Reviewing codes and standards for long term operation in Japan

Murakami, Kenta*; Arai, Taku*; Yamada, Koji*; Momma, Kensuke*; Tsuji, Takashi*; Nakagawa, Nobuyuki*; Onizawa, Kunio

Transactions of the 27th International Conference on Structural Mechanics in Reactor Technology (SMiRT 27) (Internet), 3 Pages, 2024/03

This paper studied the future vision of codes and standards in Japan by systematically comparing Japanese regulatory rules, standards, and industry guides related to long term operation with international safety standards, and confirmed that the Japanese standard system generally meets their recommendations. The recommendation for the future improvements of Japanese codes and standards were summarized into five items.

Thermally altered subsurface material of asteroid (162173) Ryugu

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.

Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03

https://doi.org/10.1038/s41550-020-01271-2

Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.

Study on engineering technologies in the Mizunami Underground Research Laboratory; FY2012 (Contract research)

Fukaya, Masaaki*; Noda, Masaru*; Hata, Koji*; Takeda, Yoshinori*; Akiyoshi, Kenji*; Ishizeki, Yoshikazu*; Kaneda, Tsutomu*; Sato, Shin*; Shibata, Chihoko*; Ueda, Tadashi*; et al.

JAEA-Technology 2014-019, 495 Pages, 2014/08

JAEA-Technology-2014-019.pdf:82.23MB

The researches on engineering technology in the Mizunami Underground Research Laboratory (MIU) plan consists of (1) research on engineering technology deep underground, and (2) research on engineering technology as a basis of geological disposal. The former research is mainly aimed in this study, which is categorized in (a) development of design and construction planning technologies, (b) development of construction technologies, (c) development of countermeasure technologies, and (d) development of technologies for security. In this study, the researches on engineering technology are being conducted in these four categories by using data measured during construction as a part of the second phase of the MIU plan.

Estimation method of uplift during late Quaternary in an inland area; Case study of fluvial terraces along the Kaburagawa river and Tokigawa river

Yasue, Kenichi; Tajikara, Masayoshi*; Tanikawa, Shinichi; Sugai, Toshihiko; Yamada, Koji*; Umeda, Koji

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 18(2), p.51 - 62, 2011/12

https://doi.org/10.3327/jnuce.18.51

We attempt to improve the reliability of the TT method, quantitative estimation of inland uplift rate based on the model in which river bed elevation is controlled by the climate change. In order to recognize fluvial terraces in the glacial epoch, it is important to note that flood deposit and phytolith as indicators of the determination of the emergence horizon and the estimate of the paleoclimate, respectively. The identification of thick sediments suggesting the decline of the tractive force in the glacial epoch are also useful for highly accurate comparison and chronology of the terrace. This paper shows that the synthetic examination based on many data obtained by these techniques enables a highly accurate comparison and chronology of the terrace to estimate uplift for the last 100,000 years with high reliability.

Current status of the 4SEASONS spectrometer at J-PARC

Kajimoto, Ryoichi; Yokoo, Tetsuya*; Nakajima, Kenji; Nakamura, Mitsutaka; Inamura, Yasuhiro; Soyama, Kazuhiko; Ino, Takashi*; Oyama, Kenji*; Sakai, Makiko; Aizawa, Kazuya; et al.

no journal, , 

4SEASONS is one of the day-one chopper spectrometers for the spallation neutron facility in Japan Proton Accelerator Research Complex (J-PARC). The spectrometer targets high- superconductors and related strongly correlated materials utilizing incident energies of 5-300 meV. 4SEASONS supplies high flux at a sample by moderating the resolution (-6% at ) and incorporating efficient neutron optic devices. A new Fermi chopper is designed to multiply the measurement efficiency by repetition rate multiplication (RRM). Recently, we have decided to enlarge the detector coverage by in horizontal direction (with the maximum scattering angle being ) to let the spectrometer have more flexibility. The designing of the vacuum scattering chamber has been almost completed. Examination of the 2.5m-He PSD on neutron beam and manufacturing of a prototype of a slit package of the new chopper are going on.

4SEASONS; A High-intensity chopper spectrometer for inelastic neutron scattering at J-PARC/MLF

Kajimoto, Ryoichi; Nakamura, Mitsutaka; Yokoo, Tetsuya*; Nakajima, Kenji; Inamura, Yasuhiro; Takahashi, Nobuaki; Maruyama, Ryuji; Soyama, Kazuhiko; Shibata, Kaoru; Suzuya, Kentaro; et al.

no journal, , 

4SEASONS is one of the neutron chopper spectrometers in J-PARC/MLF. It is intended to provide very high counting rate up to 300 meV neutron energy with medium resolution (% at ) to efficiently collect weak inelastic signals from novel spin and lattice dynamics especially in high- superconductors and related materials. To achieve this goal, the spectrometer equips advanced instrumental design such as an elliptic-shaped converging neutron guide coated with high- (-4) supermirror, long-length (2.5 m) He PSDs arranged cylindrically inside the vacuum scattering chamber. Furthermore, the spectrometer is ready for multi-incident-energy measurements by the repetition rate multiplication method with a special Fermi chopper, and polarization analysis with He spin filters. 4SEASONS is now under construction and will be ready to use in December 2008. In this paper, we show the design of 4SEASONS and current status of its construction.

Chopper-type neutron inelastic spectrometer 4SEASONS at MLF, J-PARC

Kajimoto, Ryoichi; Yokoo, Tetsuya*; Nakamura, Mitsutaka; Nakajima, Kenji; Inamura, Yasuhiro; Takahashi, Nobuaki; Maruyama, Ryuji; Soyama, Kazuhiko; Mizuno, Fumio; Shibata, Kaoru; et al.

no journal, , 

no abstracts in English

Comprehensive benchmark calculations of the latest version of the PHITS code

Iwamoto, Yosuke; Sato, Tatsuhiko; Hashimoto, Shintaro; Ogawa, Tatsuhiko; Furuta, Takuya; Abe, Shinichiro; Kai, Takeshi; Matsuda, Norihiro; Hosoyamada, Ryuji*; Niita, Koji*

no journal, , 

Particles and Heavy Ions Transport code System (PHITS) is used for various purposes such as accelerator shielding design, medical physics calculations, and so on. In this study, we performed benchmark calculations for particle production cross sections (47 cases), neutron transport (6 cases) and electro-magnetic cascade (12 cases). For calculations of particle production cross sections, PHITS reproduced the experimental data for high-energy particle incident reactions with energies of above 100 MeV. On the other hands, PHITS did not reproduce the data for low-energy incident reactions due to outside of scope for the intra nuclear cascade model INCL4. We will incorporate the evaluated nuclear data library JENDL4.0/HE with PHITS to solve the problem. For calculations of electro-magnetic cascade, PHITS reproduced the data well. As a result, we validated the accuracy of PHITS calculations for various applied area and obtained guidelines for effective improvement of PHITS.