Neutron transmission measurements for silica glass at the KURNS-LINAC

Lee, J.; Rossi, F.; 児玉 有; 弘中 浩太; 小泉 光生; 佐野 忠史*; 松尾 泰典*; 堀 順一*

Annals of Nuclear Energy, 211, p.111017_1 - 111017_7, 2025/02

https://doi.org/10.1016/j.anucene.2024.111017

Silica glass has been used as a base and host material in vitrified radioactive waste and lithium glass scintillator for neutron detection because of its superb transparency, high heat resistance, and excellent chemical inertness. Therefore, an accurate total cross section of the silica glass is important to evaluate the criticality safety for the vitrified wastes and to understand the neutron response for lithium glass scintillators accurately. In the present study, to provide the accurate total cross section in the thermal and epithermal energy range, the neutron transmission measurements were carried out by a pulsed neutron beam with the time-of-flight method at the Kyoto University Institute for Integrated Radiation and Nuclear Science - Linear Accelerator. We obtained the neutron total cross section of the silica glass in the energy region from 0.002 eV to 25 eV. The obtained results were compared and discussed with the previous results and the evaluated data.

Development of a forward Monte Carlo based weight-window generator using the history-counter function in PHITS

佐藤 達彦; 橋本 慎太郎; Mrquez Damin, J. I.*; 仁井田 浩二*

Nuclear Instruments and Methods in Physics Research B, 557, p.165535_1 - 165535_8, 2024/12

https://doi.org/10.1016/j.nimb.2024.165535

Appropriate use of the variance reduction techniques such as weight-windows are indispensable for effectively designing the radiation shielding based on the Monte Carlo simulation. In this study, we developed a new algorithm of weight-window generator (WWG) relying solely on forward Monte Carlo simulation and implemented it into the Particle and Heavy Ion Transport code System (PHITS). Our new algorithm leverages a PHITS-specific function called the "history counter", which serves as an event logger that can be arbitrarily defined by users. The performance of the new WWG was investigated by conducting benchmark simulations for both idealized and practical shielding calculations. The results of the benchmark simulations suggested that our new algorithm can reduce the computational time by up to an order of magnitude, though it becomes less beneficial when no apparent pathway for particles arriving in the tally regions is observed in generating the weight window values. With this new feature, PHITS has become further suitable for the shielding calculations against high-energy radiations even when their evaluated cross-section data are unavailable.

Initial verification and validation of a new CASMO5 JENDL-5 nuclear data library for typical LWR applications

渡邉 友章; 須山 賢也; 多田 健一; Ferrer, R. M.*; Hykes, J.*; Wemple, C. A.*

Nuclear Science and Engineering, 198(11), p.2230 - 2239, 2024/11

https://doi.org/10.1080/00295639.2023.2295075

先進的格子計算コードCASMO5用の新しい核データライブラリをJENDL-5に基づいて作成した。JENDL-5では、従来の軽水炉解析に不可欠な多くの核種の核データが最新の評価に基づいて更新されている。新しいJENDL-5ベースのCASMO5ライブラリは、現行のCASMO5用ENDF/B-VII.1ベースのライブラリの核データを可能な限りJENDL-5に置き換えることにより作成された。本研究では、この新しいライブラリの検証と妥当性の確認を行った。OECD/NEA燃焼度クレジット臨界安全ベンチマークフェーズIII-Cに基づき検証を行い、計算されたk及びBWR燃料集合体の燃料組成を報告されているベンチマーク結果と比較した。また、同じベンチマークモデルを用いてMCNP6.2の結果との比較も行った。さらに、TCA臨界実験と高浜3号照射後試験を検証に用いた。その結果、新しいライブラリは、軽水炉システムの反応度及び燃料組成の予測において、ENDF/B-VII.1ベースのライブラリと同等かつ良好な性能を示した。

neutron diffraction study to elucidate hydrogen effect on the deformation mechanism in Type 310S austenitic stainless steel

伊東 達矢; 小川 祐平*; Gong, W.; Mao, W.*; 川崎 卓郎; 岡田 和歩*; 柴田 曉伸*; Harjo, S.

Proceedings of the 7th International Symposium on Steel Science (ISSS 2024), p.237 - 240, 2024/11

https://doi.org/10.2355/isijisss.2024.0_237

Hydrogen embrittlement has long been an obstacle to the development of safe infrastructure. However, in contrast to hydrogen's embrittling effect, recent research has revealed that the addition of hydrogen improves both the strength and uniform elongation of AISI Type 310S austenitic stainless steel. A detailed understanding of how hydrogen affects the deformation mechanism of this steel could pave the way for the development of more advanced materials with superior properties. In the present study, neutron diffraction experiments were conducted on Type 310S steel with and without hydrogen-charged to investigate the effect of hydrogen on the deformation mechanism. In addition to the effect of solid-solution strengthening by hydrogen, the q-value, a parameter representing the proportion of edge and screw dislocations in the accumulated dislocations, was quantitatively evaluated using CMWP analysis on neutron diffraction patterns. The comparison of q-values between the hydrogen-charged and non-charged samples reveals that hydrogen has minimal effect on dislocation character in Type 310S steel.

Heat transfer coefficients model for SIMMER-III and SIMMER-IV

Brear, D. J.*; 近藤 悟; 曽我部 丞司; 飛田 吉春*; 神山 健司

JAEA-Research 2024-009, 134 Pages, 2024/10

JAEA-Research-2024-009.pdf:2.45MB

SIMMER-III/SIMMER-IVは液体金属高速炉の炉心崩壊事故(CDA)の解析に使用する計算コードである。CDAの事象進展は炉心物質間の熱伝達係数(HTC)により大きく影響される。溶融・固化、蒸発・凝縮といった質量移行現象も熱伝達により支配される。複雑な多相・多成分系においては、一つの流体成分と他の流体又は構造材表面との間での多数の異なるHTCを計算する必要がある。また、多相流の流動様式や構造材の配位に従って異なる伝熱モードを考慮する必要もある。結果として、各計算セルごとに数十のHTCが計算される。本報告書には、SIMMER-III/SIMMER-IVのHTCモデルの役割、選定したHTC相関式とその技術的背景、流動様式の取扱いとHTCの内挿方法、検証及び妥当性確認の成果概要を記載する。

The Impact of climate on relief in the northern Japanese Alps within the past 1 Myr; The case of the Tateyama mountains

Bartz, M.*; King, G. E.*; Bernard, M.*; Herman, F.*; Wen, X.*; 末岡 茂; 塚本 すみ子*; Braun, J.*; 田上 高広*

Earth and Planetary Science Letters, 644, p.118830_1 - 118830_11, 2024/10

https://doi.org/10.1016/j.epsl.2024.118830

The impact of climate on mountain relief is unknown, mainly due to the difficulties of measuring surface processes at the timescale of glacial-interglacial cycles. An appropriate setting for studying mountain erosion in response to Quaternary climate change is found in the Tateyama mountains in the Hida mountain range (northern Japanese Alps) due to distinct geomorphological features of glacial, periglacial, and fluvial processes. The Japanese Alps uplifted within the past ca 1-3 Myr and experienced multiple glaciations during the late Quaternary. We use ultra-low temperature thermochronometers based on the luminescence of feldspar minerals and the electron spin resonance (ESR) of quartz minerals, in combination with inverse modelling to derive rock cooling rates and exhumation rate histories at 10-10 year timescales from 19 rock samples from three transects in the Tateyama region. While luminescence signals have already reached their upper dating limit, ESR signals (Al and Ti centres) yielded ESR ages of ca 0.3-1.1 Ma, implying surface processes active in the Pleistocene. Based on a negative age-elevation relationship, local relief reduction at a cirque-basin scale is identified over the past 1 Myr, whereas a positive age distribution with elevation for samples close to the mountain top does not follow this trend. Inverse modelling reveals rock cooling rates on the order of 30-80 deg. C/Ma, with slightly faster cooling for cirque-floor samples, which equate with erosion rates of 0.5-1 mm/yr that exceed rates from periglacial and fluvial processes in the same locality. Thus, our data suggest that Quaternary climate change coupled with distinct surface processes modified the slopes of the Tateyama mountains leading to a localised decrease in relief over the second half of the Quaternary, whilst the mountain peaks were unaffected by the relief reduction.

LET-based approximation of the microdosimetric kinetic model for proton radiotherapy

Parisi, A.*; Furutani, K. M.*; 佐藤 達彦; Beltran, C. J.*

Medical Physics, 51(10), p.7589 - 7605, 2024/10

https://doi.org/10.1002/mp.17337

本研究では、陽子線治療における生物学的相対有効性(RBE)モデルの課題に対処するため、LET(線量平均線エネルギー伝達)に基づく近似的なMKM(マイクロドシメトリックキネティックモデル)を開発した。これは、炭素イオン治療で使用されるメカニズムに基づくアプローチを陽子線に適用する試みでる。このLETベースのMKMは、線量平均LETと微生物学的指標の相関を確立し、複数の細胞株に対する生存率のモデリングに成功した。これにより、陽子線治療計画システムで容易に利用可能な物理量に基づくRBEの数学的記述が実現された。

The LINACs simulation framework

Yee-Rendon, B.; Jameson, R. A.*; 岡村 昌宏*; Li, C.*; Jiang, P.*; Maus, J. M.*

Proceedings of 32nd Linear Accelerator Conference (LINAC 2024) (Internet), p.492 - 495, 2024/10

https://doi.org/10.18429/JACoW-LINAC2024-TUPB077

LINACsは、粒子加速器内の荷電粒子の光学系とビーム ダイナミクスを設計するためのシミュレーションのフレームワークであり、RFQのすべての設計パラメータとシミュレーションパラメータをユーザーが完全に制御できるオープンソースのフトウェアである。ビーム駆動設計、正確な四極対称性を使用した完全3Dシミュレーション、外部および空間電荷場に対する厳密なポアソン解を含む。本コードは、解析入力分布を伴う粒子ビームを同時に処理でき、入力ビームの状態がスキャン可能である。本ソフトウェアは実行時間が比較的短くかつ広範な分析情報を提供する。本発表では、コードの歴史的な概要を説明するとともにRFQモデルの結果を提示し、将来の開発について議論する。

France-Japan collaboration on severe accident studies in sodium-cooled fast reactors, 3; Thermodynamic, Kinetic, and Thermophysical Studies of Core Material Mixture

山野 秀将; 江村 優軌; 高井 俊秀; 久保 重信; Quaini, A.*; Fossati, P.*; Delacroix, J.*; Journeau, C.*

Proceedings of International Conference on Nuclear Fuel Cycle (GLOBAL2024) (Internet), 4 Pages, 2024/10

本論文では、炉心混合物質の相互作用に関する反応速度論、二酸化ウラン(UO)と鉄(Fe)と単価ホウ素(BC)に対する高温熱物性データ、BCとステンレス鋼(SS)並びにBC-SS共晶物再配置(固化も)に関する実験研究、シビアアクシデントコードにBC-SS共晶物と反応モデルを組み込む。

Iron coupled with hydroxylamine turns on the "switch" for free radical degradation of organic pollutants under high pH conditions

Tian, Q.*; Feng, L.*; Wu, C.*; Wen, J.*; Qiu, X.*; 田中 万也; 大貫 敏彦*; Yu, Q.*

Journal of Colloid and Interface Science, 669, p.1006 - 1014, 2024/09

https://doi.org/10.1016/j.jcis.2024.05.021

In this study, we assessed the impact of solution pH on organic pollutant degradation by goethite with the addition of hydroxylamine. This study demonstrated that the system can continuously scavenge organic pollutants through oxygen-mediated generation of free radicals under alkaline conditions.