michinori*; Nishitani, Takeo
Fusion Engineering and Design, 69(1-4), p.643 - 648, 2003/09
Times Cited Count:4 Percentile:31.71(Nuclear Science & Technology)no abstracts in English
Sato, Satoshi; Ochiai, Kentaro; Hori, Junichi; Verzilov, Y. M.; Klix, A.; Wada, Masayuki*; Terada, Yasuaki*; Yamauchi, Michinori*; Morimoto, Yuichi*; Nishitani, Takeo
Nuclear Fusion, 43(7), p.527 - 530, 2003/07
Times Cited Count:15 Percentile:44.21(Physics, Fluids & Plasmas)no abstracts in English
Yamauchi, Michinori*; Nishitani, Takeo; Ochiai, Kentaro; Morimoto, Yuichi*; Hori, Junichi; Ebisawa, Katsuyuki*; Kasai, Satoshi; Walker, C.*
Review of Scientific Instruments, 74(3), p.1730 - 1734, 2003/03
Times Cited Count:22 Percentile:71.01(Instruments & Instrumentation)no abstracts in English
Hori, Junichi; Maekawa, Fujio; Wada, Masayuki*; Ochiai, Kentaro; Yamauchi, Michinori*; Morimoto, Yuichi*; Terada, Yasuaki; Klix, A.; Nishitani, Takeo
Fusion Engineering and Design, 63-64, p.271 - 276, 2002/12
Times Cited Count:2 Percentile:17.07(Nuclear Science & Technology)In order to the waste management method and the safety design of future D-T fusion reactor, it is important to consider the radioactivity productions via not only primary neutron reactions but also sequential charged particle reactions (SCPR). Especially, on the surface of a coolant channel many recoiled protons are generated by the neutron irradiation with coolant water, so it is apprehensive that the undesirable radioactive nuclide production yields via SCPR are enhanced. In this work, the laminated sample pieces of fusion material foils (V, Fe, W, Ti, Pb, Cu) were made and attached on a polyethylene board to simulate water flowing inside a coolant channel. They were irradiated with D-T neutrons. The effective radioactivity cross section and the depth distribution of the radioactivity production yields due to SCPR were obtained for each material. On the other hand, the estimated values were compared with the experimental ones.
Morimoto, Yuichi*; Ochiai, Kentaro; Maekawa, Fujio; Wada, Masayuki*; Nishitani, Takeo; Takeuchi, Hiroshi
Journal of Nuclear Materials, 307-311(Part2), p.1052 - 1056, 2002/12
Times Cited Count:0 Percentile:0.01(Materials Science, Multidisciplinary)Decay heat is one of the most important factors for the safety aspect of ITER. Especially, prediction of decay heat with uncertainty less than 15% for the three most important materials, i.e., copper, type-316 stainless steel (SS-316) and tungsten, is strongly requested by designers of ITER. To provide experimental decay heat data needed for validation of decay heat calculations for SS316 and copper, an experiment was conducted as the ITER/EDA task T-426. An ITER-like neutron field was constructed, and decay heat source distributions in thick copper and SS316 plates were measured with Whole Energy Absorption Spectrometer. The measured decay heat distributions in the thick sample plates were compared with the predicted values by MCNP calculations. It was found that the use of an effective activation cross section calculated by MCNP was needed to consider the self-shielding effects and, for both cases, MCNP calculations could predict decay heat adequately.
Ochiai, Kentaro; Klix, A.; Hori, Junichi; Morimoto, Yuichi*; Wada, Masayuki*; Nishitani, Takeo
Journal of Nuclear Science and Technology, 39(Suppl.2), p.1147 - 1150, 2002/08
Thermal blanket type as one of conceptual designs for DEMO-fusion blanket is proposed. We have irradiated the trial blanket assembly which was stratified 95-% enriched Li2TiO3,F82H and beryllium block using Fusion Neutron Source (FNS) and verified the accuracy of these parameters by measurements of tritium and gamma-ray emitted from samples of95-% enriched Li2TiO3 and F82H. We have used the liquid scintillated counter as the method of tritium measurement. Activation foils, NE213, Si-SBD and Fission chamber have usedto measure neutron fluence. Moreover, we have concurrently measured the gamma rays of 56Mn, 54Mn, 187W and 51Cr was produced by 56Fe(n,p), 54Fe(n,p), 186W(n,g), 52Cr(n,2n) and 50Cr(n,g) in F82H. We have used the JENDL Fusion File library and MCNP to verify the accuracy tritium-production rate and 56Mn, 54Mn, 187W and 51Cr. From the results of above experiments, MCNP that uses the JENDL-FF nuclear data library can predict the nuclear parameters such as TPR, Nb, 56Mn, In and 54Mn in the test assemblies within an accuracy of 10%.
Klix, A.; Ochiai, Kentaro; Terada, Yasuaki; Morimoto, Yuichi*; Yamauchi, Michinori*; Hori, Junichi; Nishitani, Takeo
Fusion Science and Technology, 41(3, Part2), p.1040 - 1043, 2002/05
Li-enriched LiTiO is one of the candidate materials for the breeding blanket of the fusion DEMO reactor. Therefore, it is necessary to measure the tritium production performance and estimate the accuracy of the measurement method. The JAERI Fusion Neutronics Source (FNS) group has carried out experiments with breeding blanket mock-ups composed of layers of beryllium, ferritic steel F82H and enriched LiTiO. Pellets of enriched LiTiO with a diameter of 12mm and a thickness of 2mm were used as detectors inside the tritium breeding layer. After irradiation, the pellets were dissolved and the tritium activity in the sample solution was measured by liquid scintillation counting. The experimentally obtained tritium production profile in the lithium titanate layer agreed well with MCNP calculations within the estimated error of the measured values (10%). The calculation-experiment ratio was close to one for all samples. Tritium loss from the pellet during storage time (a few days) was experimentally found to be negligible.
Yamauchi, Michinori*; Nishitani, Takeo; Ochiai, Kentaro; Morimoto, Yuichi*; Hori, Junichi; Ebisawa, Katsuyuki*; Kasai, Satoshi
JAERI-Tech 2002-032, 41 Pages, 2002/03
A micro-fission chamber and a dummy chamber without uranium were fabricated and the performance was tested. They are designed to be installed inside the vacuum vessel of compact ITER (ITER-FEAT) for neutron monitoring. Vacuum leak rate of the chamber, resistances between central conductor and outer sheath, and mechanical strength up to 50G acceleration were confirmed to meet design criteria. Gamma-ray sensitivity was measured with Co gamma-ray irradiation facility at JAERI Takasaki. The output signals for gamma-rays in Campbelling mode were estimated to be less than 0.1% those by neutrons at the location behind the blanket module in ITER-FEAT. Detector response for 14 MeV neutrons was investigated with the FNS facility. Excellent linearity between count rates and neutron fluxes was confirmed. According to the test for the change of surrounding materials, the sensitivity was enhanced by slow-downed neutrons, which agreed with the calculation result by MCNP-4C code. As a result, it was concluded that the developed micro-fission chamber is applicable for ITER-FEAT.
Maekawa, Fujio; Ochiai, Kentaro; Shibata, Keiichiro*; Kasugai, Yoshimi; Wada, Masayuki*; Morimoto, Yuichi*; Takeuchi, Hiroshi
Fusion Engineering and Design, 58-59, p.595 - 600, 2001/11
Times Cited Count:11 Percentile:62.08(Nuclear Science & Technology)no abstracts in English
Nakamura, Hiroo; Morimoto, Yuichi*; Ochiai, Kentaro; Sugimoto, Masayoshi; Nishitani, Takeo; Takeuchi, Hiroshi
JAERI-Review 2000-016, 47 Pages, 2000/10
no abstracts in English
*; Okumura, Keisuke
JAERI-M 92-068, 107 Pages, 1992/05
no abstracts in English
*; Okumura, Keisuke;
JAERI-M 92-067, 35 Pages, 1992/05
no abstracts in English