Methodology development for explosion hazard evaluation in hydrogen production system using high temperature gas-cooled reactor

守田 圭介; 青木 健; 清水 厚志; 佐藤 博之

Proceedings of 31st International Conference on Nuclear Engineering (ICONE31) (Internet), 6 Pages, 2024/11

https://doi.org/10.1115/ICONE31-135407

High temperature gas-cooled reactor (HTGR) is expected to use nuclear heat to wide range of industrial applications such as hydrogen production, which is capable of high temperature heat supply with inherent safe characteristics. JAEA started a High Temperature engineering Test Reactor (HTTR) heat application test project to develop coupling technologies between HTGR and a hydrogen production plant necessary to achieve large-scale, carbon-free hydrogen production. One of the key technologies is a safety evaluation method which can simulate an impact of explosion hazards induced in the hydrogen production plant on reactor facility because HTGR hydrogen production system contains large amount of combustible gases such as hydrogen. A computational fluid dynamics code FLACS has been sufficiently validated for dispersion and explosion of combustible gases such as hydrogen and methane worldwide, however, only few attempts have been made for validation of analysis in closed area with small space. A leak of combustible gases to the piping in HTGR hydrogen production system may occur in case of abnormal condition in hydrogen production plant and therefore an explosion in the piping must be considered. This paper describes the validation of FLACS by analyzing explosion experiments in straight piping and complex piping aiming to establish a safety evaluation method for analyzing explosions of combustible gases in piping.

Validation of dynamic analysis code for high temperature gas-cooled reactor connecting hydrogen production system with a heat removal fluctuation mitigation system

長谷川 武史; 青木 健; 清水 厚志; 佐藤 博之

Proceedings of 14th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation, and Safety (NUTHOS-14) (Internet), 12 Pages, 2024/08

日本原子力研究開発機構(JAEA)は、大洗研究所にある高温ガス炉(HTGR)の試験炉である、30MWtのHTTR(高温工学試験研究炉)に水素製造装施設を接続する水素製造実証試験を計画している。この試験の目的は、高温ガス炉と水素製造プラントとの接続技術を確立することである。この試験によって確立される接続技術の1つに、水素製造プラントで熱負荷が失われた際のヘリウム温度の急激な変動を緩和できる、蒸気発生器と放熱器で構成される熱負荷変動緩和システムがある。本研究の目的は、水素製造設備を接続したHTTRの安全解析において熱負荷変動緩和システムの評価モデルが適用可能なことを検証することである。RELAP5ベースの動特性解析コードに一連の循環流路モデルを新たに導入することで、ヘリウムで加熱する蒸気発生器と外気で冷却する放熱器との間の蒸気と水の自然循環を評価できるようにし、熱負荷変動緩和システムのモックアップ試験設備から得られた実験データと評価モデルの数値解析結果を比較した。比較の結果、数値解析結果が実験結果とよく一致することが確認された。結論として、検証した評価モデルは、高温ガス炉を用いた水素製造システムに導入される熱負荷変動緩和システムの安全解析に適用可能である。

高温ガス炉と水素製造施設の接続技術開発; HTTR-熱利用試験計画

石井 克典; 守田 圭介; 野口 弘喜; 青木 健; 水田 直紀; 長谷川 武史; 永塚 健太郎; 野本 恭信; 清水 厚志; 飯垣 和彦; et al.

第27回動力・エネルギー技術シンポジウム講演論文集(インターネット), 4 Pages, 2023/09

https://doi.org/10.1299/jsmepes.2023.27.A242

JAEA initiated the HTTR heat application test project coupling a hydrogen production facility to the HTTR (high temperature engineering test reactor). The project aims to establish "coupling technologies" between HTGR and hydrogen production achieving large-scale, stable and economically competitive carbon-free hydrogen production using the HTGR heat. Important considerations towards establishment of coupling technologies are development of system technologies for HTGR hydrogen production systems and components required for coupling between two facilities. This paper explains a system concept of the HTTR heat application system which can maintain safe and stable operation of the HTTR against temperature transients induced by abnormal events in a hydrogen production plant with the results of operational scheme as well as heat and mass balance of the system. Development plans for hot gas duct, high temperature isolation valves and helium gas circulators are also presented.

Development plan for coupling technology between high temperature gas-cooled reactor HTTR and Hydrogen Production Facility, 2; Development plan for coupling equipment between HTTR and Hydrogen Production Facility

水田 直紀; 守田 圭介; 青木 健; 沖田 将一朗; 石井 克典; 倉林 薫; 安田 貴則; 田中 真人; 井坂 和義; 野口 弘喜; et al.

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 6 Pages, 2023/05

High temperature gas-cooled reactor (HTGR) is expected to extend the use of nuclear heat to a wider spectrum of industrial applications such as hydrogen production, high efficiency power generation, etc., due largely to high temperature heat supply capability as well as inherent safe characteristics. Japan Atomic Energy Agency (JAEA) have been contracted by the Agency for Natural Resources and Energy, part of the Ministry of Economy, Trade and Industry (METI) of Japan, to conduct its Hydrogen Production Demonstration Project Utilizing Very High Temperature. The primary objective of this project is to establish "coupling technology" between HTGR and hydrogen production facility in accordance with "Green Growth Strategy Through Achieving Carbon Neutrality in 2050". From this fiscal year, JAEA initiated a program to produce hydrogen using an HTTR (High Temperature Engineering Test Reactor) to develop coupling technologies between HTGR and hydrogen production facility required for a massive, cost-effective and carbon-free hydrogen production technology. This paper describes the development plan for coupling equipment which is required for an HTTR heat application test as coupling technologies between an HTTR and a hydrogen production facility. The coupling equipment is composed of a high temperature isolation valve to prevent the ingress of the flammable gas and/or the leakage of radioactive materials for nuclear facility, a secondary helium gas circulator to feed a high temperature helium gas, and a high temperature insulation pipe to transport of a high temperature helium gas from an Internal Heat Exchanger (IHX) to a hydrogen production facility. The development plan of coupling equipment contains each target and draft schedule.

Validation of evaluation model for analysis of steam reformer in HTGR hydrogen production plant

石井 克典; 青木 健; 井坂 和義; 野口 弘喜; 清水 厚志; 佐藤 博之

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 9 Pages, 2023/05

https://doi.org/10.1299/jsmeicone.2023.30.1074

JAEA initiated High Temperature engineering Test Reactor (HTTR) heat application test project to establish coupling technologies between HTGR and a hydrogen production plant necessary to achieve large-scale, low cost, and carbon-free hydrogen production. One important element for the coupling technologies is a system analysis code which can simulate dynamic behavior of a HTGR hydrogen production system to design a plant control system for the effects of circulated helium heat through both facilities. The code is required to deal with a complex system which involves several subsystems and different physics with different timescales. As a first step of the development, we developed a heat and mass balance evaluation model of a helium-heated steam reformer. This report will present the outline of the developed model and simulation results with comparison to the experimental results.

HTTR-熱利用試験専門委員会資料集

青木 健; 清水 厚志; 飯垣 和彦; 沖田 将一朗; 長谷川 武史; 水田 直紀; 佐藤 博之; 坂場 成昭

JAEA-Review 2022-016, 193 Pages, 2022/08

JAEA-Review-2022-016.pdf:42.06MB

日本原子力研究開発機構では、高温ガス炉による大量かつ安価なカーボンフリー水素製造技術の実用化を目指し、世界最高の原子炉出口冷却材温度950Cを記録した高温工学試験研究炉(HTTR)を用いて水素製造を行うHTTR-熱利用試験を計画している。HTTR-熱利用試験では、原子力規制委員会からの設置許可取得を通じて、高温ガス炉と水素製造施設の接続に関し、高い安全性を実現する安全設計を確立することが求められている。しかしながら、これまでに原子炉に水素製造施設を接続した例は世界にまだなく、我が国唯一の高温ガス炉であるHTTRを含め、既存の原子力施設を対象とした安全設計ではこのようなシステムを想定していない。そこで、高温ガス炉研究開発センターの下に設置した「HTTR-熱利用試験専門委員会」では、原子力規制委員会による新規制基準への適合性審査に合格したHTTR安全設計をベースに、施設の変更や水素製造施設の接続に伴い安全設計上新たに考慮すべき事象に対する対策を考慮し、HTTR-熱利用試験施設の安全設計案の検討を行った。本稿は、HTTR-熱利用試験専門委員会の技術報告資料や委員コメントとその回答、議事録を取りまとめた。

PSTEP: Project for solar-terrestrial environment prediction

草野 完也*; 一本 潔*; 石井 守*; 三好 由純*; 余田 成男*; 秋吉 英治*; 浅井 歩*; 海老原 祐輔*; 藤原 均*; 後藤 忠徳*; et al.

Earth, Planets and Space (Internet), 73(1), p.159_1 - 159_29, 2021/12

https://doi.org/10.1186/s40623-021-01486-1

PSTEPとは、2015年4月から2020年3月まで日本国内の太陽・地球惑星圏に携わる研究者が協力して実施した科研費新学術領域研究である。この研究枠組みから500以上の査読付き論文が発表され、様々なセミナーやサマースクールが実施された。本論文では、その成果をまとめて報告する。

Porous metal-organic frameworks containing reversible disulfide linkages as cathode materials for lithium-ion batteries

清水 剛志*; Wang, H.*; 松村 大樹; 光原 圭*; 太田 俊明*; 吉川 浩史*

ChemSusChem, 13(9), p.2256 - 2263, 2020/05

https://doi.org/10.1002/cssc.201903471

Three porous disulfide-ligand-containing metal-organic frameworks (DS-MOFs) and two nonporous coordination polymers with disulfide ligands (DS-CPs) with various structural dimensionalities were used as cathode active materials in lithium batteries. Charge/discharge performance examinations revealed that only porous DS-MOF-based batteries exhibited significant capacities close to the theoretical values, which was ascribed to the insertion of electrolyte ions into the DS-MOFs. Battery reactions were probed by instrumental analyses. The dual redox reactions of metal ions and disulfide ligands in the MOFs resulted in higher capacities, and the presence of reversible electrochemically dynamic S-S bonds stabilized the cycling performance. Thus, the strategy of S-S moiety trapping in MOFs and the obtained correlation between the structural features and battery performance could contribute to the design of high-performance MOF-based batteries and the practical realization of Li-S batteries.

Rechargeable batteries based on stable redox reactions of disulfide included in a metal-organic framework as ligands

清水 剛志*; Wang, H.*; 谷藤 尚貴*; 松村 大樹; 吉村 真史*; 中西 康次*; 太田 俊明*; 吉川 浩史*

Chemistry Letters, 47(5), p.678 - 681, 2018/05

https://doi.org/10.1246/cl.180121

Disulfide, which is a sub-group of organosulfides, has been studied as a promising cathode active material. Herein, to improve battery performance, we inserted disulfide into Cu-based metal organic framework (MOF) as a ligand. As a result, the disulfide inserted MOF exhibited a high capacity based on dual redox reactions of Cu ions and disulfide ligands, and a stable cycle performance. The S -edge X-ray absorption fine structure analyses revealed a reversible cleavage and formation of S-S bond in the MOF during discharge and charge process.

Predoping effects of boron and phosphorous on arsenic diffusion along grain boundaries in polycrystalline silicon investigated by atom probe tomography

高見澤 悠; 清水 康雄*; 井上 耕治*; 野沢 康子*; 外山 健*; 矢野 史子*; 井上 真雄*; 西田 彰男*; 永井 康介*

Applied Physics Express, 9(10), p.106601_1 - 106601_4, 2016/10

https://doi.org/10.7567/APEX.9.106601

The effect of phosphorus (P) and boron (B) doping on arsenic (As) diffusion in polycrystalline silicon (poly-Si) was investigated using laser-assisted atom probe tomography. In all samples, a high concentration of As was found at the grain boundaries, indicating that such boundaries represent the main diffusion path. However, As grain-boundary diffusion was suppressed in the B-doped sample, and enhanced in the P-doped sample. In a sample co-doped with both P and B, As diffusion was somewhat enhanced, indicating competition between the effects of the two dopants. This can be explained by the pairing of P and B atoms. The results suggest that grain-boundary diffusion of As can be controlled by varying the local concentration of P and B dopants.