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Nakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Rovira Leveroni, G.; Kimura, Atsushi
Journal of Nuclear Science and Technology, 62(3), p.300 - 307, 2025/03
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Nakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Rovira Leveroni, G.; Kimura, Atsushi
Journal of Nuclear Science and Technology, 14 Pages, 2025/00
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Tsutsui, Satoshi; Ito, Takashi; Nakamura, Jin*; Yoshida, Mio*; Kobayashi, Yoshio*; Yoda, Yoshitaka*; Nakamura, Jumpei*; Koda, Akihiro*; Higashinaka, Ryuji*; Aoki, Dai*; et al.
Interactions (Internet), 245(1), p.55_1 - 55_9, 2024/12
Tsutsui, Satoshi; Higashinaka, Ryuji*; Mizumaki, Masaichiro*; Kobayashi, Yoshio*; Nakamura, Jin*; Ito, Takashi; Yoda, Yoshitaka*; Matsuda, Tatsuma*; Aoki, Yuji*; Sato, Hideyuki*
Interactions (Internet), 245(1), p.9_1 - 9_10, 2024/12
Nakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Rovira Leveroni, G.; Kimura, Atsushi
Journal of Nuclear Science and Technology, 61(11), p.1415 - 1430, 2024/11
Times Cited Count:1 Percentile:62.55(Nuclear Science & Technology)Neutron capture cross-sections of nuclides targeted for decommissioning are necessary to contribute to the evaluation of radioactivity produced. The present study, Sc,
Cu,
Zn,
Ag and
In nuclides were selected as target ones, and their thermal-neutron capture cross-sections were measured by an activation method at Kyoto University Research Reactor. The thermal-neutron capture cross-sections were obtained as follows: 27.18
0.28 barn for
Sc(n,
)
Sc, 4.34
0.06 barn for
Cu(n,
)
Cu, 0.719
0.011 barn for
Zn(n,
)
Zn, 4.05
0.05 barn for
Ag(n,
)
Ag and 8.53
0.27 barn for
In(n,
)
In
. The results for
Sc and
Zn nuclides supported evaluated values within the limits of uncertainties, while those for the other nuclides were slightly different from evaluated ones. The obtained results are useful not only for the evaluation of production amount, but also for the monitor selection other than Au and Co by considering those nuclides as flux monitors.
Nakamura, Shoji; Endo, Shunsuke; Rovira Leveroni, G.; Kimura, Atsushi; Shibahara, Yuji*
KURNS Progress Report 2023, P. 46, 2024/07
The present work is an attempt to measure the thermal-neutron capture cross-sections for some nuclides which are of importance in decommissioning to evaluate produced radioactivity. This work selected some of objective nuclides for decommissioning, such as Fe,
Er and
Hf, and measured thermal-neutron capture cross-sections for these nuclides by a neutron activation method at Kyoto University Research Reactor. The present results were obtained as follows:1.23
0.03 barn for
Fe(n,
)
Fe reaction, 8.19
0.35 barn for
Er(n,
)
Er reaction and 13.57
0.14 barn for
Hf(n,
)
Hf reaction. As a by-product, the measurement of Hf sample also presented 0.427
0.006 barn for
Hf(n,
)
mHf reaction. It has been revealed that the data adopted in an evaluated data library differ from the present results by more than experimental uncertainties.
Koyama, Shinichi; Ikeuchi, Hirotomo; Mitsugi, Takeshi; Maeda, Koji; Sasaki, Shinji; Onishi, Takashi; Tsai, T.-H.; Takano, Masahide; Fukaya, Hiroyuki; Nakamura, Satoshi; et al.
Hairo, Osensui, Shorisui Taisaku Jigyo Jimukyoku Homu Peji (Internet), 216 Pages, 2023/11
In FY 2021 and 2022, JAEA perfomed the subsidy program for "the Project of Decommissioning and Contaminated Water Management (Development of Analysis and Estimation Technology for Characterization of Fuel Debris (Development of Technologies for Enhanced Analysis Accuracy, Thermal Bahavior Estimation, and Simplified Analysis of Fuel Debris)" started in FY 2021. This presentation material summarized the results of the project, which will be available shortly on the website of Management Office for the Project of Decommissioning, Contaminated Water and Treated Water Management.
Nakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Kimura, Atsushi
Journal of Nuclear Science and Technology, 60(11), p.1361 - 1371, 2023/11
Times Cited Count:3 Percentile:65.16(Nuclear Science & Technology)The thermal-neutron capture cross section () and resonance integral (I
) for
Nb among nuclides for decommissioning were measured by an activation method and the half-life of
Nb by mass analysis. Niobium-93 samples were irradiated with a hydraulic conveyer installed in the research reactor in Institute for Integral Radiation and Nuclear Science, Kyoto University. Gold-aluminum, cobalt-aluminum alloy wires were used to monitor thermal-neutron fluxes and epi-thermal Westcott's indexes at an irradiation position. A 25-
m-thick gadolinium foil was used to sort out reactions ascribe to thermal-and epi-thermal neutrons. Its thickness provided a cut-off energy of 0.133 eV. In order to attenuate radioactivity of
Ta due to impurities, the Nb samples were cooled for nearly 2 years. The induced radio activity in the monitors and Nb samples were measured by
-ray spectroscopy. In analysis based on Westcott's convention, the
and I
values were derived as 1.11
0.04 barn and 10.5
0.6 barn, respectively. After the
-ray measurements, mass analysis was applied to the Nb sample to obtain the reaction rate. By combining data obtained by both
-ray spectroscopy and mass analysis, the half-life of
Nb was derived as (2.00
0.15)
10
years.
Nakamura, Shoji; Shibahara, Yuji*; Kimura, Atsushi; Endo, Shunsuke; Shizuma, Toshiyuki*
Journal of Nuclear Science and Technology, 60(9), p.1133 - 1142, 2023/09
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)In recent years, research has been advanced on lead-cooled fast reactors and accelerator drive systems, and it is required to improve the accuracy of the neutron capture cross section of Pb isotopes. Although Pb has a small natural abundance, it is of importance because it produces the long-lived radionuclide
Pb (17.3 million years) by neutron capture reaction. However, it is difficult to measure its cross section by a conventional activation method using a nuclear reactor because the induced radioactivity of
Pb is weak. Hence, the cross-section measurement was performed by applying mass spectrometry. This presentation gives the details of the experiment and the results obtained in the neutron capture cross-section measurement of
Pb using mass spectroscopy.
Nakamura, Shoji; Endo, Shunsuke; Kimura, Atsushi; Shibahara, Yuji*
KURNS Progress Report 2022, P. 73, 2023/07
The present study is concerned with the neutron capture cross-sections that contribute to the evaluation of the amount of radionuclides possessing problems in decommissioning. In this study, Sc,
Cu,
Zn,
Ag,
In and
W were selected among the objective nuclides, and their thermal-neutron capture cross-sections were measured using TC-Pn equipment of the KUR of the Institute for Integrated Radiation and Nuclear Science, Kyoto University. High purity metal samples were prepared. A gold-aluminum ally wire, cobalt and molybdenum foils were used to monitor the neutron flux at the irradiation position of TC-Pn. The flux monitors and metal samples were irradiated for 1 hour at 1-MW operation of the KUR. After irradiation, the irradiation capsule was opened, samples and flux monitors were enclosed in a vinyl bag one by one, and then
rays emitted from the samples and monitors were measured with a high-purity Ge detector. The thermal-neutron flux component was derived with the reaction rates of flux monitors (
Au,
Co and
Mo) on the basis of Westcott's convention, and found to be (5.92
0.10)
10
n/cm
/sec at the irradiation position. The measured reaction rate for each metal sample divided by the evaluated thermal-neutron capture cross-section should give the same value of the thermal-neutron flux component if the cross section is suitable. This time, we found that the cross sections of
Sc and
Zn were consistent with the evaluated one, but those of other nuclides were inconsistent with their evaluated ones; that is, it turned out that their thermal-neutron capture cross-sections should be modified.
Nishino, Saki; Okada, Jumpei; Watanabe, Kazuki; Furuuchi, Yuta; Yokota, Satoru; Yada, Yuji; Kusaka, Shota; Morokado, Shiori; Nakamura, Yoshinobu
JAEA-Technology 2023-011, 39 Pages, 2023/06
Tokai Reprocessing Plant (TRP) which shifted to decommissioning phase in 2014 had nuclear fuel materials such as the spent fuel sheared powder, the diluted plutonium solution and the uranium solution in a part of the reprocessing main equipment because TRP intended to resume reprocessing operations when it suspended the operations in 2007. Therefore, we have planned to remove these nuclear materials in sequence as Flush-out before beginning the decommissioning, and conducted removal of the spent fuel sheared powder as the first stage. The spent fuel sheared powder that had accumulated in the cell of the Main Plant (MP) as a result of the spent fuel shearing process was recovered from the cell floor, the shearing machine and the distributor between April 2016 and April 2017 as part of maintenance. Removing the recovered spent fuel sheared powder was conducted between June 2022 and September 2022. In this work, the recovered powder was dissolved in nitric acid at the dissolver in a small amount in order to remove it safely and early, and the dissolved solution was sent to the highly radioactive waste storage tanks without separating uranium and plutonium. Then, the dissolved solution transfer route was rinsed with nitric acid and water. Although about 15 years had passed since previous process operations, the removing work was successfully completed without any equipment failure because of the organization of a system that combines veterans experienced the operation with young workers, careful equipment inspections, and worker education and training. Removing this powder was conducted after revising the decommissioning project and obtaining approval from the Nuclear Regulation Authority owing to operating a part of process equipment.
Kimura, Atsushi; Nakamura, Shoji; Endo, Shunsuke; Rovira Leveroni, G.; Iwamoto, Osamu; Iwamoto, Nobuyuki; Harada, Hideo; Katabuchi, Tatsuya*; Terada, Kazushi*; Hori, Junichi*; et al.
Journal of Nuclear Science and Technology, 60(6), p.678 - 696, 2023/06
Times Cited Count:2 Percentile:30.61(Nuclear Science & Technology)Rovira Leveroni, G.; Kimura, Atsushi; Nakamura, Shoji; Endo, Shunsuke; Iwamoto, Osamu; Iwamoto, Nobuyuki; Katabuchi, Tatsuya*; Kodama, Yu*; Nakano, Hideto*; Hori, Junichi*; et al.
EPJ Web of Conferences, 284, p.06007_1 - 06007_4, 2023/05
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Kodama, Yu*; Katabuchi, Tatsuya*; Rovira Leveroni, G.; Kimura, Atsushi; Nakamura, Shoji; Endo, Shunsuke; Nakano, Hideto*; Sato, Yaoki*; Hori, Junichi*; Shibahara, Yuji*; et al.
EPJ Web of Conferences, 284, p.01024_1 - 01024_3, 2023/05
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Katabuchi, Tatsuya*; Iwamoto, Osamu; Hori, Junichi*; Kimura, Atsushi; Iwamoto, Nobuyuki; Nakamura, Shoji; Rovira Leveroni, G.; Endo, Shunsuke; Shibahara, Yuji*; Terada, Kazushi*; et al.
EPJ Web of Conferences, 281, p.00014_1 - 00014_4, 2023/03
Nakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Kimura, Atsushi
Journal of Nuclear Science and Technology, 59(11), p.1388 - 1398, 2022/11
Times Cited Count:1 Percentile:15.53(Nuclear Science & Technology)The present study selected Np among radioactive nuclides and aimed to measure the thermal-neutron capture cross-section for
Np in a well-thermalized neutron field by an activation method. A
Np standard solution was used for irradiation samples. A thermal-neutron flux at an irradiation position was measured with neutron flux monitors:
Sc,
Co,
Mo,
Ta and
Au. The
Np sample and flux monitors were irradiated together for 30 minutes in the graphite thermal column equipped with the Kyoto University Research Reactor. The similar irradiation was carried out twice. After the irradiations, the
Np samples were quantified using 312-keV gamma ray emitted from
Pa in a radiation equilibrium with
Np. The reaction rates of
Np were obtained from gamma-ray peak net counts given by
Np, and then the thermal-neutron capture cross-section of
Np was found to be 173.8
4.4 barn by averaging the results obtained by the two irradiations. The present result was in agreement with the reported data given by a time-of-flight method within the limit of uncertainty.
Nakamura, Shoji; Endo, Shunsuke; Kimura, Atsushi; Shibahara, Yuji*
KURNS Progress Report 2021, P. 93, 2022/07
In terms of nuclear transmutation studies of minor actinides in nuclear wastes, the present work selected Np among them and aimed to measure the thermal-neutron capture cross-section of
Np using a well-thermalized neutron field by a neutron activation method because there have been discrepancies among reported cross-section data. A
Np standard solution was used for irradiation samples. The thermal-neutron flux at an irradiation position was measured with flux monitors:
Sc,
Co,
Mo,
Ta and
Au. The
Np sample was irradiated together with the flux monitors for 30 minutes in the graphite thermal column equipped in the Kyoto University Research Reactor. The similar irradiation was repeated once more to confirm the reproducibility of the results. After irradiation, the
Np samples were quantified using 312-keV gamma-ray emitted from
Pa in radiation equilibrium with
Np. The reaction rates of
Np were obtained from the peak net counts of gamma-rays emitted from generated
Np, and then the thermal-neutron capture cross-section of
Np was found to be 173.8
4.7 barn by averaging the results obtained by the two irradiations. The present result was in agreement with the reported data given by a time-of-flight method within a limit of uncertainty.
Rovira Leveroni, G.; Kimura, Atsushi; Nakamura, Shoji; Endo, Shunsuke; Iwamoto, Osamu; Iwamoto, Nobuyuki; Katabuchi, Tatsuya*; Kodama, Yu*; Nakano, Hideto*; Sato, Yaoki*; et al.
Journal of Nuclear Science and Technology, 59(5), p.647 - 655, 2022/05
Times Cited Count:1 Percentile:10.40(Nuclear Science & Technology)Rovira Leveroni, G.; Iwamoto, Osamu; Kimura, Atsushi; Nakamura, Shoji; Iwamoto, Nobuyuki; Endo, Shunsuke; Katabuchi, Tatsuya*; Terada, Kazushi*; Kodama, Yu*; Nakano, Hideto*; et al.
JAEA-Conf 2021-001, p.156 - 161, 2022/03
Tsutsui, Satoshi; Higashinaka, Ryuji*; Nakamura, Raito*; Fujiwara, Kosuke*; Nakamura, Jin*; Kobayashi, Yoshio*; Ito, Takashi; Yoda, Yoshitaka*; Kato, Kazuo*; Nitta, Kiyofumi*; et al.
Hyperfine Interactions, 242(1), p.32_1 - 32_10, 2021/12
Times Cited Count:1 Percentile:75.41(Physics, Atomic, Molecular & Chemical)