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Mohamad, A. B.; 宇田川 豊
Nuclear Technology, 210(2), p.245 - 260, 2024/02
被引用回数:2 パーセンタイル:57.39(Nuclear Science & Technology)In the Power to Melt and Maneuverability (P2M) project, a simulation exercise on two past power ramp experiments xM3 on medium burn-up rod and HBC4 on high burn-up rod were performed with the fuel performance code FEMAXI-8 to investigate the fuel behavior under high power and high-temperature conditions toward centerline fuel melting. In order to treat fuel melting, empirical melting temperature models have been incorporated into the FEMAXI-8 code. The present analysis gave reasonable predictions not only on cladding deformation but also on the fuel melting behavior of the HBC4 rod, in which the UO liquidus temperature was reached during the transient. On the other hand, model improvement appeared to be needed for a more accurate treatment of fuel melting behavior of the xM3 rod, in which fuel center temperature reached solidus line, whereas may not reached liquidus line. A reasonable agreement of estimated FGR with the measurement suggested that the high temperature FGR at the given conditions are essentially temperature dependent phenomenon: rate-limited primarily by thermally activated elementary processes such as fission gas diffusion.
Mohamad, A. B.; 根本 義之; 古本 健一郎*; 岡田 裕史*; 佐藤 大樹*
Corrosion Science, 224, p.111540_1 - 111540_15, 2023/11
被引用回数:2 パーセンタイル:33.88(Materials Science, Multidisciplinary)The steam oxidation test on the Cr-coated Zry cladding was studied up to 1400C to understand the oxidation behavior under the accidental conditions. The double-sided oxidation test study showed that Cr coating can protect Zry cladding at 1200
C within 5 min. Cr coating has a protective effect on the Zry cladding up to 1200
C in a steam environment. However, in the oxidation test up to 1200
C/30 min and 1300
C/5 min, Cr coating can no longer protect Zry cladding. Furthermore, at 1300
C, the intermetallic phase of the Zr(Cr, Fe)
phase that precipitated within the Zry substrate formed as globule microstructures with Fe enrichment. In addition, the transition of the intermetallic phase within the Zry substrate from the solid to the pre-liquid and liquid phases was observed, where it was determined at 1350
C/60 min and 1400
C/30 min within the ZrO
phase (outer side region). The oxidation of the Zr(Cr, Fe)
interlayer was also determined in this study, where it resulted in the formation of the oxide phase of Cr, Zr, and Fe. It is worth mentioning that further experiments, such as mechanical testing and modeling, should be considered to support the degradation of the Cr-coated Zry cladding mainly when the liquid phase of the intermetallic phase is obtained for beyond design-basis accident environment.
Mohamad, A. B.; 中島 邦久; 三輪 周平; 逢坂 正彦
Journal of Nuclear Science and Technology, 60(3), p.215 - 222, 2023/03
被引用回数:0 パーセンタイル:0.00(Nuclear Science & Technology)The distribution of Sr in the reactor would be influenced by a chemical reaction of Sr vapor species with a structural material of internal reactor and fuel cladding materials; stainless steel (SS) or Zircaloy (Zry) cladding during 1F-NPS accident. The chemical interaction between Sr-Zry and Sr-SS has been described. The reaction tests have been performed to investigate the chemical interaction behavior under possible severe accident conditions. The tests have been conducted up to 1523 K under steam atmosphere. It was confirmed that Sr-Zr-O and Sr-Si-O compounds were formed through 2 kinds chemical interactions; gas-solid reaction and liquid-solid reaction. The gas and liquid species of Sr in a good contact with the solid Zry and SS to form Sr-Zr-O and Sr-Si-O compounds, respectively. Sr was deposited onto the Zry and SS surfaces and lead to the formation of reaction product. Thus, this study highlights the possibility that Sr was deposited and retained in the core structure where the temperature was elevated during the accident in the 1F-NPS.
Mohamad, A. B.; 根本 義之; 古本 健一郎*; 岡田 裕史*; 佐藤 大樹*
no journal, ,
The development of Accident Tolerant Fuel (ATF) started with the investigation of new concepts to improve the safety of Light Water Reactors (LWR). It is well known that the Cr coating on Zry cladding has shown improved behaviour under accident conditions and in normal operation. However, many questions remain about the oxidation behaviour of Cr-coated Zry cladding as it approaches the Cr-Zr eutectic temperature. In the present study, the steam oxidation tests were carried out under different oxidation conditions in order to understand the oxidation behaviour of the Cr-coated material mainly above the eutectic temperature. The results obtained showed that the Cr coating can protect the Zry substrate at 1100C to 1200
C/5min. However, at 1200
C/30min, the Cr coating no longer protected the Zry substrate. This is due to the formation of Zr at the Cr grain boundary where it becomes a short path for O diffusion and reacts with the Zry substrate.
阿部 陽介; Mohamad, A. B.; 佐々木 泰祐*; 山下 真一郎; 大久保 成彰; 鵜飼 重治
no journal, ,
軽水炉の事故耐性燃料被覆管として開発中のFe-Cr-Al(ODS)合金では、Crリッチ脆化相('粒子)形成による脆化が危惧されるものの、脆化が発現するCrとAlの組成範囲は未確定で、照射の影響も十分理解されていない。本研究では、Fe-Cr-Al合金を拡散対とした相互拡散熱処理により、連続濃度傾斜を有するコンビナトリアル(コンビネーション(組合せ)とマテリアル(材料)の合成語)試料を作製し、熱時効前後での組成と硬さのハイスループット測定を行うことで、固溶強化や
'粒子生成に対する組成の影響を検討した。SEM/EDSによるCrとAlの2次元濃度測定の結果、得られた傾斜濃度がカバーする組成範囲が、
'粒子の析出境界の決定に必要な組成範囲を概ね満たすことを確認した。拡散熱処理後の硬さデータから固溶強化を検討した結果、冷却速度が遅い場合にスピノーダル分解やAl析出物の形成が示唆された。また、熱時効後の硬さデータから
'粒子の析出境界を精緻に評価した。
根本 義之; 岡田 裕史*; 佐藤 大樹*; Mohamad, A. B.; 井岡 郁夫; 鈴木 恵理子
no journal, ,
従来のジルコニウム合金製被覆管の外表面にクロム(Cr)等のコーティングを施し、事故時高温水蒸気中での耐酸化性を向上させた事故耐性燃料(ATF)被覆管の開発が進められている。本研究ではCrコーティング被覆管の事故時挙動について評価し、今後の開発に資する知見を得るため、酸化挙動の評価を行った。酸化挙動に関しては、LOCA時の被覆管破裂後を想定した両面酸化条件での酸化試験を行った。その結果、6501150
Cの温度域ではいずれの場合もコーティングなしの場合に比較して、コーティングありの場合に、酸化量が低く抑えられて推移する傾向が見られた。
手塚 健一*; 木野 千晶*; 山下 晋; Mohamad, A. B.; 根本 義之
no journal, ,
原子力発電所の過酷事故発生時に水素発生・炉心溶融の進展を抑制することを目的とした事故耐性燃料の開発が進んでおり、PWR用には、CrコーティングしたZr被覆管(Crコーティング被覆管)が検討されている。本研究では、Crコーティング被覆管を用いたATFの事故時挙動を評価するための解析手法を開発した。解析ツールとして、国産のSA解析コードであり、ソースコードに容易にアクセス可能なSAMPSONを用いた。解析の結果、現行被覆管に比べて、Crコーティング被覆管を用いることで、事故模擬条件において有意な水素発生抑制効果を確認することができた。
山下 真一郎; Mohamad, A. B.; 井岡 郁夫; 根本 義之; 川西 智弘; 加治 芳行; 逢坂 正彦; 村上 望*; 大脇 理夫*; 佐々木 政名*; et al.
no journal, ,
日本の事故耐性燃料(ATF)研究開発プログラムは、軽水商用炉の炉心、燃料の評価及び実際の設計、研究開発の経験等を最大限に利用するために国内のプラントメーカ、燃料製造メーカ、大学などと協力し2015年より進められてきている。現在国内で検討されているATF候補材料は、潜在的にPWR及びBWRへの適用が期待できる炭化ケイ素/炭化ケイ素(SiC/SiC)複合材料、BWR向けに開発が進められている酸化物分散によって強化されたFeCrAl鋼、PWR向けCr-コーティングジルカロイ被覆管である。また、被覆管材料に加えて、SiC製のBWR用チャンネルボックスや事故耐性制御棒に関する研究開発も行われている。本講演では、ATFプログラムにおけるJAEAの役割を含めて、現在までの研究開発の進捗状況を概説する。
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。
Journeau, C.*; Bechta, S.*; Komlev, A.*; 倉田 正輝; 多木 寛; 松本 俊慶; Mohamad, A. B.; Barrachin, M.*; Quaini, A.*; Bottomley, D.*; et al.
no journal, ,
The OECD project TCOFF-2 (Thermodynamic Chemistry of Fission Products - Part 2) is an extension of the original project that was part of the near-term projects intended to support the Fukushima Dai-ichi decommissioning efforts. This second part continues to be mainly financed by Japanese Ministry (MEXT) with JAEA-CLADS support. TCOFF2 started in August 2022 and includes certain new material requirements compared to the first TCOFF project. These are increased emphasis on accident tolerant fuels (ATFs), certain actinides and fission products related to volatility/leachability but also certain combinations of the ceramic oxide systems important for MCCI behaviour. Following a PIRT review of phenomena in TCOFF 1, there was in TCOFF2 a Task 1 to prioritise current needs, particularly for relevance to severe accident phenomena and alternative materials (ATFs). This included a re-evaluation and ranking of the thermodynamic systems to make a Systems Identification and Ranking Table (SIRT) for the improvement of the thermodynamic database foreseen in TCOFF2. The further systems for evaluation were then proposed by the partners according to their particular requirements; this resulted in over 150 thermodynamic systems. In the mid-year meeting (June 2023) discussions were made to rationalise these into the most important 20 systems. The rationale for the reduction of systems to this limit will be explained in the talk, both those systems that were omitted as well as those finally included. These systems will then be used as a priority list of work for the experimental call to members that will be launched by the TCOFF-2 project towards the end of the year 2023 with the intention to initiate the first projects soon afterwards.
Mohamad, A. B.; Chien, J.; 井岡 郁夫; 鈴木 恵理子; 近藤 啓悦; 根本 義之; 大久保 成彰; 山下 真一郎; 岡田 裕史*; 佐藤 大樹*
no journal, ,
As a candidate for accident tolerent fuel (ATF) cladding tubes, chromium (Cr) coated Zry cladding tubes are being developed. To realize the Cr-coated Zry cladding for future cladding application, the integrity of this material needs to be confirmed with the reactor environment conditions. In order to understand an effect of irradiation on the Cr-coated Zry cladding, ion irradiation test is carried out on the cross-sectional specimens. In this study, the following content mainly focuses on the microstructural evolution and mechanical behavior induced by ion irradiation in Cr-coated Zry cladding. The 10 MeV-Fe irradiation was chosen to induce the damage on the cross section of the Cr-coated Zry cladding. The sample was irradiated at 350
C and the peak irradiation damage was approximately 30 dpa. TEM-EDS shows that the Fe-enrichment peaks are observed around 15 nm at the interface regions between the coating and the Zry substrate for the sample irradiated up to 30 dpa. In addition, the hardness of irradiated sample is higher compared to that un-irradiated sample as result of irradiation-induced hardening. The details of the irradiation effect on the un- and irradiated Cr-coated Zry cladding will be discussed in detail during the presentation.
Mohamad, A. B.; Chen, J.*; 井岡 郁夫; 山下 真一郎
no journal, ,
ATF概念の一つであるCr-coated Zry被覆管は、現行のZry被覆管外表面に厚さ10m程度のコーティングを施すことで事故時の耐水蒸気酸化特性の改善による安全性の向上のみならず、通常運転時の耐食性改善により経済性も向上することが期待されている。しかしながら、Zry被覆管とCrコーティング層の照射下での界面組織の安定性については、不明な点が多く残されているのが現状である。本研究では、Cr/Zry界面における組織安定性と機械的特性の把握を目的に、QST高崎研のTIARA施設でイオン照射したCrコーティング被覆管断面サンプルの微細組織観察と硬さ測定を実施した。透過型電子顕微鏡観察及び元素マッピングの結果から、Cr/Zry界面にはイオン照射によりFe原子が偏析することが確認された。また、機械的特性評価として実施した硬さ試験からは、コーティングしたCr層の方で著しい照射硬化が確認された。今後は、これらの照射データ等を基に、Cr/Zry界面での照射下事象をモデル化し、燃料ふるまいコードにモデル導入を行っていく予定である。
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.
山下 真一郎; 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; 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各種コーティング技術の研究を行っている。講演では全体概要の他、それらの研究に用いることを目的としたJAEAでの新規の装置開発について紹介する。
山下 真一郎; Mohamad, A. B.; 相馬 康孝; 根本 義之; 井岡 郁夫; 加治 芳行; 逢坂 正彦
no journal, ,
2015年以降、日本の事故耐性燃料(ATF)研究開発プログラムは、国内商用炉の燃料や炉心の設計・評価、研究開発における経験を最大限に活用するため、発電プラントメーカ、燃料メーカや大学と連携し進められてきている。本講演では、同プログラムにおける原子力機構の役割を含めて、現在の研究開発について進捗状況の概要を紹介する。
Mohamad, A. B.; 根本 義之; 古本 健一郎*; 岡田 裕史*; 佐藤 大樹*
no journal, ,
The development of Accident Tolerant Fuel (ATF) was initiated to search for better and new materials to improve the safety of Light Water Reactors (LWRs). It is widely recognized that the Cr coating on Zry cladding has shown an improvement in behavior under accident conditions and in normal operation. However, some issues have been pointed out by experts in the development of Cr coatings: eutectic temperature of Cr-Zr, brittleness of the intermetallic phase, ductility limit after quenching and cracking of the Cr coating. In this presentation, the oxidation behavior of Cr-coated Zr cladding above the eutectic temperature and the mechanical behavior of the intermetallic phase obtained from the small-scale tests are elucidated in detail. From the JAEA high temperature oxidation test, the liquid fraction of the intermetallic phase did not melt the cladding itself, although it was tested above the eutectic temperature. In addition, the hardness of the intermetallic phase is slightly lower than that of the oxygen-stabilized zirconium phase. In the near future, it will be necessary to carry out large scale tests on the Cr-coated Zry cladding in order to better understand the integrity of this cladding material under accident conditions.
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。
Mohamad, A. B.; 岡田 裕史*; 佐藤 大樹*; 井岡 郁夫; 鈴木 恵理子; 根本 義之
no journal, ,
Chromium (Cr) coated zirconium (Zr) based alloy cladding is the promising material for a near term accident tolerant fuel (ATF). Cr-coated Zr based cladding was fabricated by sputtering technique and simulated LOCA tests were conducted up to different high temperatures (1200C to 1350
C). The present work aims to investigate the metallography of Cr-coated Zr cladding after LOCA test. The result showed Cr
O
layers were formed as a protective oxide layer at the outmost layer for all samples. However, Cr-Zr phases were observed for the samples which tested up to 1300
C and 1350
C, seems that the Cr-Zr reaction had occurred at this temperature. In addition, Cr-Zr layer in the sample tested up to 1350
C was thicker than which in the sample tested up 1300
C. In particular, the main phases observed in the cross-sectional area were Cr
O
, Cr, ZrO
, Cr-Zr, and Zr situated from outer to inner of the sample after LOCA test. The details of the microstructure on these samples will be discussed in the presentation.
Mohamad, A. B.; 古本 健一郎; 根本 義之; 井岡 郁夫; 佐藤 大樹*; 岡田 裕史*; 山下 真一郎; 逢坂 正彦
no journal, ,
Chromium (Cr) coated zirconium (Zr) based alloy cladding is the promising material for a near term accident tolerant fuel (ATF). Cr-coated Zr based cladding was fabricated by sputtering technique and HT oxidation tests were conducted up to different high temperatures (1100C to 1400
C). The present work aims to investigate the metallography of Cr-coated Zr cladding after HT steam test. The result showed Cr
O
layers were formed as a protective oxide layer at the outmost layer for all samples. However, Cr-Zr-Fe phases were observed In particular, the main phases observed in the cross-sectional area were Cr
O
, Cr, ZrO
, Cr-Zr, and Zr situated from outer to inner of the sample after HT test. The details of the microstructure and mechanism of these samples will be discussed in the presentation.
Mohamad, A. B.; 根本 義之; 古本 健一郎*; 岡田 裕史*; 佐藤 大樹*
no journal, ,
It is widely recognized that the Cr coating on Zry cladding has shown an improvement in the behavior under accident conditions and normal operation. Many research groups around the world have conducted the high-temperature oxidation and LOCA tests on Cr-coated Zry under accident conditions and explained the degradation phenomena from these tests. Although many literatures have revealed the mechanism and phenomena of the degradation of the Cr-coated, there is still a lack of data on the Zr-Cr-Fe phase or intermetallic phase behavior when the temperature reaches and exceeds the eutectic temperature of Zr-Cr (1332C). In the present study, a high temperature steam oxidation test is carried out from 1100 to 1400
C in order to understand the behavior of Cr-coated Zry as it approaches the eutectic temperature. Fromelectron probe microanalysis, the Fe enrichment of the Zr(Cr,Fe)
phase is identified for the sample tested at 1300
C. In addition, the liquid formation of the Zr(Cr,Fe)
phase is observed at 1300
C.