First observation of O

Kondo, Yosuke*; Achouri, N. L.*; Al Falou, H.*; Atar, L.*; Aumann, T.*; Baba, Hidetada*; Boretzky, K.*; Caesar, C.*; Calvet, D.*; Chae, H.*; et al.

Nature, 620(7976), p.965 - 970, 2023/08

https://doi.org/10.1038/s41586-023-06352-6

no abstracts in English

Multiple mechanisms in proton-induced nucleon removal at 100 MeV/nucleon

Pohl, T.*; Sun, Y. L.*; Obertelli, A.*; Lee, J.*; Gmez-Ramos, M.*; Ogata, Kazuyuki*; Yoshida, Kazuki; Cai, B. S.*; Yuan, C. X.*; Brown, B. A.*; et al.

Physical Review Letters, 130(17), p.172501_1 - 172501_8, 2023/04

https://doi.org/10.1103/PhysRevLett.130.172501

We report on the first proton-induced single proton- and neutron-removal reactions from the neutron deficient O nucleus with large Fermi-surface asymmetry at 100 MeV/nucleon. Our results provide the first quantitative contributions of multiple reaction mechanisms including the quasifree knockout, inelastic scattering, and nucleon transfer processes. It is shown that the inelastic scattering and nucleon transfer, usually neglected at such energy regime, contribute about 50% and 30% to the loosely bound proton and deeply bound neutron removal, respectively.

Recent improvements of the Particle and Heavy Ion Transport code System; PHITS version 3.33

Sato, Tatsuhiko; Iwamoto, Yosuke; Hashimoto, Shintaro; Ogawa, Tatsuhiko; Furuta, Takuya; Abe, Shinichiro; Kai, Takeshi; Matsuya, Yusuke; Matsuda, Norihiro; Hirata, Yuho; et al.

Journal of Nuclear Science and Technology, 9 Pages, 2023/00

https://doi.org/10.1080/00223131.2023.2275736

The Particle and Heavy Ion Transport code System (PHITS) is a general-purpose Monte Carlo radiation transport code that can simulate the behavior of most particle species with energies up to 1 TeV (per nucleon for ions). Its new version, PHITS3.31, was recently developed and released to the public. In the new version, the compatibility with high-energy nuclear data libraries and the algorithm of the track-structure modes have been improved. In this paper, we summarize the upgraded features of PHITS3.31 with respect to the physics models, utility functions, and application software introduced since the release of PHITS3.02 in 2017.

Non-Hookean large elastic deformation in bulk crystalline metals

Xu, S.*; Odaira, Takumi*; Sato, Shunsuke*; Xu, X.*; Omori, Toshihiro*; Harjo, S.; Kawasaki, Takuro; Seiner, H.*; Zoubkov, K.*; Murakami, Yasukazu*; et al.

Nature Communications (Internet), 13, p.5307_1 - 5307_8, 2022/09

https://doi.org/10.1038/s41467-022-32930-9

Improvement of the Simplified Decommissioning Cost Estimation Code for Nuclear Facilities (DECOST)

Takahashi, Nobuo; Kubota, Shintaro; Takiya, Hiroaki; Sakaba, Ryosuke*; Sato, Koichi; Shichi, Ryo

JAEA-Testing 2021-002, 106 Pages, 2022/01

JAEA-Testing-2021-002.pdf:2.08MB

The Japan Atomic Energy Agency has various nuclear facilities such as reactor facilities and reprocessing facilities. Some aged facilities will be decommissioned after their original functions ended, and it is necessary to evaluate their decommissioning cost to formulate the initial decommissioning plans and the final decommissioning plans. We have developed an evaluation method called DECOST that can efficiently calculate the decommissioning cost in a short time based on factors such as features and similarity of the facilities and dismantling methods. The decommissioning of nuclear facilities has been implemented and new achievements and findings have been reported since the development of DECOST. These findings were reflected in DECOST. In consideration of the needs of DECOST users, DECOST has been improved so that the cost of dismantling the facility can be divided into the cost of releasing the controlled area and the cost of dismantling the facility building after the release of the controlled area. This report shows the improvement of DECOST, the concept of resetting the evaluation coefficient used in the cost evaluation formula, and the validity of the evaluation coefficient after resetting. In addition, the evaluation procedure of the improved DECOST is described, since the evaluation items and evaluation contents were partially changed due to the improvement.

Variation in formation and migration of self-interstitial atom clusters in electron irradiated copper with material purity and specimen preparation method

Sato, Yuki*; Abe, Yosuke; Okubo, Kenji*; Tanioka, Takashi*

Philosophical Magazine, 102(12), p.1152 - 1172, 2022/00

https://doi.org/10.1080/14786435.2022.2042610

Using in situ observation with high-voltage electron microscope, one-dimensional (1D) migration of self-interstitial atom (SIA) clusters under electron irradiation at 300 K was surveyed for copper materials of five nominal purities and TEM specimens prepared with three methods. In standard (STD) specimens that were prepared through cold rolling and annealing in the vacuum, formation and 1D migration of SIA clusters did not depend much on the nominal purity. In non-annealed (NA) specimens, prepared from high purity materials through mechanical processing and electropolishing, defect structure was coarser than in STD specimens. Results of bulk annealing (BA) specimens showed that annealing of as-received block material had minor effects. Above results were discussed based on the hypothesis that impurity atoms existing in as-received materials and those induced by annealing act as traps for SIA clusters.

Probabilistic risk assessment of solar particle events considering the cost of countermeasures to reduce the aviation radiation dose

Fujita, Moe*; Sato, Tatsuhiko; Saito, Susumu*; Yamashiki, Yosuke*

Scientific Reports (Internet), 11, p.17091_1 - 17091_9, 2021/09

https://doi.org/10.1038/s41598-021-95235-9

Radiation exposure to flight crews and passengers, which is called aviation exposure, is an important topic in radiological protection, particularly due to solar energetic particles (SEP). We assessed the risks against the counter measure costs to reduce SEP doses and dose rates for eight flight routes during five ground level enhancements (GLE). A four-dimensional dose-rate database developed by the Warning System for Aviation Exposure to Solar Energetic Particles, WASAVIES, was employed in the SEP dose evaluation. Our calculations suggest that GLE that is enough to request a change in flight conditions occurs once per 47 and 17 years respectively, in the case of following the dose and dose-rate regulations. The annual risks against the counter measure costs are up to around 1500 USD per long-distance and high-latitude flight.

Analysis and mapping of detailed inner information of crystalline grain by wavelength-resolved neutron transmission imaging with individual Bragg-dip profile-fitting analysis

Sakurai, Yosuke*; Sato, Hirotaka*; Adachi, Nozomu*; Morooka, Satoshi; Todaka, Yoshikazu*; Kamiyama, Takashi*

Applied Sciences (Internet), 11(11), p.5219_1 - 5219_17, 2021/06

https://doi.org/10.3390/app11115219

Feasibility study of PGAA for boride identification in simulated melted core materials

Tsuchikawa, Yusuke; Abe, Yuta; Oishi, Yuji*; Kai, Tetsuya; Toh, Yosuke; Segawa, Mariko; Maeda, Makoto; Kimura, Atsushi; Nakamura, Shoji; Harada, Masahide; et al.

JPS Conference Proceedings (Internet), 33, p.011074_1 - 011074_6, 2021/03

https://doi.org/10.7566/JPSCP.33.011074

In the decommissioning of the Fukushima-Daiichi (1F) Nuclear Power Plant, it is essential to understand characteristics of the melted core materials. The estimation of boride in the real debris is of great importance to develop safe debris removal plans. Hence, it is required to investigate the amount of boron in the melted core materials with nondestructive methods. Prompt gamma-ray activation analysis (PGAA) is one of the useful techniques to determine the amount of borides by means of the 478 keV prompt gamma-ray from neutron absorption reaction of boron. Moreover, it is well known that the width of the 478 keV gamma-ray peak is typically broadened due to the Doppler effect. The degree of the broadening is affected by coexisting materials, and can be recognized by the width of the prompt gamma-ray peak. As a feasibility study, the prompt gamma-ray from boride samples were measured using the ANNRI, NOBORU, and RADEN beamlines at the Materials and Life Science Experimental Facility (MLF) of Japan Proton Accelerator Complex (J-PARC).

High temperature gas-cooled reactors

Takeda, Tetsuaki*; Inagaki, Yoshiyuki; Aihara, Jun; Aoki, Takeshi; Fujiwara, Yusuke; Fukaya, Yuji; Goto, Minoru; Ho, H. Q.; Iigaki, Kazuhiko; Imai, Yoshiyuki; et al.

High Temperature Gas-Cooled Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.5, 464 Pages, 2021/02

https://doi.org/10.1016/C2018-0-05383-9

As a general overview of the research and development of a High Temperature Gas-cooled Reactor (HTGR) in JAEA, this book describes the achievements by the High Temperature Engineering Test Reactor (HTTR) on the designs, key component technologies such as fuel, reactor internals, high temperature components, etc., and operational experience such as rise-to-power tests, high temperature operation at 950C, safety demonstration tests, etc. In addition, based on the knowledge of the HTTR, the development of designs and component technologies such as high performance fuel, helium gas turbine and hydrogen production by IS process for commercial HTGRs are described. These results are very useful for the future development of HTGRs. This book is published as one of a series of technical books on fossil fuel and nuclear energy systems by the Power Energy Systems Division of the Japan Society of Mechanical Engineers.