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Hashimoto, Shoji*; Tanaka, Taku*; Komatsu, Masabumi*; Gonze, M.-A.*; Sakashita, Wataru*; Kurikami, Hiroshi; Nishina, Kazuya*; Ota, Masakazu; Ohashi, Shinta*; Calmon, P.*; et al.
Journal of Environmental Radioactivity, 238-239, p.106721_1 - 106721_10, 2021/11
Times Cited Count：11 Percentile：61.41(Environmental Sciences)This study was aimed at analysing performance of models for radiocesium migration mainly in evergreen coniferous forest in Fukushima, by inter-comparison between models of several research teams. The exercise included two scenarios of countermeasures against the contamination, namely removal of soil surface litter and forest renewal, and a specific konara oak forest scenario in addition to the evergreen forest scenario. All the models reproduced trend of time evolution of radiocesium inventories and concentrations in each of the components in forest such as leaf and organic soil layer. However, the variations between models enlarged in long-term predictions over 50 years after the fallout, meaning continuous field monitoring and model verification/validation is necessary.
-ray spectrometryYamada, Takashi*; Asai, Masato; Yonezawa, Chushiro*; Kakita, Kazutoshi*; Hirai, Shoji*
Radioisotopes, 69(9), p.287 - 297, 2020/09
We have confirmed that the commercially available Japanese "standard" gamma-ray analysis programs do not consider the effect of sample volume in calculating true coincidence summing (TCS) corrections, which results in underestimation of 
Cs radioactivity in cylindrical volume samples. In this work, we have developed and examined a practical TCS correction method for general Ge detectors which consider the effect of sample volume properly, and have confirmed that this method can reduce the Cs radioactivity underestimation to less than 1%.
Sr)(Co
Fe
)O
through 
neutron diffractions at 300 and 720 KIto, Takanori*; Hirai, Takene*; Yamashita, Junichi*; Watanabe, Shoji*; Kawata, Etsuya*; Kitamura, Naoto*; Idemoto, Yasushi*; Igawa, Naoki
Physica B; Condensed Matter, 405(8), p.2091 - 2096, 2010/04
Times Cited Count：15 Percentile：54.84(Physics, Condensed Matter)We analyze the mechanism of oxygen ion diffusion in (BaSr)(CoFe)O by using the Rietveld refinement, the maximum entropy method (MEM) analysis, and MEM-based pattern fitting (MPF) with neutron diffractions at 300 and 720 K. We speculate that when 
and neutron scattering density of O1(4
) site with a large number of vacancies metamorphose into that with anisotropy directed toward the O1(4) and O2(8
) sites at 720 K, the oxygen ions diffuse along the paths between O1(4) and O1(4), and O1(4) and O2(8).
-ray detectionInoshita, Shinya*; Suzuki, Shogo*; Okada, Yukiko*; Kato, Masahiko*; Hirai, Shoji*; Kimura, Atsushi; Hatsukawa, Yuichi; Toh, Yosuke; Koizumi, Mitsuo; Oshima, Masumi
Tetsu To Hagane, 94(9), p.345 - 350, 2008/09
"Tatara" is Japanese original steel making method. Steel made by "Tatara" is famous as low alloy and suited to "Kaji" process. By authors' study, it turned out that we could estimate the source region of raw material of Tatara by As and Sb concentration ratio in Tatara sample. But the concentration of these element in Tatara sample is very low (ppm or sub-ppm order), therefore, quantitative analysis is very difficult. In this study, we adopted Neutron Activation Analysis combined with Multiple -ray detection (NAAMG) to analyze As and Sb in "Tatara" sample (iron lump and sand iron, slag). NAAMG is high sensitive and non-destructive analysis method which combined NAA (Neutron Activation Analysis) and multiple -ray detectors. Each "Tatara" sample (iron lump, sand iron, slag) were irradiated for 1-2 h (for As measurement), 8-17 h (for Sb measurement) in JRR-3M HR irradiation field (thermal neutron flux was about 9.0
10
n/m 
s
). And cooling time was 4-5 days (As), and 19-36 days (Sb). Coincidence -rays were measured by -ray detector array, GEMINI-II. Counting time was 1-8 hours (As), and 2-41 hours (Sb). Quantification was made by comparison method. As a result of measurement, the concentration of As and Sb in all "Tatara" samples were determined by NAAMG and these were sub-ppm order. Lower Limit of Determination (LLD) of As was 0.1 ppm order and Sb is 0.01ppm order. From the above-mentioned point, the effectiveness of NAAMG to analyze trace element in "Tatara" sample was confirmed.
HfNCl superconductors with 
=22 KShamoto, Shinichi; Hirai, Atsuo*; Yamanaka, Shoji*; Aso, Naofumi*; Kajitani, Tsuyoshi*
Journal of Neutron Research, 12(4), p.295 - 300, 2004/12
Inelastic neutron scattering measurements have been performed on superconducting NaHfNCl powder samples with x=0.27 and 0.38 (T =22 K). We have observed several temperature dependent phonon anomalies, e.g., at E=15, 29, 76, and 81 meV for the former sample. A phonon peak with E=14.5 meV at Q=6 
increases for both samples with decreasing temperature below T=40 K, which is much higher than T. The phonon peak is assigned to an ab-plane vibrational mode, E
, of chlorine and hafnium atoms, which strongly modifies the electronic band structure. The phonon anomaly is discussed in terms of carrier inhomogeneity.
Shirai, Nobutoshi; Taguchi, Katsuya; Iitsuka, Shoji; ; ; Sudo, Toshiyuki
JNC TN8410 99-055, 69 Pages, 1999/09
As a part of the safety confirmation work of Tokai Reprocessing Plant, an assessment of the basic data for criticality safety and shielding design has already been reported. In that report, two plutonium solution storage cells were evaluated to be safe enough from a viewpoint of multiple unit criticality safety. In this report, additionai evaluation of multiple unit criticality safety was made for the main plant and the UO
storage which were designed in 1960's and constructed in 1970's. The evaluated cells and rooms are enriched uranium dissolution cell, adjustment and feeding cell, two second extraction cycle cells, third uranium cycle cell, uranium concentration and denitration rooms, third plutonium cycle cell, plutonium concentration cell, two plutonium solution storage cells, rework cell, and UO storage room. As a result, it was confirmed that these cells and rooms were safe enough from a viewpoint of multiple unit criticality safety.
Futakawa, Masatoshi; Iyoku, Tatsuo; Shirai, Hiroshi*; Takada, Shoji; Ishihara, Masahiro
Nucl. Eng. Des., 148, p.83 - 90, 1994/00
Times Cited Count：4 Percentile：42.28(Nuclear Science & Technology)no abstracts in English
JRR-2 Control Office; Kambara, Toyozo; Shoda, Katsuhiko; Hirata, Yutaka; Shoji, Tsutomu; Kohayakawa, Toru; Morozumi, Minoru; Kambayashi, Yuichiro; Shitomi, Hajimu; Kokanezawa, Takashi; et al.
JAERI 1027, 57 Pages, 1962/09
no abstracts in English
JRR-2 Critical Experiments Group; Kambara, Toyozo; Shoda, Katsuhiko; Hirata, Yutaka; Shoji, Tsutomu; Kohayakawa, Toru; Morozumi, Minoru; Kambayashi, Yuichiro; Shitomi, Hajimu; Kokanezawa, Takashi; et al.
JAERI 1025, 62 Pages, 1962/03
no abstracts in English
-ray emitters including Cs, 2; Study of the coincidence summing effect taking into account for the thickness of the cylindrical shaped volume sampleYamada, Takashi*; Abe, Takaaki*; Asai, Masato; Yonezawa, Chushiro*; Kakita, Kazutoshi*; Hirai, Shoji*
no journal, ,
The true coincidence summing corrections for cascade rays are usually carried out by using -ray detection efficiencies averaged over whole sample volume. This is not an exact method, but is recognized to be practically useful. However, a recent international comparison experiment suggested that this method provides slightly small correction factors. To solve this problem, we developed a method to calculate the true coincidence summing corrections for cylindrical shaped volume samples by dividing the volume sample into a number of plane samples, calculating the efficiencies for each plane sample with summing corrections, and integrating them over whole sample volume. This method improved the problem of small correction factors.
-ray emitters including Cs, 1; Collaborative experiment by the committee on preparation of reference materials for radioactivity analysis of JSACYonezawa, Chushiro*; Kakita, Kazutoshi*; Takahashi, Takanori*; Aono, Tatsuo*; Maeda, Satoshi; Abe, Takaaki*; Arakawa, Fumihiro*; Kiho, Nobuharu*; Akiyama, Masakazu*; Muramatsu, Isamu*; et al.
no journal, ,
no abstracts in English
Am(n,)
Am reaction and -ray emission probabilities of AmNakamura, Shoji; Ota, Masayuki; Harada, Hideo; Shirai, Osamu*; Yamana, Hajimu*
no journal, ,
no abstracts in English
-ray emission probabilities of Pa-233 and Np-238Harada, Hideo; Nakamura, Shoji; Ota, Masayuki; Shirai, Osamu*; Yamana, Hajimu*
no journal, ,
In order to determine the neutron capture cross section of Np-237 by thermal neutrons, the relevant -ray emission probabilities of Pa-233 and Np-238 were measured. The cross section was also independently measured by alpha-ray spectroscopic method.
-ray detectionInoshita, Shinya*; Hirai, Shoji*; Okada, Yukiko*; Suzuki, Shogo*; Kimura, Atsushi; Oshima, Masumi
no journal, ,
no abstracts in English
Hashimoto, Shoji*; Tanaka, Taku*; Komatsu, Masabumi*; Gonze, M.-A.*; Sakashita, Wataru*; Kurikami, Hiroshi; Nishina, Kazuya*; Ota, Masakazu; Ohashi, Shinta*; Calmon, P.*; et al.
no journal, ,
We applied modelling approaches to evaluate the past and future dynamics of 
Cs in forests. In the model inter-comparison exercise using Fukushima data, six models with diverse model structures, processes, parameters and numerical approaches joined this exercise and the performance and uncertainties of the state-of-the-art models were explored. The inter-comparison revealed that, after appropriate calibration, the models reproduced the observed data reliably and the ranges of calculated trajectories were narrow in the early phase after the fallout. However, the envelope of the calculated model end points enlarged in long-term simulations over 50 years after the fallout. The model-inter comparison exercise emphasizes the importance of decadal data for various forest types and repetitive verification/validation processes using holistic, long-term data to improve the models and to update the forecasting capacity of the models.
