KeV-neutron capture cross-section measurement of Au with a Cr-filtered neutron beam at the ANNRI beamline of MLF/J-PARC

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

https://doi.org/10.1080/00223131.2021.1997666

Am neutron capture cross section in the keV region using Si and Fe-filtered neutron beams

Rovira Leveroni, G.; Kimura, Atsushi; Nakamura, Shoji; Endo, Shunsuke; Iwamoto, Osamu; Iwamoto, Nobuyuki; Katabuchi, Tatsuya*; Kodama, Yu*; Nakano, Hideto*

Journal of Nuclear Science and Technology, 11 Pages, 2022/00

https://doi.org/10.1080/00223131.2022.2116496

Two-dimensional scintillation neutron detectors for the extension of SENJU diffractometer

Nakamura, Tatsuya; To, Kentaro; Koizumi, Tomokatsu; Kiyanagi, Ryoji; Ohara, Takashi; Ebine, Masumi; Sakasai, Kaoru

Proceedings of 2020 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2020), Vol.1, p.483 - 484, 2021/09

https://doi.org/10.1109/NSS/MIC42677.2020.9507813

Two-dimensional neutron detectors were developed for the extension of SENJU time-of-flight Laue single crystal neutron diffractometer in J-PARC MLF. The detectors are to be installed at the additional detector bank for the SENJU instrument. The detector module is made based on ZnS scintillator and wavelength-shifting fiber technology, where each detector module maintains a neutron-sensitive area of 256256 mm with a pixel size of 44 mm. To meet the tight space limitation in the instrument, the detector was designed as compact as possible. The detector has a depth of 170 mm, which is about 40% smaller than that of the original SENJU detector. All four produced detectors exhibited similar detector performances: detection efficiency 50-60% for 2- neutron, Co gamma-ray sensitivity 110, count uniformity 3-6%.

Research and examination of seismic safety evaluation and function maintenance for important equipment in nuclear facilities

Furuya, Osamu*; Fujita, Satoshi*; Muta, Hitoshi*; Otori, Yasuki*; Itoi, Tatsuya*; Okamura, Shigeki*; Minagawa, Keisuke*; Nakamura, Izumi*; Fujimoto, Shigeru*; Otani, Akihito*; et al.

Proceedings of ASME 2021 Pressure Vessels and Piping Conference (PVP 2021) (Internet), 6 Pages, 2021/07

Since the Fukushima accident, with the higher safety requirements of nuclear facilities in Japan, suppliers, manufacturers and academic societies have been actively considering the reconstruction of the safety of nuclear facilities from various perspectives. The Nuclear Regulation Authority has formulated new regulatory standards and is in operation. The new regulatory standards are based on defense in depth, and have significantly raised the levels of natural hazards and have requested to strengthen the countermeasures from the perspective of preventing the simultaneous loss of safety functions due to common factors. Facilities for dealing with specific serious accidents are required to have robustness to ensure functions against earthquakes that exceed the design standards to a certain extent. In addition, since the probabilistic risk assessment (PRA) and the safety margin evaluation are performed to include the range beyond the design assumption in the safety improvement evaluation, it is very important to extent the special knowledge in the strength of important equipment for seismic safety. This paper summarizes the research and examination results of specialized knowledge on the concept of maintaining the functions of important seismic facilities and the damage index to be considered by severe earthquakes. In the other paper, the study on reliability of seismic capacity analysis for important equipment in nuclear facilities will be reported.

Mode distribution analysis for superionic melt of CuI by coherent quasielastic neutron scattering

Kawakita, Yukinobu; Kikuchi, Tatsuya*; Tahara, Shuta*; Nakamura, Mitsutaka; Inamura, Yasuhiro; Maruyama, Kenji*; Yamauchi, Yasuhiro*; Kawamura, Seiko; Nakajima, Kenji

JPS Conference Proceedings (Internet), 33, p.011071_1 - 011071_6, 2021/03

BB2019-1144.pdf:0.7MB

https://doi.org/10.7566/JPSCP.33.011071

CuI is a well-known superionic conductor in a high temperature solid phase where the mobile cations migrate between interstitial sites in the f.c.c. sublattice formed by iodine ions. Even in the molten state, it shows several features suggesting collective or cooperative ionic motion. MD results show that Cu diffuses much faster than I. The Cu-Cu partial structure factor have a FSDP which indicates a medium-range ordering of Cu ions. Moreover the Cu-Cu partial pair distribution deeply penetrates into the nearest neighboring Cu-I shell. To reveal origin such anomalous behaviors of molten CuI, we performed quaiselastic neutron scattering (QENS) by the disk-chopper spectrometer AMATERAS at MLF, J-PARC. To interpret the total dynamic structure factor obtained from coherent QENS, the mode distribution analysis was applied. It is found that the motion of iodine is a kind of fluctuating within an almost local area while Cu ions diffuse much faster than iodine ions.

Discovery of a new low energy neutron resonance of Y

Katabuchi, Tatsuya*; Toh, Yosuke; Mizumoto, Motoharu*; Saito, Tatsuhiro*; Terada, Kazushi*; Kimura, Atsushi; Nakamura, Shoji; Huang, M.*; Rovira Leveroni, G.; Igashira, Masayuki*

European Physical Journal A, 57(1), p.4_1 - 4_4, 2021/01

https://doi.org/10.1140/epja/s10050-020-00320-8

Evaluation of gamma-ray strength function based on measured gamma-ray pulse-height spectra in time-of-flight neutron capture experiments

Iwamoto, Nobuyuki; Nakamura, Shoji; Kimura, Atsushi; Katabuchi, Tatsuya*; Rovira, G.*; Hara, Kaoru*; Iwamoto, Osamu

EPJ Web of Conferences, 239, p.17016_1 - 17016_4, 2020/09

https://doi.org/10.1051/epjconf/202023917016

A Large area position-sensitive scintillation neutron detector for upgrading SENJU diffractometer

Nakamura, Tatsuya; To, Kentaro; Ebine, Masumi; Birumachi, Atsushi; Sakasai, Kaoru

Proceedings of 2019 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2019), Vol.1, p.735 - 736, 2020/08

https://doi.org/10.1109/NSS/MIC42101.2019.9059981

A large area, position-sensitive scintillation neutron detector was developed for upgrading the SENJU, time-of-flight Laue single crystal neutron diffractometer, in J-PARC MLF. The detector has a neutron-sensitive area of 512 512 mm with a pixel size of 4 4 mm. The detector was developed for upgrading of the SENJU instrument. The large area detector is to be installed below the vacuum tank to enlarge a covering solid angle. A Li:ZnS (Ag) scintillator and wavelength-shifting fiber technologies are employed. Each fiber channel is read out individually with photon counting mode. The electronics boards are implemented at the backside of the detector, enabling the detector depth as short as 20 cm. The detector exhibited a detection efficiency of 45% for thermal neutron. No degradation in fiber position and in neutron sensitivity has been observed over one year after production. In this paper, detector design and detector performances are presented.

High peak-current lightning discharges associated with downward terrestrial gamma-ray flashes

Wada, Yuki*; Enoto, Teruaki*; Nakamura, Yoshitaka*; Morimoto, Takeshi*; Sato, Mitsuteru*; Ushio, Tomoo*; Nakazawa, Kazuhiro*; Yuasa, Takayuki*; Yonetoku, Daisuke*; Sawano, Tatsuya*; et al.

Journal of Geophysical Research; Atmospheres, 125(4), p.e2019JD031730_1 - e2019JD031730_11, 2020/02

https://doi.org/10.1029/2019JD031730

Neutron capture reaction data measurement of minor actinides in fast neutron energy region for study on nuclear transmutation system

Katabuchi, Tatsuya*; Iwamoto, Osamu; Hori, Junichi*; Iwamoto, Nobuyuki; Kimura, Atsushi; Nakamura, Shoji; Shibahara, Yuji*; Terada, Kazushi*

JAEA-Conf 2019-001, p.193 - 197, 2019/11

https://doi.org/10.11484/jaea-conf-2019-001