HTTR1次ヘリウム循環機フィルタの差圧上昇事象,1; 差圧上昇事象の原因調査

根本 隆弘; 荒川 了紀; 川上 悟; 長住 達; 横山 佳祐; 渡部 雅; 大西 貴士; 川本 大樹; 古澤 孝之; 猪井 宏幸; et al.

JAEA-Technology 2023-005, 33 Pages, 2023/05

JAEA-Technology-2023-005.pdf:5.25MB

HTTR (High Temperature engineering Test Reactor) RS-14サイクルの原子炉出力降下において、ヘリウムガス循環機のフィルタ差圧が上昇傾向となった。この原因を調査するため、1次ヘリウム純化設備のガス循環機の分解点検等を実施した結果、ガス循環機内のシリコンオイルミストがチャコールフィルタの性能低下で捕集できなくなり、1次系統に混入したためと推定された。今後は、フィルタ交換を実施するとともに、さらなる調査を進め、再発防止対策を策定する予定である。

Raman identification and characterization of chemical components included in simulated nuclear fuel debris synthesized from uranium, stainless steel, and zirconium

日下 良二; 熊谷 友多; 渡邉 雅之; 佐々木 隆之*; 秋山 大輔*; 佐藤 修彰*; 桐島 陽*

Journal of Nuclear Science and Technology, 60(5), p.603 - 613, 2023/05

https://doi.org/10.1080/00223131.2022.2128460

Raman spectroscopy is a powerful technique for studying nuclear materials. However, it has been scarcely utilized for nuclear fuel debris. Here, we present a Raman study of several types of simulated nuclear debris synthesized from uranium, stainless steel, and zirconium to identify and characterize chemical components included in the simulated debris. Raman spectroscopy sensitively identified many kinds of chemical components: cubic UO, UO, (Fe,Cr)UO (iron-chromium uranate), spinel oxides, monoclinic ZrO, tetragonal ZrO, and ZrO. Some details concerning the chemical states of each component included in the simulated debris were obtained (e.g., spinel oxides were suggested to consist of Fe, Cr, Ni, Zr, and U). The results obtained here will be helpful in the Raman analysis of actual nuclear debris, such as that in the Fukushima-Daiichi nuclear power plants.

Short-range spin order in paramagnetic AgCrSe

中村 惇平*; 川北 至信; 岡部 博孝*; Li, B.*; 下村 浩一郎*; 末益 崇*

Journal of Physics and Chemistry of Solids, 175, p.111199_1 - 111199_8, 2023/04

https://doi.org/10.1016/j.jpcs.2022.111199

Muon spin rotation (SR) experiments were performed to directly investigate the temperature dependence of the short-range order or correlations of chromium spins in the paramagnetic phase of AgCrSe. The detailed investigation of the SR spectra over a wide temperature range from low to high temperatures revealed that the short-range spin correlations developed below about 184 K. It also confirmed no short-range correlations at high temperatures, which had been controversial in previous quasi-elastic neutron scattering studies. In addition, the muon spin relaxation was qualitatively changed and showed large missing asymmetry below about 89 K, where the correlation clearly implied short-range spin order. There could be a preparative phenomenon of the phase transition or an anisotropic short-range spin correlation.

海外炉を用いた中性子照射試験,1; キャプセル温度制御システムを用いた照射試験の検討(共同研究)

高部 湧吾; 大塚 紀彰; 冬島 拓実; 佐谷戸 夏紀; 井上 修一; 森田 寿; Jaroszewicz, J.*; Migdal, M.*; 小沼 勇一; 飛田 正浩*; et al.

JAEA-Technology 2022-040, 45 Pages, 2023/03

JAEA-Technology-2022-040.pdf:6.61MB

中性子照射場として中核を担ってきた材料試験炉(Japan Materials Testing Reactor: JMTR)の廃止に伴い、軽水炉の一層の安全性、信頼性・効率性向上のための技術開発や革新的な原子炉開発に必要な国内照射場が喪失され、照射試験炉の運転技術や照射技術の継承や人材育成も困難な状況となった。こうした課題に対処するため、代替手段として中性子照射場を海外炉に求めた照射試験の実施に係る検討を行った。「ポーランド国立原子力研究センターと日本原子力研究開発機構との間の試験研究炉の研究開発のための共同研究取決め」に基づきポーランド国立原子力研究センター(NCBJ)が所有するMARIA炉(出力30MW)を中性子照射場として、JMTRの有する照射技術の一つである温度制御システムを導入した照射試験の実施可否を検討した。その結果、JMTRの設計・製作基準に則って製作済であったキャプセルに対し改造を施すことで照射試験の実現が可能である見通しが得られた。改造後に浸透探傷検査、絶縁導通試験及びキャプセルの使用温度である室温300Cの範囲における動作試験等を実施し、良好な結果が得られ、MARIA炉への輸送前準備を完了した。

Fact-finding survey on the competencies and literacy of radiological technologists regarding radiation disasters

新井 知大*; 村田 歩*; 渡邊 雄一*; 石原 敏裕*; 深水 良哉*; 武田 聡司*; 江端 清和*; 渡邊 裕貴; 高島 良生*; 金子 順一*

Journal of X-Ray Science and Technology, 31(2), p.237 - 245, 2023/03

https://doi.org/10.3233/XST-221341

診療放射線技師は、放射線に関する専門的な教育を受けており、医療領域における放射線業務に従事するとともに、患者が抱える放射線被ばくに関する不安の軽減に努めるリスクコミュニケーターとしての役割も担っている。また、2011年3月の福島第一原子力発電所事故の際、避難者の体表面及び携行物品の放射性物質の汚染検査要員として、全国各地域の診療放射線技師が派遣された。本研究では、国立病院機構に所属する診療放射線技師を対象として放射線災害に関する知識及び意識に関する実態調査を実施することにより、放射線災害に関する診療放射線技師のリテラシー及びコンピテンシーを明らかにした。また、日本の診療放射線技師の放射線災害に関する知識及び意識を、原子力発電所の立地地域(隣接地域含む)と非立地地域で比較し、放射線災害に対応可能な診療放射線技師の人材育成の在り方について検討した。

令和3年度原子力発電所周辺における航空機モニタリング(受託研究)

普天間 章; 眞田 幸尚; 長久保 梓; 川崎 義晴*; 岩井 毅行*; 平賀 祥吾*; 萩野谷 仁*; 松永 祐樹*; 圷 雄一郎*; 卜部 嘉*; et al.

JAEA-Technology 2022-027, 148 Pages, 2023/02

JAEA-Technology-2022-027.pdf:19.64MB

2011年3月11日に発生した東北地方太平洋沖地震による津波に起因した東京電力福島第一原子力発電所事故によって、大量の放射性物質が周辺環境に飛散した。事故直後より、放射線の分布を迅速かつ広範囲に測定する手法として、航空機等を用いた空からの測定方法が適用されている。日本原子力研究開発機構では、有人ヘリコプターを使用した航空機モニタリングを福島第一原子力発電所周辺において継続的に実施してきた。本報告書では、令和3年度に実施した福島第一原子力発電所周辺におけるモニタリング結果について取りまとめると共に、過去のモニタリング結果から空間線量率等の変化量を評価し、その変化要因について考察した。また、航空機モニタリングによる空間線量率の計算精度向上に資するために、航空機モニタリングデータを用いて地形の起伏を考慮に入れた解析を行った。地形の起伏を考慮に入れる前後での解析結果を比較し、本手法による精度向上効果を評価した。さらに、空気中のラドン子孫核種の弁別手法を測定結果に適用して、空気中のラドン子孫核種が航空機モニタリングに与える影響について評価した。

Water contents in aggregates and cement pastes determined by gravimetric analysis and prompt -ray analysis

木下 哲一*; 能任 琢真*; 中島 均*; 小迫 和明*; 加藤 雄大*; 黒岩 洋一*; 倉部 美彩子*; 佐々木 勇気*; 鳥居 和敬*; 前田 亮; et al.

Journal of Radioanalytical and Nuclear Chemistry, 332(2), p.479 - 486, 2023/02

https://doi.org/10.1007/s10967-023-08776-w

There are some different chemical and physical forms of water molecules in concretes. Especially, bound water is difficult to determine. In the present work, we determined free + adsorbed water and bound water contained in aggregates and cement pastes, which are component of concretes, by means of conventional gravimetric analysis and prompt -ray analysis (PGA), respectively, in order to evaluate a total water content in concretes. In the PGA, background reduction was attempted by using the time-of-flight (TOF) signal. In addition, the degree of contribution to analytical values by scattered neutrons by samples was evaluated because water would adsorb on the surface of instruments inside the irradiation chamber for the PGA. Contents of the free + adsorbed water and bound water in some geochemical references determined in the present work were compared with the nominal values to confirm the precision. Each water content in aggregates collected from different quarries and cement pastes with different water-to-cement ratios were analyzed. A total water content in young concrete was evaluated on the basis of the analytical values.

Lanthanide and actinide ion complexes containing organic ligands investigated by surface-enhanced infrared absorption spectroscopy

平田 早紀子*; 日下 良二; 明地 省吾*; 為国 誠太*; 奥寺 洸介*; 浜田 昇賢*; 坂本 知優*; 本田 匠*; 松下 高輔*; 村松 悟*; et al.

Inorganic Chemistry, 62(1), p.474 - 486, 2023/01

https://doi.org/10.1021/acs.inorgchem.2c03618

A new technique, surface-enhanced infrared absorption (SEIRA) spectroscopy, was used for the structural investigation of lanthanide (Ln) and actinide (An) complexes containing organic ligands. We synthesized thiol derivatives of organic ligands with coordination sites similar to those of diglycolamide (DGA), Cyanex-272, and -tetrakis(2-pyridinylmethyl)-1,2-ethanediamine (TPEN), which have been used for separating Ln and An through solvent extraction. These ligands were attached on a gold surface deposited on an Si prism through S-Au covalent bonds; the gold surface enhanced the IR absorption intensity of the ligands. Aqueous solutions of Ln (Eu, Gd, Tb) and An (Am) ions were loaded onto the gold surface to form ion complexes. The IR spectra of the ion complexes were obtained using FT-IR spectroscopy in the attenuated total reflection mode. In this study, we developed a new sample preparation method for SEIRA spectroscopy that enabled us to obtain the IR spectra of the complexes with a small amount of ion solution (5 L). This is a significant advantage for the IR measurement of radiotoxic Am complexes. In the IR spectra of DGA, the band attributed to C=O stretching vibrations at 1630 cm shifted to a lower wavenumber by 20 cm upon complexation with Ln and An ions. Moreover, the amount of the red-shift was inversely proportional to the extraction equilibrium constant reported in previous studies on solvent extraction. The coordination ability of DGA toward Ln and An ions could be assessed using the band position of the C=O band. The Cyanex-272- and TPEN-like ligands synthesized in this report also showed noticeable SEIRA signals for Ln and An complexes. This study indicates that SEIRA spectroscopy can be used for the structural investigation of ion complexes and provides a microscopic understanding of selective extraction of Ln and An.

Japanese Evaluated Nuclear Data Library version 5; JENDL-5

岩本 修; 岩本 信之; 国枝 賢; 湊 太志; 中山 梓介; 安部 豊*; 椿原 康介*; 奥村 森*; 石塚 知香子*; 吉田 正*; et al.

Journal of Nuclear Science and Technology, 60(1), p.1 - 60, 2023/01

https://doi.org/10.1080/00223131.2022.2141903

The fifth version of Japanese Evaluated Nuclear Data Library, JENDL-5, was developed. JENDL-5 aimed to meet a variety of needs not only from nuclear reactors but also from other applications such as accelerators. Most of the JENDL special purpose files published so far were integrated into JENDL-5 with revisions. JENDL-5 consists of 11 sublibraries: (1) Neutron, (2) Thermal scattering law, (3) Fission product yield, (4) Decay data, (5) Proton, (6) Deuteron, (7) Alpha-particle, (8) Photonuclear, (9) Photo-atomic, (10) Electro-atomic, and (11) Atomic relaxation. The neutron reaction data for a large number of nuclei in JENDL-4.0 were updated ranging from light to heavy ones, including major and minor actinides which affect nuclear reactor calculations. In addition, the number of nuclei of neutron reaction data stored in JENDL-5 was largely increased; the neutron data covered not only all of naturally existing nuclei but also their neighbor ones with half-lives longer than 1 day. JENDL-5 included the originally evaluated data of thermal scattering law and fission product yield for the first time. Light charged-particle and photon induced reaction data were also included for the first time as the JENDL general purpose file.

Laser-driven neutron generation realizing single-shot resonance spectroscopy

余語 覚文*; Lan, Z.*; 有川 安信*; 安部 勇輝*; Mirfayzi, S. R.*; Wei, T.*; 森 隆人*; Golovin, D.*; 早川 岳人*; 岩田 夏弥*; et al.

Physical Review X, 13(1), p.011011_1 - 011011_12, 2023/01

https://doi.org/10.1103/PhysRevX.13.011011

Neutrons are powerful tools for investigating the structure and properties of materials used in science and technology. Recently, laser-driven neutron sources (LDNS) have attracted the attention of different communities, from science to industry, in a variety of applications, including radiography, spectroscopy, security, and medicine. However, the laser-driven ion acceleration mechanism for neutron generation and for establishing the scaling law on the neutron yield is essential to improve the feasibility of LDNS. In this paper, we report the mechanism that accelerates ions with spectra suitable for neutron generation. We show that the neutron yield increases with the fourth power of the laser intensity, resulting in the neutron generation of in at a maximum, with Wcm, 900 J, 1.5 ps lasers. By installing a "hand-size" moderator, which is specially designed for the LDNS, it is demonstrated that the efficient generation of epithermal (0.1-100 eV) neutrons enables the single-shot analysis of composite materials by neutron resonance transmission analysis (NRTA). We achieve the energy resolution of 2.3% for 5.19-eV neutrons 1.8 m downstream of the LDNS. This leads to the analysis of elements and isotopes within sub-s times and allows for high-speed nondestructive inspection.