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山下 拓哉; 佐藤 一憲; 本多 剛*; 野崎 謙一朗*; 鈴木 博之*; Pellegrini, M.*; 酒井 健*; 溝上 伸也*
Nuclear Technology, 206(10), p.1517 - 1537, 2020/10
被引用回数：0 パーセンタイル：100(Nuclear Science & Technology)The estimation and understanding of the state of fuel debris and fission products inside the plant is an essential step in the decommissioning of the TEPCO Fukushima Daiichi Nuclear Power Station (1F). However, the direct observation of the plant interior, which is under a high radiation environment. Therefore, in order to understand the plant interior conditions, the comprehensive analysis and evaluation is necessary, based on various measurement data from the plant, analysis of plant data during the accident progression phase and information obtained from computer simulations for this phase. These evaluations can be used to estimate the conditions of the interior of the reactor pressure vessel (RPV) and the primary containment vessel (PCV). Herein, 1F Unit 2 was addressed as the subject to produce an estimated map of the fuel debris distribution from data obtained about the RPV and PCV based on the comprehensive evaluation of various measurement data and information obtained from the accident progression analysis, which were released to the public in June 2018.
佐藤 博之; 青木 健; 大橋 弘史
Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 10 Pages, 2020/08
本報告では、HTTR建設を通じて得られた知見に基づき作成した、実用高温ガス炉の燃料設計限度の考え方を提示する。燃料設計限度は、評価指標とこれに対応する判断基準で構成される。はじめに、日本原子力学会研究専門委員会で作成された、実用高温ガス炉の安全要件とこれを満足する設計要求事項に適合する評価指標を選定した。次に、規制要求事項に加えて、放射性物質の閉じ込めに係る物理障壁の性能や放射性物質の閉じ込めを保証する計測制御系の性能を考慮した判断基準策定の手順を決定した。検討の結果、安全上の要求事項を網羅しつつ、合理的な燃料破損率を考慮可能な燃料設計限度の考え方が提示された。
青木 健; 佐藤 博之; 大橋 弘史
Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 6 Pages, 2020/08
ブロック型高温ガス炉の熱流動設計の一部であり、黒鉛ブロック間の漏れ流れを考慮する炉内流量配分評価は、保守的な条件における定常状態に対して実施されていた。一方で、現実的な条件における過渡評価によりブロック型高温ガス炉の設計改善が期待される。本研究では高温工学試験研究炉(HTTR)の知見を活用し、運転時の異常な過渡変化や事故時のブロック型高温ガス炉の過渡流量配分評価のための手法開発とその適用性を確認することが目的である。炉内の漏れ流れと空気侵入事故時の初期空気侵入挙動で支配的な分子拡散を考慮可能な計算モデルと解析コードを開発し検証したことで、改良した熱流動システム解析コードがブロック型高温ガス炉の過渡流量配分評価に適用できる見通しを得た。
青木 健; 井坂 和義; 佐藤 博之; 大橋 弘史
Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 7 Pages, 2020/08
高温ガス炉の設計において実施される流量配分評価では熱や照射による黒鉛構造物の変形と漏れ流れを形成する黒鉛構造物間の隙間の相互作用を考慮する必要がある。本研究では、高温工学試験研究炉の知見を活かし、他の高温ガス炉設計用解析コードとの親和性が高く、手動操作なしで収束計算の中で黒鉛構造物の変形を考慮するユーザーフレンドリーな流路網計算コードを開発するとともに、その解析結果が実験結果とよく一致することを確認した。その結果、ブロック型高温ガス炉における漏れ流れ流路を含めた流路網モデルにおける流量及び圧力分布の解析に対するFNCCが検証された。
at forward and backward rapidity in 
+, 
l, u, and 
He+Au collisions at 
= 200 GeVAcharya, U.*; 長谷川 勝一; 今井 憲一*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他358名*
Physical Review C, 102(1), p.014902_1 - 014902_23, 2020/07
被引用回数：0 パーセンタイル：100(Physics, Nuclear)Charmonium is a valuable probe in heavy-ion collisions to study the properties of the quark gluon plasma, and is also an interesting probe in small collision systems to study cold nuclear matter effects, which are also present in large collision systems. With the recent observations of collective behavior of produced particles in small system collisions, measurements of the modification of harmonium in small systems have become increasingly relevant. We present the results of measurements at forward and backward rapidity in various small collision systems, 
, Al, Au and HeAu, at =200 GeV. The results are presented in the form of the observable 
, the nuclear modification factor, a measure of the ratio of the invariant yield compared to the scaled yield in collisions. We examine the rapidity, transverse momentum, and collision centrality dependence of nuclear effects on production with different projectile sizes and He, and different target sizes Al and Au. The modification is found to be strongly dependent on the target size, but to be very similar for Au and 
HeAu. However, for 0% - 20% central collisions at backward rapidity, the modification for HeAu is found to be smaller than that for Au, with a mean fit to the ratio of 
(stat)
(syst), possibly indicating final state effects due to the larger projectile size.
佐藤 博之; 大橋 弘史
Mechanical Engineering Journal (Internet), 7(3), p.19-00332_1 - 19-00332_11, 2020/06
高温ガス炉コジェネレーションプラントの水素製造施設における有毒ガス漏えい事故に対する確率論的リスク評価手法開発を目的として、コジェネレーション高温ガス炉における有毒ガス漏えい事故時における制御室居住性評価に係る不確かさ評価手法を構築した。また、本開発手法を、HTTRに接続した熱化学法ISプロセスによる水素製造施設に適用した。検討の結果、開発手法により、不確かさの特性把握や定量化が可能であることを明らかにした。また、表面粗度に係る不確かさが制御室の有毒ガス濃度のばらつきに与える影響が大きいことを明らかにした。
柴田 大受; 佐藤 博之; 植田 祥平; 竹上 弘彰; 高田 昌二; 國富 一彦
2018 GIF Symposium Proceedings (Internet), p.99 - 106, 2020/05
第四世代原子力システムの一つである超高温ガス炉(VHTR)システムについて、原子力研究開発機構で実施している研究開発活動の進捗についてまとめた。高温工学試験研究炉(HTTR)は2010年に原子炉出口温度950
Cでの50日間連続運転を達成し、その際、被覆粒子燃料の優れた品質を示した。また、高燃焼度化に向けてZrC被覆粒子の開発を進めている。炉内の構造物に用いる黒鉛の耐酸化性の向上のため、黒鉛へのSiC被覆について中性子照射の影響を調べている。将来の商用高温ガス炉コジェネレーションシステムについて、国際的な安全基準の整備を進めている。HTTRは新規制基準の適合性審査を経て、2019年に再稼働を見込んでいる。ISプロセス連続水素製造試験設備では、2016年に31時間の連続試験が完了した。HTTRでの水素製造-ガスタービン試験に向けた基本設計を完了した。
佐藤 博之; 青木 健; 大橋 弘史; Yan, X. L.
Nuclear Engineering and Design, 360, p.110493_1 - 110493_8, 2020/04
被引用回数：0 パーセンタイル：100(Nuclear Science & Technology)原子力機構は原子力エネルギーの多様な産業利用に向け、HTTR建設の許認可での経験及び知見を活用し、高温ガス炉固有の特徴を反映した、実用高温ガス炉の安全基準国際標化に向けた活動を実施している。本論文では、高温ガス炉コジェネレーションシステムの許認可に向けた研究開発ロードマップを示した。また、安全要件や設計基準事象選定方針等の検討結果や安全評価手法の確立に向けたHTTR試験計画を示した。加えて、実用高温ガス炉における炉心冷却機能を担う安全設備である自然空冷方式による炉容器冷却設備が安全要件国際標準案に適合することを確認した。
大森 惇志*; 秋山 英二*; 阿部 博志*; 端 邦樹; 佐藤 智徳; 加治 芳行; 井上 博之*; 田口 光正*; 清藤 一*; 多田 英司*; et al.
材料と環境, 69(4), p.107 - 111, 2020/04
ガンマ線照射による水のラジオリシスで生成する酸化剤が炭素鋼の気相中の腐食に及ぼす効果を評価するために、オゾンをモデル酸化剤として用いて50Cの湿度制御下に導入し、ACMセンサを用いた腐食モニタリングを行った。ACM電流はオゾンの濃度に伴って高くなったことから、オゾンによる腐食促進の効果が示された。これはオゾンの還元反応あるいは水への溶解反応が早く、カソード反応を促進したためと考えられる。
Al and Au collisions at 
GeVAidala, C.*; 長谷川 勝一; 今井 憲一*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他297名*
Physical Review C, 101(3), p.034910_1 - 034910_16, 2020/03
被引用回数：2 パーセンタイル：13.44(Physics, Nuclear)The PHENIX experiment has studied nuclear effects in Al and Au collisions at GeV on charged hadron production at forward rapidity (
, -going direction) and backward rapidity (
, 
-going direction). Such effects are quantified by measuring nuclear modification factors as a function of transverse momentum and pseudorapidity in various collision multiplicity selections. In central Al and Au collisions, a suppression (enhancement) is observed at forward (backward) rapidity compared to the binary scaled yields in + collisions. The magnitude of enhancement at backward rapidity is larger in Au collisions than in Al collisions, which have a smaller number of participating nucleons. However, the results at forward rapidity show a similar suppression within uncertainties. The results in the integrated centrality are compared with calculations using nuclear parton distribution functions, which show a reasonable agreement at the forward rapidity but fail to describe the backward rapidity enhancement.
and 
production at forward rapidity in + collisions at 
GeVAcharya, U. A.*; 長谷川 勝一; 今井 憲一*; 永宮 正治*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他353名*
Physical Review D, 101(5), p.052006_1 - 052006_13, 2020/03
被引用回数：0 パーセンタイル：100(Astronomy & Astrophysics)The PHENIX experiment at the Relativistic Heavy Ion Collider has measured the differential cross section, mean transverse momentum, mean transverse momentum squared of inclusive and cross-section ratio of to at forward rapidity in 
collisions at 
GeV via the dimuon decay channel. Comparison is made to inclusive cross sections measured at 
GeV and 2.76 - 13 TeV. The result is also compared to leading-order nonrelativistic QCD calculations coupled to a color-glass-condensate description of the low-
gluons in the proton at low transverse momentum (
) and to next-to-leading order nonrelativistic QCD calculations for the rest of the range. These calculations overestimate the data at low . While consistent with the data within uncertainties above 
GeV/
, the calculations are systematically below the data. The total cross section times the branching ratio is BR 
GeV/) = 54.3 
0.5 (stat) 5.5 (syst) nb.
Jung, W.*; Ahn, J. K.*; 長谷川 勝一; Hicks, K.*; Hwang, S.*; 市川 裕大; Kim, S.*; 佐甲 博之; 佐藤 進; 谷田 聖
JPS Conference Proceedings (Internet), 27, p.011007_1 - 011007_6, 2019/11
We have developed HypTPC consists of TPC and the trigger hodoscope for the J-PARC hadron experiments. The TPC Hodoscope has large scintillators of 80 
7 1 cm to cover the TPC. Especially, we have developed a readout circuit for multiple MPPCs to detect photons generated over a large area of the scintillator. A general methods of applying voltage to multiple MPPCs are parallel and series connections. In the case of parallel connections, a signal has a long tail due to the large sensor capacitance. MEG collaboration used four MPPC segments as a serial connection. However, in the case of a series connection, the requiring bias voltage is very high, and the gain is low. To avoid this problem, we have developed a new individual biasing method with a summing amplifier for stable multiple MPPC readouts. We also made prototype detectors and performed a cosmic-ray test. Brief descriptions of our prototypes and preliminary results of the cosmic-ray test are presented in this article.
scattering experiment at J-PARC and the analysis status中田 祥之*; 長谷川 勝一; 早川 修平*; 細見 健二; 市川 裕大; 今井 憲一; 七村 拓野*; 成木 恵*; 佐甲 博之; 佐藤 進; et al.
JPS Conference Proceedings (Internet), 26, p.023024_1 - 023024_5, 2019/11
J-PARC E40 aims to measure the differential cross sections of the 
elastic scatterings and the 
conversion. A clear peak of 
was observed in a missing mass spectrum of the 
reaction and recoil protons from the 
elastic scattering were successfully observed in the data taken in the summer 2018. The rest of data taking is coming in the spring 2019.
-ray spectroscopy of an 
-shell hypernucleus, 
FYang, S. B.*; 長谷川 勝一; 早川 修平*; 細見 健二; 市川 裕大; 今井 憲一; 佐甲 博之; 佐藤 進; 田村 裕和*; 谷田 聖; et al.
JPS Conference Proceedings (Internet), 26, p.023015_1 - 023015_5, 2019/11
We performed a gamma-ray spectroscopy of 
at J-PARC Hadron Experimental Facility in 2015. It is the first measurement of rays emitted from -shell hypernuclei. In this experiment, we determined the energy spacing between the ground state spin doublet, 
and 
states, as 316 keV. The excitation energies of 
and states are also determined to be 895 and 1266 keV, respectively. The energy spacing is found to be well reproduced by shell-model calculations which describe 
- and -shell 
hypernuclei well. The results show that the present theories of the 
interaction describe not only the light hypernuclei but also a heavier hypernucleus.
in nuclei through C
spectrum at 1.8 GeV/ in the J-PARC E05 experiment本多 良太郎*; 長谷川 勝一; 早川 修平; 細見 健二; 今井 憲一; 市川 裕大; 七村 拓野; 成木 恵; 佐甲 博之; 佐藤 進; et al.
JPS Conference Proceedings (Internet), 26, p.023014_1 - 023014_4, 2019/11
We measured the 
reaction spectra at 1.8 GeV/ for the graphite and the polyethylene targets in the J-PARC E05 pilot experiment. By comparing the spectra for these two targets, it was found that 
in the 
B nucleus is quite broadened. Furthermore, we also compared broadness of with 
obtained in the 
spectrum. seems to be much more broadened in nuclei than . We gave a possible interpretation, which is related to compositeness of decuplet baryons, for this situation.
hypernucleus in the J-PARC E13 experiment中川 真菜美*; 長谷川 勝一; 早川 修平; 細見 健二; 市川 裕大; 今井 憲一; 佐甲 博之; 佐藤 進; 田村 裕和; 谷田 聖; et al.
JPS Conference Proceedings (Internet), 26, p.023005_1 - 023005_3, 2019/11
The 
interaction is not much studied than the interaction. To understand the interaction, we study 
hypernuclei. As for the hypernucleus, only the ground state of has been observed. To obtain more information about the interaction, the excited state should be studied. Therefore, we measure the missing-mass of the 
He
reaction at 
GeV/ and 
2-14 at the J-PARC K1.8 beam line. The ground state of is observed whereas a peak of the excited states is not observed. We also observe suppression of the quasi-free process at smaller angles.
Kim, S. H.*; 市川 裕大; 佐甲 博之; 長谷川 勝一; 早川 修平*; 七村 拓野*; 佐藤 進; 谷田 聖; 吉田 純也; 他11名*
Nuclear Instruments and Methods in Physics Research A, 940, p.359 - 370, 2019/10
被引用回数：2 パーセンタイル：34.3(Instruments & Instrumentation)We have developed a gas electron multiplier (GEM)-based time projection chamber (TPC) for the H-dibaryon search experiment at J-PARC. High-rate 
beam particles enter a TPC gas volume of approximately 0.2 m, in a direction perpendicular to the electric field. A long-rectangular hollow section is located inside the TPC volume to accommodate a diamond target. We commissioned the TPC using 230 MeV protons with beam rates of up to 1 MHz. The TPC data acquisition system collected 5768 pad signals in full readout mode, with almost 100% efficiency, at a preset trigger rate of 230 Hz. We operated the TPC in an Ar/CH
gas mixture (90/10) without a magnetic field. The spatial resolutions on the pad plane are measured to be 400-700 
m, which correspond to 230-300 m in a magnetic field of 1 T. We confirmed high tracking capability at beam rates of up to 1 MHz.
, Al, and Au collisions at GeVAidala, C.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他296名*
Physical Review Letters, 123(12), p.122001_1 - 122001_9, 2019/09
被引用回数：2 パーセンタイル：45.7(Physics, Multidisciplinary)We report on the nuclear dependence of transverse single-spin asymmetries (TSSAs) in the production of positively-charged hadrons in polarized 
, 
Al and Au collisions at GeV. The measurements have been performed at forward rapidity (
) over the range of 
GeV
and 
. We observed a positive asymmetry 
for positively-charged hadrons in collisions, and a significantly reduced asymmetry in 
+ collisions. These results reveal a nuclear dependence of charged hadron 
in a regime where perturbative techniques are relevant. These results provide new opportunities to use A collisions as a tool to investigate the rich phenomena behind TSSAs in hadronic collisions and to use TSSA as a new handle in studying small-system collisions.
-hypernuclei at J-PARC; Results and perspective小池 武志*; 長谷川 勝一; 早川 修平*; 細見 健二; 市川 裕大; 今井 憲一; 佐甲 博之; 佐藤 進; 杉村 仁志; 田村 裕和; et al.
AIP Conference Proceedings 2130, p.020011_1 - 020011_9, 2019/07
被引用回数：0 パーセンタイル：100Experimental results from the J-PARC E13 experiments are summarized. A new experimental set up of E13 has established a platform for the future -ray hypernuclear spectroscopy at J-PARC using kaon beams. New rays are identified in 
He and F. The energy of 1.406 MeV for the He
transition confirmed a sizable effect of Charge Symmetry Breaking (CSB) in interaction in the 
hypernuclear system. The identification of four rays in F is made for the first time in shell hypernuclei. Especially, energy spacing of the ground state doublet is found to be 315.5 keV. A good agreement with two theoretical calculations suggests that the theoretical formalism used in shell hypernuclei is also applicable to heavier hypernuclei. Lastly, an overview of the future J-PARC E63 experiment is given.
bound state in the 
C
reaction at 1.8 GeV/永江 知文*; 江川 弘行; 長谷川 勝一; 早川 修平; 細見 健二; 市川 裕大; 今井 憲一; 金原 慎二; 七村 拓野*; 成木 恵; et al.
AIP Conference Proceedings 2130, p.020015_1 - 020015_9, 2019/07
For the full understanding of baryon-baryon interactions in flavor 
, the 
interaction is the last missing piece of information. So far, we have revealed the interaction to be attractive (
MeV), and interaction to be repulsive in the medium to heavy mass-number region. The 
bonding energy is weakly attractive. While we have a few experimental observations suggesting the interaction would be attractive, there still exist large theoretical ambiguities weather it is attractive or not. Experimental determinations on the existence of bound states of hypernuclei by observing bound-state peaks are strongly awaited. In this report, a new preliminary result on the missing-mass spectrum of a C reaction, which strongly suggests the existence of -hypernuclear bound states, is presented.
