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

https://doi.org/10.1016/j.hydromet.2022.105933

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。

Oxidation kinetics of silicon carbide in steam at temperature range of 1400 to 1800C 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

https://doi.org/10.1016/j.jnucmat.2019.151939

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.

Steam oxidation of silicon carbide at temperatures above 1600C

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

https://www.euronuclear.org/events/topfuel/topfuel2018/fullpapers/TopFuel2018-A0026-fullpaper.pdf

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.

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 AlO or SiO 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 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 800C. At higher temperatures, the samples with coating layers even exhibited faster oxidation rate than that of the uncoated-Zry4. Horizontal cracking at ZrO 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.

CrコーティングしたZry4の高温水蒸気中での酸化及び水素吸収挙動

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。

Recession of ZrO scale on fuel tube cladding by the melt of control rod assemble

中島 正太郎*; 松浦 傑*; 南口 誠*; 倉田 正輝; Pham, V. H.

no journal, , 

For a better understanding of the Fukushima-Daiichi Nuclear Power Plant accident, a reaction model of core melting process is very important. In this study, oxidized Zry plates were soaked into molten SS-BC mixture and heated into Ar gas at 1200C. Recession of ZrO scale was observed in the both cases. An oxygen solid solution region in the Zry sample was observed below ZrO scale, although it was not observed in Zry oxidized at 600C in high temperature steam conditions. When oxygen supply from the surrounding was halted, ZrO scale can be reduced at high temperature such as 1200C by oxygen dissolution into Zry inside.

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 2000C 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 2000C. Preliminary tests have been conducted for monolithic SiC at 1400-1800C 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 . Bubbling phenomenon was observed on SiC sample surface at 1800C.

Status of development and overview of R&D in Japan

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.

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。

High-temperature interaction of silicon carbide with steam above 1600C

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 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 17001800C 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.