Fabrication progress of the prototype spoke cavity for the JAEA-ADS linac

Tamura, Jun; Kondo, Yasuhiro; Yee-Rendon, B.; Meigo, Shinichiro; Maekawa, Fujio; Kako, Eiji*; Umemori, Kensei*; Sakai, Hiroshi*; Domae, Takeshi*

Journal of Physics; Conference Series, 2687(5), p.052008_1 - 052008_6, 2024/01

https://doi.org/10.1088/1742-6596/2687/5/052008

Effect of Mn substitution on the electronic structure for Mn-doped indium-tin oxide films studied by soft and hard X-ray photoemission spectroscopy

Otsuki, Daiki*; Ishida, Tatsuhiro*; Tsutsumi, Naoya*; Kobayashi, Masaki*; Inagaki, Kodai*; Yoshida, Teppei*; Takeda, Yukiharu; Fujimori, Shinichi; Yasui, Akira*; Kitagawa, Saiki*; et al.

Physical Review Materials (Internet), 7(12), p.124601_1 - 124601_6, 2023/12

https://doi.org/10.1103/PhysRevMaterials.7.124601

Stabilization of post-experiment nuclear materials in Plutonium Fuel Research Facility

Sato, Takumi; Otobe, Haruyoshi; Morishita, Kazuki; Marufuji, Takato; Ishikawa, Takashi; Fujishima, Tadatsune; Nakano, Tomoyuki

JAEA-Technology 2023-016, 41 Pages, 2023/09

JAEA-Technology-2023-016.pdf:2.74MB

This report summarizes the results of the stabilization treatments of post-experiment nuclear materials in Plutonium Fuel Research Facility (PFRF) from August 2018 to March 2021. Based on the management standards for nuclear materials enacted after the contamination accident that occurred at PFRF on June 6, 2017, the post-experiment nuclear materials containing plutonium (Pu): samples mixed with organic substances that cause an increase in internal pressure due to radiolysis (including X-ray diffraction samples mixed with epoxy resin and plutonium powder which caused contamination accidents), carbides and nitrides samples which is reactive in air, and chloride samples which may cause corrosion of storage containers, were selected as targets of the stabilization. The samples containing organic materials, carbides and nitrides were heated in an air flow at 650 C and 950 C for 2 hours respectively to remove organic materials and convert uranium (U) and Pu into oxides. U and Pu chlorides in LiCl-KCl eutectic melt were reduced and extracted into liquid Cd metal by a reaction with lithium (Li) -cadmium (Cd) alloy and converted to U-Pu-Cd alloy at 500 C or higher. All of the samples were stabilized and stored at PFRF. We hope that the contents of this report will be utilized to consider methods for stabilizing post experiment nuclear materials at other nuclear fuel material usage facilities.

One-dimensional band structure in quasi-two-dimensional -MoO revealed by angle-resolved photoelectron spectroscopy and first-principles calculation

Sumida, Kazuki; Higaki, Sota*; Sato, Hitoshi*; Tsuru, Daichi*; Miyamoto, Koji*; Okuda, Taichi*; Kuroiwa, Yoshihiro*; Moriyoshi, Chikako*; Takase, Koichi*; Oguchi, Tamio*; et al.

Journal of the Physical Society of Japan, 92(8), p.084706_1 - 084706_6, 2023/08

https://doi.org/10.7566/JPSJ.92.084706

Intruder configurations in Ne at the transition into the island of inversion; Detailed structure study of Ne

Wang, H.*; Yasuda, Masahiro*; Kondo, Yosuke*; Nakamura, Takashi*; Tostevin, J. A.*; Ogata, Kazuyuki*; Otsuka, Takaharu*; Poves, A.*; Shimizu, Noritaka*; Yoshida, Kazuki; et al.

Physics Letters B, 843, p.138038_1 - 138038_9, 2023/08

https://doi.org/10.1016/j.physletb.2023.138038

Detailed -ray spectroscopy of the exotic neon isotope Ne has been performed using the one-neutron removal reaction from Ne. Based on an analysis of parallel momentum distributions, a level scheme with spin-parity assignments has been constructed for Ne and the negative-parity states are identified for the first time. The measured partial cross sections and momentum distributions reveal a significant intruder p-wave strength providing evidence of the breakdown of the N = 20 and N = 28 shell gaps. Only a weak, possible f-wave strength was observed to bound final states. Large-scale shell-model calculations with different effective interactions do not reproduce the large p-wave and small f-wave strength observed experimentally, indicating an ongoing challenge for a complete theoretical description of the transition into the island of inversion along the Ne isotopic chain.

Measurement of double-differential neutron yields for iron, lead, and bismuth induced by 107-MeV protons for research and development of accelerator-driven systems

Iwamoto, Hiroki; Nakano, Keita; Meigo, Shinichiro; Satoh, Daiki; Iwamoto, Yosuke; Sugihara, Kenta*; Nishio, Katsuhisa; Ishi, Yoshihiro*; Uesugi, Tomonori*; Kuriyama, Yasutoshi*; et al.

EPJ Web of Conferences, 284, p.01023_1 - 01023_4, 2023/05

https://doi.org/10.1051/epjconf/202328401023

For accurate prediction of neutronic characteristics for accelerator-driven systems (ADS) and a source term of spallation neutrons for reactor physics experiments for the ADS at Kyoto University Critical Assembly (KUCA), we have launched an experimental program to measure nuclear data on ADS using the Fixed Field Alternating Gradient (FFAG) accelerator at Kyoto University. As part of this program, the proton-induced double-differential thick-target neutron-yields (TTNYs) and cross-sections (DDXs) for iron, lead, and bismuth have been measured with the time-of-flight (TOF) method. For each measurement, the target was installed in a vacuum chamber on the beamline and bombarded with 107-MeV proton beams accelerated from the FFAG accelerator. Neutrons produced from the targets were detected with stacked, small-sized neutron detectors for several angles from the incident beam direction. The TOF spectra were obtained from the detected signals and the FFAG kicker magnet's logic signals, where gamma-ray events were eliminated by pulse shape discrimination. Finally, the TTNYs and DDXs were obtained from the TOF spectra by relativistic kinematics. The measured TTNYs and DDXs were compared with calculations by the Monte Carlo transport code PHITS with its default physics model of INCL version 4.6 combined with GEM and those with the JENDL-4.0/HE nuclear data library.

Measurement of 107-MeV proton-induced double-differential thick target neutron yields for Fe, Pb, and Bi using a fixed-field alternating gradient accelerator at Kyoto University

Iwamoto, Hiroki; Nakano, Keita; Meigo, Shinichiro; Satoh, Daiki; Iwamoto, Yosuke; Sugihara, Kenta; Nishio, Katsuhisa; Ishi, Yoshihiro*; Uesugi, Tomonori*; Kuriyama, Yasutoshi*; et al.

Journal of Nuclear Science and Technology, 60(4), p.435 - 449, 2023/04

https://doi.org/10.1080/00223131.2022.2115423

Double-differential thick target neutron yields (TTNYs) for Fe, Pb, and Bi targets induced by 107-MeV protons were measured using the fixed-field alternating gradient accelerator at Kyoto University for research and development of accelerator-driven systems (ADSs) and fundamental ADS reactor physics research at the Kyoto University Critical Assembly (KUCA). Note that TTNYs were obtained with the time-of-flight method using a neutron detector system comprising eight neutron detectors; each detector has a small NE213 liquid organic scintillator and photomultiplier tube. The TTNYs obtained were compared with calculation results using Monte Carlo-based spallation models (i.e., INCL4.6/GEM, Bertini/GEM, JQMD/GEM, and JQMD/SMM/GEM) and the evaluated high-energy nuclear data library, i.e., JENDL-4.0/HE, implemented in the particle and heavy iontransport code system (PHITS). All models, including JENDL-4.0/HE, failed to predict high-energy peaks at a detector angle of 5. Comparing the energy- and angle-integrated spallation neutron yields at energies of 20 MeV estimated using the measured TTNYs and the PHITS indicated that INCL4.6/GEM would be suitable for the Monte Carlo transport simulation of ADS reactor physics experiments at the KUCA.

A Phoswich alpha/beta detector for monitoring in the site of Fukushima Daiichi Nuclear Power Station

Morishita, Yuki; Takasaki, Koji; Kitayama, Yoshiharu; Tagawa, Akihiro; Shibata, Takuya; Hoshi, Katsuya; Kaneko, Junichi*; Higuchi, Mikio*; Oura, Masatoshi*

Radiation Measurements, 160, p.106896_1 - 106896_10, 2023/01

https://doi.org/10.1016/j.radmeas.2022.106896

This study proposes a newly developed phoswich alpha/beta detector that can discriminate alpha and beta particles emitted from the alpha and beta contaminations in the FDNPS site. The phoswich alpha/beta detector is made up of two layers of scintillators that detect alpha and beta particles. The pulse shape discrimination (PSD) method was used to detect alpha particles in high beta particle and high gamma-ray (comparable to gamma-ray dose rate near the FDNPS reactor building) environments. Due to a 23.3% full width at half maximum (FWHM) energy resolution for alpha particles, the detector can be used to distinguish between nuclear fuel materials such as plutonium and its radon progeny (Po-214). Moreover, the detector could distinguish alpha particles from Cs gamma rays with a dose rate background up to 9.0 mSv/h. It is the first to demonstrate that the developed phoswich detector can be used to discriminate and measure alpha and beta particles of the actual contaminated FDNPS samples.

Materials science and fuel technologies of uranium and plutonium mixed oxide

Kato, Masato; Machida, Masahiko; Hirooka, Shun; Nakamichi, Shinya; Ikusawa, Yoshihisa; Nakamura, Hiroki; Kobayashi, Keita; Ozawa, Takayuki; Maeda, Koji; Sasaki, Shinji; et al.

Materials Science and Fuel Technologies of Uranium and Plutonium mixed Oxide, 171 Pages, 2022/10

https://doi.org/10.1201/9781003298205

Innovative and advanced nuclear reactors using plutonium fuel has been developed in each country. In order to develop a new nuclear fuel, irradiation tests are indispensable, and it is necessary to demonstrate the performance and safety of nuclear fuels. If we can develop a technology that accurately simulates irradiation behavior as a technology that complements the irradiation test, the cost, time, and labor involved in nuclear fuel research and development will be greatly reduced. And safety and reliability can be significantly improved through simulation of nuclear fuel irradiation behavior. In order to evaluate the performance of nuclear fuel, it is necessary to know the physical and chemical properties of the fuel at high temperatures. And it is indispensable to develop a behavior model that describes various phenomena that occur during irradiation. In previous research and development, empirical methods with fitting parameters have been used in many parts of model development. However, empirical techniques can give very different results in areas where there is no data. Therefore, the purpose of this study is to construct a scientific descriptive model that can extrapolate the basic characteristics of fuel to the composition and temperature, and to develop an irradiation behavior analysis code to which the model is applied.

Partial breakdown of translation symmetry at a structural quantum critical point associated with a ferroelectric soft mode

Ishii, Yui*; Yamamoto, Arisa*; Sato, Naoki*; Nambu, Yusuke*; Kawamura, Seiko; Murai, Naoki; Ohara, Koji*; Kawaguchi, Shogo*; Mori, Takao*; Mori, Shigeo*

Physical Review B, 106(13), p.134111_1 - 134111_7, 2022/10

https://doi.org/10.1103/PhysRevB.106.134111