Development of an electron spin resonance spectroscopy code for measuring carbonate radicals in tooth enamel and verification of its practicality using irradiated Japanese macaque teeth

Yamashita, Takuma*; Hayashi, Teppei*; Mitsuyasu, Yusuke*; Ono, Kenta*; Iwami, Satone*; Kino, Yasushi*; Sekine, Tsutomu*; Oka, Toshitaka; Takahashi, Atsushi*; Shimizu, Yoshinaka*; et al.

International Journal of Radiation Biology, 102(7), p.880 - 887, 2026/07

https://doi.org/10.1080/09553002.2025.2510676

no abstracts in English

Development of the diagnostic and transport beamline for the muon linac low-velocity section

Nakazawa, Yuga*; Cicek, E.*; Ishida, Katsuhiko*; Futatsukawa, Kenta*; Shimomura, Koichiro*; Otani, Masashi*; Kimura, Masato*; Kamioka, Shusei*; Yamazaki, Takayuki*; Mibe, Tsutomu*; et al.

Proceedings of 16th International Particle Accelerator Conference (IPAC25) (Internet), p.1163 - 1166, 2025/11

https://doi.org/10.18429/JACoW-IPAC2025-TUPS156

At the Japan Proton Accelerator Research Complex (J-PARC), low-emittance muon beams with a linear accelerator (linac) are proposed as a new approach to precisely measure the anomalous magnetic moment and electric dipole moment of the muon. Low-emittance muon beams can also be employed as new probes for non-destructive imaging techniques to see through structures. In the low-velocity section of the muon linac, a radio-frequency quadrupole linac (RFQ) and an interdigital H-mode drift tube linac (IH-DTL) are used to accelerate muons to = v/c = 0.08 and 0.28, respectively, at an operating frequency of 324 MHz. To reduce construction costs, the IH-DTL employs the alternating phase focusing (APF) method, which uses the transverse focusing force derived from the RF electric field. Because the APF method limits the transverse and longitudinal acceptances simultaneously, careful beam diagnostics and commissioning are essential to suppress the emittance growth derived from beam mismatches. As a result of the beam simulation, by conducting appropriate beam matching, the normalized rms emittance of 0.3 -mm-mrad and the transmission to the downstream detector of 97% was obtained. In this paper, the results of the tracking simulation and the development status of the diagnostic and transport beamlines in the low-velocity section are described.

Improvement of thermal insulation materials for the expansion joint of the steam plumbing for Reprocessing Plants

Komatsu, Seiji; Nishida, Tetsuro; Kawasaki, Ichio; Gunji, Hikaru; Nishino, Shohei; Kambara, Takashi*; Miura, Hirohito*; Suzuki, Takaichi*; Kinoshita, Masato*; Kanei, Tatsuya*

Nihon Hozen Gakkai Dai-21-Kai Gakujutsu Koenkai Yoshishu, 5 Pages, 2025/07

Steam used for process and air conditioning in each facility at the Nuclear Fuel Cycle Engineering Institute is generated by a water tube boiler installed in the Institute's central control room and supplied to each facility via underground trenches. There are three steam supply pipelines (A, B, and C) to each facility, with two of these (A and B) designated for the reprocessing facility. The steam pipelines, including expansion joints and steam traps, are covered with insulation. The two steam pipelines for the reprocessing facility (A and B) are laid parallel, creating a structure that makes inspection and maintenance difficult. In particular, the expansion joints are spaced very closely between the A and B lines, making insulation removal difficult, which has been a challenge in performing visual inspections of the expansion joint bodies. This paper reports on the features and effects of an improved insulation system designed to allow for easy removal and installation.

Competition between mass-symmetric and asymmetric fission modes in Md produced in the He + Es reaction

Nishio, Katsuhisa; Hirose, Kentaro; Makii, Hiroyuki; Orlandi, R.; Kean, K. R.*; Tsukada, Kazuaki; Toyoshima, Atsushi*; Asai, Masato; Sato, Tetsuya; Chiera, N. M.*; et al.

Physical Review C, 111(4), p.044609_1 - 044609_12, 2025/04

https://doi.org/10.1103/PhysRevC.111.044609

Improved multicomponent analysis method for electron spin resonance spectra of gamma-irradiated tooth enamel

Yamashita, Takuma*; Iwami, Satone*; Mitsuyasu, Yusuke*; Ono, Kenta*; Oka, Toshitaka; Takahashi, Atsushi*; Kino, Yasushi*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.

KEK Proceedings 2024-6, p.85 - 90, 2024/12

https://lib-extopc.kek.jp/preprints/PDF/2024/2425/2425006.pdf

To clarify the radiation effects of the accident at the TEPCO's Fukushima Daiichi NPP on living organisms, it is important to accurately estimate the dose to each individual. We have developed a multi-component analysis program using random number optimization to extract only the components derived from carbonate radicals from the ESR spectra.

Application of the spectral determination method to liquid scintillation spectra

Oshima, Masumi*; Goto, Jun*; Hayakawa, Takehito*; Shinohara, Hirofumi*; Suzuki, Katsuyuki*; Sano, Yuichi*; Asai, Masato; Haraga, Tomoko

Journal of Nuclear Science and Technology, 61(7), p.871 - 882, 2024/07

https://doi.org/10.1080/00223131.2023.2282552

Previously we reported a simple algorithmic method of spectral determination method (SDM), which is based on the first principle that a -ray spectrum obtained for a sample is a linear superposition of individual spectra of the radioactive nuclides included in the sample and demonstrated that the method is valid for -ray determination. Here we apply it to the spectra obtained by liquid scintillation counter (LSC). In LSC measurements quenching is generally observed and we at first developed its correction method to standard spectra. The SDM code reported in the previous investigation is used to analyze the LSC spectra. Based on the analyses done by using the measured spectra, we concluded that the SDM method is valid in the LSC spectra similarly to the -ray spectra studied in the previous investigation.

Estimation of external dose for wild Japanese macaques captured in Fukushima prefecture; Decomposition of electron spin resonance spectrum

Mitsuyasu, Yusuke*; Oka, Toshitaka; Takahashi, Atsushi*; Kino, Yasushi*; Okutsu, Kenichi*; Sekine, Tsutomu*; Yamashita, Takuma*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; et al.

Radiation Protection Dosimetry, 199(14), p.1620 - 1625, 2023/09

https://doi.org/10.1093/rpd/ncad146

We have been conducting dose assessments for Japanese macaques captured in Fukushima to reveal radiobiological effects on the low-dose expose animals. To accurately determine the external exposure dose, it is desirable to examine the analysis of the CO radical intensity. We examined ESR spectra of teeth of 10 macaques captured in Fukushima by two spectrum-decomposition algorithms.

Optimization of mercury flow with microbubbles in the target-vessel design by means of machine learning

Kogawa, Hiroyuki; Futakawa, Masatoshi; Haga, Katsuhiro; Tsuzuki, Takayuki*; Murai, Tetsuro*

JAEA-Technology 2022-023, 128 Pages, 2022/11

JAEA-Technology-2022-023.pdf:9.0MB

In a mercury target of the J-PARC (Japan Proton Accelerator Research Complex), pulsed proton beams repeatedly bombard the flowing mercury which is confined in a stainless-steel vessel (target vessel). Cavitation damage caused by the propagation of the pressure waves is a factor of the life of the target vessel. As a measure to reduce damages, we developed a bubbler to inject the gas microbubbles into the flowing mercury, which can reduce the pressure waves. To operate the mercury target vessel stably with the 1 MW high-intensity proton beams, further reduction of the damage is required. The bubbler setting position should be closer to the beam window to increase the bubble population, which could enhance the reduction effect on the pressure waves and damage. However, the space at the beam window of the target vessel is restricted. The bubbler design and setting position as well as the vane design for the mercury flowing pattern are optimized by means of a machine learning technique to get more suitable bubble distribution, increasing in bubble population and optimizing bubble size nearby the beam window of the target vessel. The results of CFD analyses performed with 1000 cases were used for machine learning. Since the flow rate of mercury affects the temperature of the target vessel, this was used for the constraint condition. As a result, we found a design of mercury target vessel that can increase the bubble population by ca. 20% higher than the current design.

A Study on accuracy of analysis of the radiation-induced component in the ESR spectra of teeth

Mitsuyasu, Yusuke*; Oka, Toshitaka; Takahashi, Atsushi*; Kino, Yasushi*; Okutsu, Kenichi*; Sekine, Tsutomu*; Yamashita, Takuma*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; et al.

KEK Proceedings 2022-2, p.120 - 125, 2022/11

https://lib-extopc.kek.jp/preprints/PDF/2022/2225/2225002.pdf

We investigate the effect of sample's anisotropy and measurement condition to obtain the higher reproducibility for the shape of the ESR spectrum and the intensity of CO radical.

Completion of waste removal work from the hot cell of Operation Testing Laboratory in Tokai Reprocessing Plant

Goto, Yuichi; Suzuki, Yoshimasa; Horigome, Kazushi; Miyamoto, Toshihiko*; Usui, Masato*; Mori, Eito*; Kuno, Takehiko

JAEA-Technology 2022-005, 42 Pages, 2022/07

JAEA-Technology-2022-005.pdf:4.48MB

Radioactive wastes were generated and stored in the hot cell of Operation Testing Laboratory of Tokai Reprocessing Plant due to the experiments related to the reprocessing technology development from 1974 to 2014. Waste removal work was strengthened by the shift work in the past, however another wastes were generated by the equipment dismantling. From 2006, an improved waste removal method was established by using bag-out technique and wastes were taken from the glove-box connected to the hot cell. The removal period, estimated from the conventional method using Cask No. 10, was reduced from 14 to 5 years. From 2016, upgrade of worker's awareness including related departments was performed by various software and hardware improvements. Also, the worker's skills were improved and equipment in Cask No.10 was checked for preventive maintenance. The prevention measures for past troubles were discussed with Radiation Control Department. In addition, transportation schedule including safety operation with Transportation Department and Waste Receiving Department was optimized to maintain the waste removal cycle. The removal period was reduced from 5 to 3 years by the above efforts. Finally, the work was completed in March 2020.