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CPham, V. H.; 倉田 正輝; 永江 勇二; 石橋 良*; 佐々木 政名*
Corrosion Science, 255, p.113098_1 - 113098_9, 2025/10
被引用回数：1 パーセンタイル：0.00(Materials Science, Multidisciplinary)Being expected as materials for accident tolerant fuel cladding tube, oxidation behavior and kinetics of silicon carbide (SiC) under extreme conditions like severe accidents must be elucidated. In this study, oxidation tests of SiC at 1400-1600 C for 1-5 h, at atmospheric pressure, under two different flow rates of H
O/Ar gas mixture have been conducted to investigate the influence of steam flow rate on the formation of SiO scale and its subsequent volatilization. The oxidation tests were conducted via a newly developed test facility using laser as a heat source. Oxidation kinetics of SiC was evaluated via mass change of samples before and after the oxidation tests. Parabolic oxidation rate representative for SiO formation and linear volatilization rate reflecting its volatilization were calculated, based on these mass changes. The Arrhenius dependence of the parabolic oxidation and linear volatilization rate constants were then plotted. Results of this study indicated that SiC exhibits excellent performance under the conditions investigated. Steam flow rate has a significant influence on volatilization of SiO but has minor effects over its formation. Oxidation of SiC in steam at high temperature may follow mass gain or mass loss regime, depending on the steam flow rate. Two oxidation patterns were suggested and discussed. In the first oxidation pattern, the SiO formation is dominated over its volatilization. The second oxidation pattern (steady stage) is reached when the SiO formation rate is equivalent to its volatilization rate. Time to reach this steady stage was defined, based on the parabolic oxidation rate and linear volatilization rate.
河合 慶人*; 根本 義之; 藤村 由希; 近藤 啓悦; 阿部 陽介; Mohamad, A. B.; Pham, V. H.; 石川 法人; 石島 暖大; 井岡 郁夫; et al.
日本原子力学会和文論文誌(インターネット), 24(3), p.82 - 98, 2025/08
現行のジルカロイ被覆管よりも事故耐性に優れた事故耐性燃料(ATF)被覆管の開発が進められている。その一つに外面にCrをコーティングしたコーティング被覆管があり、高温水蒸気中での耐酸化性の向上が見込まれている。しかし、冷却水損失事故(LOCA)時には被覆管が破裂し、コーティングされていない被覆管内面も酸化することが予想される。そこで、本研究ではジルカロイ4被覆管とその外表面にCrコーティングを施したコーティング被覆管を用いてLOCA試験及び高温水蒸気中での酸化試験を行い、酸化挙動、水素吸収挙動及び機械特性の違いを検討した。熱天秤を用いた酸化試験の結果においては、コーティング被覆管は非コーティング被覆管と比較して酸化量が半減し、コーティングの酸化抑制効果が示された。しかし、酸化試験後の試料の水素吸収量を測定したところ、同じ酸化試験条件でも、コーティング被覆管での方が非コーティング被覆管よりも、水素吸収量が多いことがわかった。本報では、この水素吸収量の違いの原因や、それに関連した酸化試験後の機械的性質への影響などについて議論した。
Pshenichnikov, A.; Zubekhina, B.; 多木 寛; Pham, V. H.
Proceedings of International Topical Workshop on Fukushima Decommissioning Research 2024 (FDR2024) (Internet), 4 Pages, 2024/10
The CLADS-MADE-05 is the next test in the series of large-scale tests performed in JAEA with a purpose of understanding of mock-up assembly degradation and melt propagation behaviour accompanied by Cs and B containing aerosol release. A possibility of Cs and B aerosols interactions in RPV and formation of a new Cs bearing contaminating phase has been shown. This paper analyses the data on aerosol behaviour of Cs and B bearing aerosols when they interact in the gas line, and concentrates on the phenomenon of possible reactions on the liquid-liquid and liquid-gas interface when aerosols are interacting during the large-scale bundle degradation test.
Nguyen, T. H.*; Le Ba, T.*; Tran, C. T.*; Nguyen, T. T.*; Doan, T. T. T.*; Do, V. K.; 渡邉 雅之; Pham, Q. M.*; Hoang, S. T.*; Nguyen, D. V.*; et al.
Hydrometallurgy, 213, p.105933_1 - 105933_11, 2022/08
被引用回数：22 パーセンタイル：87.71(Metallurgy & Metallurgical Engineering)ベトナム・イェンフー希土類精鉱浸出液からトリウム(Th)とウラン(U)を選択的に回収するための連続向流抽出法を系統的に研究した。抽出剤としては、イソパラフィンIP-2028希釈液で調製した一級アミンN1923を用いた。トリウムとウランは、連続ミキサーセトラエクストラクション,スクラビング,逆エクストラクションによって確立された湿式製錬サイクルで選択的に回収され、ラボスケールで実施された。有機相と水相の体積比(O/A比)を管理することにより、ThとUの所望の純度を達成することができる。逆抽出液とラフィネートからそれぞれ高純度のThとUを回収することができ、その後の核物質処理に十分な特性を有している。
Pham, V. H.; 倉田 正輝; Steinbrueck, M.*
Thermo (Internet), 1(2), p.151 - 167, 2021/09
Since the nuclear accident at Fukushima Daiichi Nuclear Power Station in 2011, a considerable number of studies have been conducted to develop accident tolerant fuel (ATF) claddings for safety enhancement of light water reactors. Among many potential ATF claddings, silicon carbide is one of the most promising candidates with many superior features suitable for nuclear applications. In spite of many potential benefits of SiC cladding, there are some concerns over the oxidation/corrosion resistance of the cladding, especially at extreme temperatures (up to 2000C) in severe accidents. However, the study of SiC steam oxidation in conventional test facilities in water vapor atmospheres at temperatures above 1600C is very challenging. In recent years, several efforts have been made to modify existing or to develop new advanced test facilities to perform material oxidation tests in steam environments typical of severe accident conditions. In this article, the authors outline the features of SiC oxidation/corrosion at high temperatures, as well as the developments of advanced test facilities in their laboratories, and, finally, give some of the current advances in understanding based on recent data obtained from those advanced test facilities.
C studied by laser heatingPham, V. H.; 永江 勇二; 倉田 正輝; Bottomley, D.; 古本 健一郎*
Journal of Nuclear Materials, 529, p.151939_1 - 151939_8, 2020/02
被引用回数：21 パーセンタイル：89.74(Materials Science, Multidisciplinary)As expected for accident tolerant fuels, investigation of steam oxidation for silicon carbide under the conditions beyond design basis accident scenarios is needed. Many studies focused on steam oxidation of SiC at temperatures up 1600C have been conducted and reported in the literature. However, behavior of SiC in steam at temperatures above 1600C still remains unclear. To complete this task, we have designed and manufactured a laser heating facility for steam oxidation at extreme temperatures. With the facility, we report the first results on the steam oxidation behavior of SiC at temperatures range of 1400-1800C for short term exposure of 1-7 h under atmospheric pressure. Based on the mass change of SiC samples, parabolic oxidation rate and linear volatilization rate were calculated. The oxidation layer appears to be maintained at 1800C in steam, but the bubble formation phenomenon suggests other volatilization reactions may limit its life.
Pham, V. H.; 永江 勇二; 倉田 正輝; 古本 健一郎*; 佐藤 寿樹*; 石橋 良*; 山下 真一郎
Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.670 - 674, 2019/09
Silicon carbide (SiC) has recently attracted much attention as a potential material for accident tolerant fuel cladding. To investigate the performance of SiC in severe accident conditions, study of steam oxidation at high temperatures is necessary. However, the study focusing on steam oxidation of SiC at temperatures above 1600C is still certainly limited due to lack of test facilities. With the extreme oxidation/corrosion environment in steam at high temperatures, current refractory materials such as alumina and zirconia would not survive during the tests. Application of laser heating technique could be a great solution for this problem. Using laser heating technique, we can localize the heat and focus them on the test sample only. In this study, we developed a laser heating facility to investigate high-temperature oxidation of SiC in steam at temperature range of 1400-1800C for 1-7 h. The oxidation kinetics is then being studied based on the weight gain and observation on cross-sectioned surface of tested sample using field emission scanning electron microscope. Off-gas measurement of hydrogen (H) and carbon monoxide (CO) generated during the test is also being conducted via a sensor gas chromatography. Current results showed that the SiC sample experienced a mass loss process which obeyed paralinear laws. Parabolic oxidation rate constant and linear volatilization rate constant of the process were calculated from the mass change of the samples. The apparent activation energy of the parabolic oxidation process was calculated to be 85 kJ.mol
. The data of the study also indicated that the mass change of SiC under the investigated conditions reached to its steady stage where hydrogen generation became stable. Above 1800C, a unique bubble formation on sample surface was recorded.
山崎 宰春; Pshenichnikov, A.; Pham, V. H.; 永江 勇二; 倉田 正輝; 徳島 二之*; 青見 雅樹*; 坂本 寛*
Proceedings of Annual Topical Meeting on Reactor Fuel Performance (TopFuel 2018) (Internet), 8 Pages, 2018/10
燃料集合体の酸化及び水素吸収はその後の事故進展挙動に影響を与えることから、PWR燃料集合体では、実効的な水蒸気流量としてg-HO/sec/rodという単位が導入されており、事故進展評価の重要なパラメータといて用いられている。一方BWRにおいては、燃料集合体の構成がPWRとは異なることにより、PWRで用いられている規格化された水蒸気流量ではチャンネルボックスの内外での酸化及び水素吸収の差が正確に評価できない。そのため、PWRで用いられているg-HO/sec/rodという規格化された水蒸気流量に代わる、適切な評価パラメータがBWRでも必要である。そこで、ジルカロイの水蒸気枯渇条件での酸化及び水素吸収データを取得するため、実機を模擬したBWRバンドル試験体を用いて高温酸化試験を行なった。BWRにおける水蒸気流量を規格化するため、水蒸気流路断面積を考慮したパラメータを検討した。
CPham, V. H.; 永江 勇二; 倉田 正輝
Proceedings of Annual Topical Meeting on Reactor Fuel Performance (TopFuel 2018) (Internet), 6 Pages, 2018/10
High temperature interaction of chemical vapor deposition SiC with steam was investigated at 1700-1800C for 0.1-3 h in a mixture of steam and argon gas containing 98% of steam at 1 atm. At the investigated conditions, although a dense oxide layer was observed on sample surface, significant mass loss of SiC occurred. Below 1700C, the oxidation kinetics seems to follow the para-linear laws. The apparent activation calculated based on the data of this study is to be 370 kJ/mol. Rapid degradation and bubbling of SiC at 1800C were observed after 1 h oxidation. This suggested that chemical interaction behaviours above 1700C might be changed due to the liquefaction of silica.
Pham, V. H.; 石橋 良*; 佐々木 政名*; 根本 義之; 山下 真一郎
no journal, ,
Silicon carbide (SiC) is one of most potential candidates for accident tolerant fuel claddings. Among these candidates, SiC shows the best performance under severe accident conditions in high-temperature steam. However, during normal operation, there are some concerns on the dilution of silica from SiC in aqueous environment under long-term operation/irradiation. In order to improve its performance under normal operation, coating of Titanium-layer on SiC cladding was proposed. To study the influence of the Ti-coating layer on oxidation resistance of SiC cladding and its performance at high-temperature steam, oxidation tests of Ti-coated SiC samples in steam up to 1500C were carried out. Results of this study showed that Ti coating layer did not negatively affect much on the oxidation resistance of the SiC cladding. No spallation/lamination was observed on sample surface or coating layer, even on the sample after oxidation at 1500C in steam for two hours. Oxidation kinetics of the Ti-coated SiC seemed to follow two different oxidation states. Comparison of oxidation tests among Zry-4 and SiC and Ti-coated SiC showed that SiC cladding in general and Ti-coated SiC cladding specifically exhibited a considerably lower oxidation rate than Zry-4 cladding. This lower oxidation rate would benefit in resulting less exothermic heat and less hydrogen generation in severe accident events.
河合 慶人*; 根本 義之; 藤村 由希; 近藤 啓悦; 阿部 陽介; Mohamad, A. B.; Pham, V. H.; 石川 法人; 石島 暖大; 井岡 郁夫; et al.
no journal, ,
現行のジルカロイ被覆管よりも事故耐性に優れた事故耐性燃料(ATF)被覆管の開発が進められている。その一つに被覆管外面にCrをコーティングしたコーティング被覆管があり、高温水蒸気中での耐酸化性の向上が見込まれている。しかし、冷却水損失事故(LOCA)時には被覆管が破裂し、コーティングされていない被覆管内面も酸化することが予想される。そこで、本研究ではジルカロイ4被覆管及びその外面にCrコーティングを施したコーティング被覆管を用いて高温水蒸気中での酸化試験を行い、酸化挙動、水素吸収挙動及び機械特性の違いを検討した。
CPham, V. H.; 永江 勇二; 倉田 正輝
no journal, ,
Silicon carbide (SiC) has recently attracted much attention as a potential material for accident tolerant fuel cladding. High-temperature interaction of SiC at temperature range below 1600C has been studied by various authors. As expected for enhanced accident tolerant fuel cladding, high-temperature interaction of SiC must be also investigated at temperatures above 1600C. In this study, we investigate high-temperature interaction of SiC in steam at temperature range of 1700
1800C using laser heating furnace. The oxidation kinetics is then studied based on the weight change and observation on cross-sectioned surface of tested sample using field emission scanning electron microscope. Off-gas measurement of hydrogen (H) and carbon monoxide (CO) generated during the test was also conducted via sensor gas chromatography.
山崎 宰春; Pshenichnikov, A.; Pham, V. H.; 永江 勇二; 倉田 正輝
no journal, ,
燃料集合体の酸化及び水素吸収はその後の事故進展挙動に影響を与えることから、PWR燃料集合体では、実効的な水蒸気流量としてg-HO/sec/rodという1rodあたりの単位が導入されており、事故進展評価の重要なパラメータとして用いられている。一方BWRにおいては、燃料集合体の構成がPWRとは異なることにより、PWRで用いられている1rodあたりの水蒸気流量ではチャンネルボックスの内外での酸化及び水素吸収の差が正確に評価できない。そのため、PWRで用いられている規格化された水蒸気流量に代わる、適切な評価パラメータがBWRでも必要である。そこで、ジルカロイの水蒸気枯渇条件での酸化及び水素吸収データを取得するため、4本の燃料棒をチャンネルボックスで囲んだ試験体を用いて水蒸気枯渇条件にて高温酸化試験を行なった。BWRにおける水蒸気流量を規格化するため、水蒸気流路断面積を考慮したパラメータを検討した。
C under different steam flow ratePham, V. H.; 永江 勇二; 倉田 正輝; 石橋 良*
no journal, ,
Since the severe accident at Fukushima Daiichi Nuclear Power Plant, development of accident tolerant fuel claddings such SiC has been intensively discussed. However, application of SiC as fuel claddings has raised some concerns over its performance under severe accident conditions in steam. In this study, investigation of steam oxidation for SiC at 1400-1600C under 0.1 and 3 g/min steam flow rate was performed using newly developed laser heating facility. Results of the investigation showed that the SiC experienced a mass gain behavior under 0.1 g/min steam flow rate. Whereas, it suffered a mass loss under 3 g/min steam flow rate. Based on the mass change data obtained in the investigation, reaction rate constants and activation energy of the process were calculated and reported.
C at elevated temperaturesPham, V. H.; 松浦 傑*; 南口 誠*; 永江 勇二; 倉田 正輝
no journal, ,
In this study, soaking experiments of Zry plates in molten SS-BC were conducted to investigate the recession rate of Zry plates in molten SS-BC at 1175-1225C. The molten SS-BC mixture was prepared by heat-treatment at 1400C for 12 h of a powder mixture containing 5 mol% BC and stainless steel. After decreasing temperature to the testing temperatures, Zry plates were soaked in the molten mixture for 0-60 min. After soaking tests, the Zry plates were pulled out of the molten mixture. The remaining thickness of Zry plates after the tests were measured by using optical microscope. To understand the influences of alloying elements in Zry and SS, three other sets of experiments (Zr plates in Fe-BC, Zr plates in SS-BC and Zry plates in Fe-BC) were also conducted. Results of the study indicated that the thickness of Zry plates decreased linearly with increase of soaking duration. The recession rate of Zry plates was increase with increase of testing temperatures. The value of apparent activation energy on the thickness recession rate of Zry plates was determined to be 333 kJ/mol. The alloying elements in SS showed a positive effect on suppression of Zry corrosion. In contrast, the alloying elements in Zry showed a negative effect on the process.
Mohamad, A. B.; 根本 義之; 相馬 康孝; 石島 暖大; 佐藤 智徳; 井岡 郁夫; Pham, V. H.; 三輪 周平; 中島 邦久; 加治 芳行; et al.
no journal, ,
ATF等の新型燃料実用化においては、関連技術開発やそれらの基となる科学的知見の取得及び拡充が不可欠である。原子力機構は、照射試験実施による燃料ふるまい解析技術基盤の構築のための研究開発を行い、長期を要する開発において、開発内容やスケジュールの予見性向上に貢献していくべきと認識している。このため、実装化が最も早いCrコーティング被覆管に関して、燃料ふるまいのメカニズムに立ち返り、「長期照射時の影響」「事故時影響」に関する科学的知見を拡充することを目的とした基礎基盤研究計画を立案し、研究をすすめている。本発表では各研究項目の内容や期待される成果、これまでに得られた結果等を紹介する。
CPham, V. H.; 永江 勇二; 倉田 正輝; 古本 健一郎*; 佐藤 寿樹*; 石橋 良*; 山下 真一郎
no journal, ,
Silicon carbide has been considered as a potential candidate for fuel cladding. Many studies have been conducted to investigate the steam oxidation of SiC at temperatures below 1600C. However, the steam oxidation behavior of SiC at temperatures above 1600C remained unclear due to the lack of test facilities. In this study, we investigated the steam oxidation of SiC at temperatures ranging from 1400-1800C using a newly developed laser heating facility.
Mohamad, A. B.; 根本 義之; 相馬 康孝; 石島 暖大; 佐藤 智徳; 井岡 郁夫; Pham, V. H.; 三輪 周平; 中島 邦久; 加治 芳行; et al.
no journal, ,
原子力機構(JAEA)では事故耐性の向上を目指した燃料被覆管の実用化に資する基礎研究の一環として、各種コーティング被覆管の特性評価を進めている。講演では全体概要の他、特性評価試験に用いることを目的としたJAEAでの新規装置開発の状況、高温水蒸気酸化特性評価試験の結果等について紹介する。
Pham, V. H.; 石橋 良*; 佐々木 政名*; 根本 義之; 山下 真一郎
no journal, ,
SiCは高温水蒸気中での耐酸化性と被覆管の健全性の点で、事故耐性燃料被覆管の有力な候補の一つである。しかし、炉内での適用を考えた場合、長期間の腐食環境下での水中へのSiOの溶出が懸念される。そこで、通常運転時の耐食性を向上させるために、SiC上にTi層を被覆することが提案された。本研究では、1200-1500CにおけるTi被覆SiCの酸化挙動と酸化速度論を熱天秤装置を用いて調べた。その結果に基づき、SiCの酸化速度論と挙動に対するTi被覆層の影響について議論し、報告する。
Mohamad, A. B.; 山下 真一郎; 相馬 康孝; 根本 義之; Pham, V. H.; 阿部 陽介; 井岡 郁夫; 佐藤 智徳; 石島 暖大; 三輪 周平; et al.
no journal, ,
Accident tolerant fuel, ATF, development has become one of the interest topics in the nuclear field recently. In the 4th ATF Workshop, the purpose is to have a technical discussion with a view to domestic readiness by obtaining suggestions among nuclear related organisations including NRA in domestic ATF development. JAEA, as the project coordinator in Japan, will provide an overview of the ATF development currently underway overseas, e.g. the readiness of Cr-coated Zry cladding developed by Framatome and Westinghouse, where the lead test assembly has been completed. An overview of the Japanese ATF development will be given, highlighting the current status and the issues we are currently facing in the development such as the readiness of irradiation testing at Japan. In addition, JAEA, a part of the project coordinator, JAEA also conducted research and development with the cooperation of stakeholders. An overview of R&D under different phenomena with a final goal of transferring experimental data into modelling will be an example of the ongoing work at JAEA. Finally, JAEA hopes to accelerate the development of ATF in Japan with the full cooperation of all members.
