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論文

Selective recovery of thorium and uranium from leach solutions of rare earth concentrates in continuous solvent extraction mode with primary amine N1923

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:15 パーセンタイル:85.77(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。

論文

Steam oxidation of silicon carbide at high temperatures for the application as accident tolerant fuel cladding, an overview

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 2000$$^{circ}$$C) in severe accidents. However, the study of SiC steam oxidation in conventional test facilities in water vapor atmospheres at temperatures above 1600$$^{circ}$$C 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.

論文

Oxidation kinetics of silicon carbide in steam at temperature range of 1400 to 1800$$^{circ}$$C studied by laser heating

Pham, 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

AA2019-0197.pdf:1.61MB

 被引用回数:16 パーセンタイル:85.51(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 1600$$^{circ}$$C have been conducted and reported in the literature. However, behavior of SiC in steam at temperatures above 1600$$^{circ}$$C 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 1400-1800$$^{circ}$$C 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 1800$$^{circ}$$C in steam, but the bubble formation phenomenon suggests other volatilization reactions may limit its life.

論文

Oxidation of silicon carbide in steam studied by laser heating

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 1600$$^{circ}$$C 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 1400-1800$$^{circ}$$C 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$$_{2}$$) 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$$^{-1}$$. 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 1800$$^{circ}$$C, a unique bubble formation on sample surface was recorded.

論文

Steam oxidation of silicon carbide at temperatures above 1600$$^{circ}$$C

Pham, 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 1700-1800$$^{circ}$$C 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 1700$$^{circ}$$C, 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 1800$$^{circ}$$C were observed after 1 h oxidation. This suggested that chemical interaction behaviours above 1700$$^{circ}$$C might be changed due to the liquefaction of silica.

論文

High temperature oxidation test of simulated BWR fuel bundle in steam-starved conditions

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-H$$_{2}$$O/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-H$$_{2}$$O/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。

口頭

Steam oxidation of silicon carbide at high temperature up to 1800$$^{circ}$$C

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

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 1600$$^{circ}$$C. However, the steam oxidation behavior of SiC at temperatures above 1600$$^{circ}$$C remained unclear due to the lack of test facilities. In this study, we investigated the steam oxidation of SiC at temperatures ranging from 1400-1800$$^{circ}$$C using a newly developed laser heating facility.

口頭

Development of laser heating facility for steam oxidation at extreme temperatures

倉田 正輝; Pham, V. H.; 永江 勇二

no journal, , 

Since the disaster at Fukushima Daiichi Nuclear Power Plant, development of accident tolerant fuel to manage severe accidents has been proposed. As temperature of fuel rods could reach to temperatures above 2000$$^{circ}$$C during the accident, investigation of oxidation behavior at such temperatures for fuel claddings must be conducted. Nevertheless, there is no test facility capable for operating at such conditions. In this study, we developed a laser heating facility for steam oxidation of cladding materials at extreme temperatures. Main features of the facility are controlled environment, in situ observation, extreme fast heating and cooling rate and off gas analysis. As the heat is focused on the test sample only, the facility can be operated at temperatures above 2000$$^{circ}$$C. Preliminary tests have been conducted for monolithic SiC at 1400-1800$$^{circ}$$C for 1-7 h under 0.96 atm steam partial pressure. Results of the investigation showed that SiC underwent a mass loss which obeyed paralinear laws. Based on the mass change data, parabolic oxidation rate and linear volatilization rate of the process were obtained. The apparent activation energy of the oxidation process was calculated to be 96 kJmol $$^{-1}$$. Bubbling phenomenon was observed on SiC sample surface at 1800$$^{circ}$$C.

口頭

R&D for introducing silicon carbide materials to safety improvement of BWR's core, 5; Influence of steam flow rate on oxidation of SiC at high temperatures

Pham, V. H.; 永江 勇二; 倉田 正輝; 石橋 良*; 山下 真一郎

no journal, , 

In this study, oxidation of SiC under various flow rates of steam was investigated at 1400$$^{circ}$$C using laser heating. Results of the investigation indicated that the mass evolution of SiC underwent a mass gain with 0.1 g/min of steam flow rate. Whereas, the mass evolution experienced a mass loss with 3 g/min of steam. Based on the data of mass change under the investigated conditions, the parabolic and linear rate constants were calculated and reported.

口頭

R&D for introducing silicon carbide materials to safety improvement of BWR's core, 7; Oxidation kinetics of SiC at 1400-1600$$^{circ}$$C under different steam flow rate

Pham, 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 1400-1600$$^{circ}$$C 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.

口頭

JAEAにおけるATF基礎基盤研究

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。

口頭

BWR適用に向けたSiC被覆管の要素技術開発

石橋 良*; 廣坂 和馬*; 池側 智彦*; 柴田 昌利*; 佐々木 政名*; 土屋 暁之*; Pham, V. H.; 倉田 正輝; 根本 義之

no journal, , 

炭化ケイ素(SiC)材料製被覆管を用いた燃料は、高温での安定性に伴う事故耐性が期待される一方、沸騰水型原子炉(BWR)で使用するためには多くの技術課題が残っている。その優れた耐熱性を活かし、BWRの構造と運転条件に適用させるため、SiC被覆管の要素技術の開発に取り組んでいる。その中で、耐食被覆および端栓接合のための技術を重点的に開発してきた。講演では詳細を紹介する。

口頭

事故耐性向上を目指した燃料被覆管のコーティング技術に関する研究,1; JAEAにおける事故耐性コーティング技術研究と装置開発

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。

口頭

Study on coating technic to enhance accident tolerance of fuel cladding, 4; Oxidation behavior of the TiN/TiAlN multilayer coated Zry-4

Pham, V. H.; 根本 義之; 山下 真一郎

no journal, , 

事故耐性向上を目的としてジルコニウム表面にTiN/TiAlNの多層膜のコーティングを行った。本研究ではそれらの試料の高温水蒸気中での酸化試験を行い、また試験後の断面観察等を行った。講演ではその結果について紹介するとともに、今後計画しているその他のコーティング技術についても紹介する。

口頭

Insight on Cs and B aerosols behaviour revealed during the CLADS-MADE-05 simulated BWR bundle degradation test

Pshenichnikov, A.; Zubekhina, B.; 多木 寛; Pham, V. H.

no journal, , 

It is well-known that that Cs aerosols and B aerosols interaction is possible during a severe accident. If it occurs before an interaction with steel and debris it can result in a completely different contaminating phases formation. All the factors can be combined and checked only in an integral large-scale bundle test. JAEA has an experience in making BWR bundle degradation tests using the LEISAN facility. During 13 years after the 1F accidents, JAEA/CLADS has performed CR, CRFCB, CRFCBF and CLADS-MADE large-scale bundle tests. The CLADS-MADE-05 is the next test in the series aiming at understanding the control blade melt propagation and mock-up assembly degradation together with Cs and B containing aerosol release. In the current work, first brief overview of the large-scale test results will be given.

口頭

Multilayer coatings to enhance the performance of Zry cladding as advanced fuel cladding

Pham, V. H.; 根本 義之; 山下 真一郎

no journal, , 

Various coatings ranging from ceramics to metals and alloys have been proposed to enhance the performance of Zry as accident tolerant fuel cladding. Ceramic coatings that formed Al$$_{2}$$O$$_{3}$$ or SiO$$_{2}$$ tend to show better steam oxidation resistance, but exhibit poor performance in long-term corrosion resistance due to their dissolutions of cations in aqueous environments. In the meantime, metals and alloys coatings seemed to have improvements in steam oxidation resistance as well as corrosion resistance in water. Nevertheless, the interdiffusion and eutectic reactions of the metallic coatings and Zry substrate at high temperatures may become a serious concern in the event of severe accident conditions. Multilayer coatings on Zry could be a good solution to achieve maximum benefits of each individual coating layer. In attempt to search for alternative coating solutions to improve the performance of Zry4 cladding, in this study, multi-coating of TiN and TiAlN layers on Zry4 was proposed and fabricated by physical vapor deposition coating technique. After the coating works, oxidation tests of coated Zry4 and uncoated-Zry4 in steam via a thermogravimetric system were conducted at 800-1000 $$^{o}$$C to evaluate the protection effectiveness of the coating layers. Post-test analysis of the oxidized samples was carried out with X-ray diffraction and scanning electron microscope. The results of this investigation showed that oxidation kinetics of TiN/TiAlN coated Zry4 followed linear laws. The coating layers only showed some positive effects on oxidation resistance in steam at 800$$^{circ}$$C. At higher temperatures, the samples with coating layers even exhibited faster oxidation rate than that of the uncoated-Zry4. Horizontal cracking at ZrO$$_{2}$$ zone due to the formation of ZrN is attributed to the main cause of this degradation. Multilayer coating on Zry4 remained under discussion. However, nitrides coatings on Zry4 therefore should be avoid for this application.

口頭

事故耐性向上を目指した燃料被覆管のコーティング技術に関する研究,2-1; JAEAにおける事故耐性コーティング技術研究と装置開発

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。

口頭

Interaction of zircaloy and molten mixture of stainless steel-B$$_{4}$$C at elevated temperatures

Pham, 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-B$$_{4}$$C were conducted to investigate the recession rate of Zry plates in molten SS-B$$_{4}$$C at 1175-1225$$^{circ}$$C. The molten SS-B$$_{4}$$C mixture was prepared by heat-treatment at 1400$$^{circ}$$C for 12 h of a powder mixture containing 5 mol% B$$_{4}$$C 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-B$$_{4}$$C, Zr plates in SS-B$$_{4}$$C and Zry plates in Fe-B$$_{4}$$C) 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.

口頭

Study on coating technic to enhance accident tolerance of fuel cladding II, 4; Steam oxidation of Ti-coated SiC as accident tolerant fuel cladding

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$$_{2}$$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、1200-1500$$^{circ}$$C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。

口頭

High-temperature interaction of silicon carbide with steam above 1600$$^{circ}$$C

Pham, 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 1600$$^{circ}$$C 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 1600$$^{circ}$$C. In this study, we investigate high-temperature interaction of SiC in steam at temperature range of 1700$$sim$$1800$$^{circ}$$C 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$$_{2}$$) and carbon monoxide (CO) generated during the test was also conducted via sensor gas chromatography.

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