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Prediction of the drying behavior of debris in Fukushima Daiichi Nuclear Power Station for dry storage

仲吉 彬; 鈴木 誠矢; 岡村 信生; 渡部 雅之; 小泉 健治

Journal of Nuclear Science and Technology, 55(10), p.1119 - 1129, 2018/10

 パーセンタイル:100(Nuclear Science & Technology)

Treatment policies for debris from Fukushima Daiichi Nuclear Power Station is not decided, however, any policies may include medium and long term storages of debris. Dry storages may be desirable in terms of costs and handlings, but it is necessary to assess generating hydrogen during storages due to radiolysis of accompanied water with debris before debris storages. Al$$_{2}$$O$$_{3}$$, SiO$$_{2}$$, ZrO$$_{2}$$, UO$$_{2}$$ and cement paste pellets as simulated debris were prepared, which have various porosities and pore size distribution. Weight changes of wet samples were measured at various drying temperatures (100, 200, 300, and 1000$$^{circ}$$C) using a Thermogravimetry, under helium gas flow (50 cc/min) or reduced pressure conditions (reducing pressure rate: 200 Pa in 30 min). From the results, drying curves were evaluated. There is a possibility that cold ceramics can predict drying behaviors of ceramics debris as a simulation because all of the ceramics pellets generally showed similar drying characteristics in this experiment. The cement paste pellets indicated different behavior compared to the ceramics pellets, and the drying time of the cement paste pellets was longer even in 1000$$^{circ}$$C conditions. It is necessary to decide the standard level of the dry state for a drying MCCI products which may be accompanied by concrete.


Corrosion behaviour of FeCrAl-ODS steels in nitric acid solutions with several temperatures

高畠 容子; 安倍 弘; 佐野 雄一; 竹内 正行; 小泉 健治; 坂本 寛*; 山下 真一郎

Proceedings of Annual Topical Meeting on Reactor Fuel Performance (TopFuel 2018) (Internet), 9 Pages, 2018/10

事故耐性軽水炉燃料の燃料被覆管として開発されているFeCrAl-ODS鋼の硝酸腐食評価を、使用済燃料再処理工程に対して燃料被覆管腐食生成物が与える影響を評価するために実施した。3mol/L硝酸における腐食試験を、60$$^{circ}$$C, 80$$^{circ}$$C,沸騰条件において実施し、浸漬試験の試験片に対してはXPS分析を行った。沸騰条件にて最も腐食が進展し、腐食速度は0.22mm/yであった。酸化被膜内のFe割合は減少しており、CrとAlの割合は増加していた。腐食試験の結果、FeCrAl-ODS鋼は高い硝酸腐食耐性を持つため、再処理工程中の溶解工程において許容可能であることを確かめた。


Mechanical properties of cubic (U,Zr)O$$_{2}$$

北垣 徹; 星野 貴紀; 矢野 公彦; 岡村 信生; 小原 宏*; 深澤 哲生*; 小泉 健治

Journal of Nuclear Engineering and Radiation Science, 4(3), p.031011_1 - 031011_7, 2018/07

Evaluation of fuel debris properties is required to develop fuel debris removal tools for the decommissioning of Fukushima Daiichi Nuclear Power Plant (1F). In this research, the mechanical properties of cubic (U,Zr)O$$_{2}$$ samples containing 10-65% ZrO$$_{2}$$ are evaluated. In case of the (U,Zr)O$$_{2}$$ samples containing less than 50% ZrO$$_{2}$$, Vickers hardness and fracture toughness increased, and the elastic modulus decreased slightly with increasing ZrO$$_{2}$$ content. Moreover, all of those values of the (U,Zr)O$$_{2}$$ samples containing 65% ZrO$$_{2}$$ increased slightly compared to (U,Zr)O$$_{2}$$ samples containing 55% ZrO$$_{2}$$. However, higher Zr content (exceeding 50%) has little effect on the mechanical properties. This result indicates that the wear of core-boring bits in the 1F drilling operation will accelerate slightly compared to that in the TMI-2 drilling operation.



照沼 章弘; 三村 竜二; 長島 久雄; 青柳 義孝; 廣川 勝規*; 打它 正人; 石森 有; 桑原 潤; 岡本 久人; 木村 泰久; et al.

JAEA-Review 2016-008, 98 Pages, 2016/07




Mechanical properties of fuel debris for defueling toward decommissioning

星野 貴紀; 北垣 徹; 矢野 公彦; 岡村 信生; 小原 浩史*; 深澤 哲生*; 小泉 健治

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 6 Pages, 2015/05

In the decommissioning of Fukushima Daiichi Nuclear Power Plant (1F), safe and steady defueling work is requested. Before the defueling in 1F, it is necessary to evaluate fuel debris for properties related to the defueling procedure and technology. It is speculated that uranium and zirconium oxide solid solution is one of the major materials of fuel debris in 1F, according to TMI-2 accident experience and the results of past severe accident studies. In this report, mechanical properties of uranium and zirconium oxide solid solution evaluated in the ZrO$$_{2}$$ content range from 10% to 65%.


Sludge behavior in centrifugal contactor operation for nuclear fuel reprocessing

坂本 淳志; 佐野 雄一; 竹内 正行; 岡村 信生; 小泉 健治

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 5 Pages, 2015/05

The Japan Atomic Energy Agency (JAEA) has been developing the centrifugal contactor for spent fuel reprocessing. In this study, we investigated the sludge behavior in centrifugal contactors at three different scales. The operational conditions (the flow rate and rotor speed) were varied. Most insoluble particles such as sludge remained in the rotor via centrifugal force. The capture ratio of sludge in the contactor was measured as a function of particle size at various flow rates, rotor speeds, and contactor scales. The sludge adhered and accumulated inside the rotor as the operational time increased, and the operational conditions influenced the capture ratio of the sludge; a lower flow rate and higher rotor speed increased the capture ratio. The results confirmed that Stokes' law can be applied to estimate the experimental result on the behavior of the capture ratio for centrifugal contactors with different scales.



小栗 英知; 長谷川 和男; 伊藤 崇; 千代 悦司; 平野 耕一郎; 森下 卓俊; 篠崎 信一; 青 寛幸; 大越 清紀; 近藤 恭弘; et al.

Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (インターネット), p.389 - 393, 2014/10



Direction on characterization of fuel debris for defueling process in Fukushima Daiichi Nuclear Power Station

矢野 公彦; 北垣 徹; 池内 宏知; 涌井 遼平; 樋口 英俊; 鍛治 直也; 小泉 健治; 鷲谷 忠博

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.1554 - 1559, 2013/09

For the decommissioning of Fukushima Daiichi Nuclear Power Station (1F), defueling work for the fuel debris in the reactor core of Unit 1-3 is planned to be started within 10 years. Preferential items in the characterization of the fuel debris were identified for the defueling work at 1F, in which the procedure and handling tools were assumed from information of 1F and experience of Three Mile Island Unit 2 (TMI-2) accident. The candidates of defueling tools for 1F were selected from TMI-2 defueling tools. It was found out that they were categorized as 6 groups by their working principles. Important properties on the fuel debris for the defueling were picked up from considering influence of objective materials on their performance. The selected properties are shape, size, density, thermal conductivity, heat capacity, melting point, hardness, elastic modulus, and fracture toughness. In these properties, mechanical properties, i.e. hardness, elastic modulus, fracture toughness were identified as preferential items, because there are few data on that of fuel debris in the past severe accident studies.


Applicability of single mode fiber laser for wrapper tube cutting

涌井 遼平; 北垣 徹; 樋口 英俊; 竹内 正行; 小泉 健治; 鷲谷 忠博

Proceedings of 20th International Conference on Nuclear Engineering and the ASME 2012 Power Conference (ICONE-20 & POWER 2012) (DVD-ROM), 7 Pages, 2012/07

Japan Atomic Energy Agency (JAEA) has been developing a fuel disassembly system with reliability for FBR fuel reprocessing. Laser technology has a high cutting performance and stable operation. However, it was hard to apply to the fuel disassembly system in our previous study, because of pin damage and dross adhesion between a wrapper tube and fuel pins. The advance of the laser cutting technology has recently attracted. Development of single mode fiber laser (SMFL) with small diameter of a beam spot has been especially reported. Then, we believed that it has become possible to prevent the dross adhesion in the disassembly. The main purpose of this study is to reevaluate an applicability of laser for the wrapper tube cutting by the basic cutting tests. Concretely, we researched whether cutting conditions such as SMFL etc, have the effects on dross adhesion and pin damage or not and tried to prevent these original matters. As the result, it was demonstrated that the kerf width of SMFL is still thinner than that of multi mode fiber laser (MMFL). The phenomenon is very important to decrease the amount of dross. Therefore, we confirmed that SMFL is suitable for prevention of the original matters and this experimental results shown the new feasibility method of wrapper tube cutting.


Applications of $$^{3}$$He neutron spin filters on the small-angle neutron scattering spectrometer SANS-J-II

坂口 佳史; 吉良 弘; 奥 隆之; 篠原 武尚; 鈴木 淳市; 酒井 健二; 中村 充孝; 相澤 一也; 新井 正敏; 能田 洋平; et al.

Journal of Physics; Conference Series, 294(1), p.012017_1 - 012017_7, 2011/06

 被引用回数:2 パーセンタイル:25.19

A polarized $$^{3}$$He neutron spin filter has been applied to polarization analysis on the small-angle neutron scattering spectrometer SANS-J-II at JRR-3. Measurements were taken on silver behenate, which has several coherent peaks in the small-angle region with a background of spin incoherent hydrogen scattering. Here we demonstrate that the coherent and spin incoherent scattering were successfully separated by the polarization analysis using the $$^{3}$$He spin filter on the instrument.


Research on glass cells for $$^{3}$$He neutron spin filters

坂口 佳史; 吉良 弘; 奥 隆之; 篠原 武尚; 鈴木 淳市; 酒井 健二; 中村 充孝; 鈴谷 賢太郎; 相澤 一也; 新井 正敏; et al.

Physica B; Condensed Matter, 406(12), p.2443 - 2447, 2011/06

Polarized $$^{3}$$He neutron spin filters have attracted much attention because of their available wide energy range for polarizing neutrons and their large solid-angle. To use $$^{3}$$He neutron spin filters for the experiments, it is necessary to produce glass cells with good quality. For this purpose, we made research on the glass cells from several aspects. Firstly, we investigated on the microscopic structure for several glasses by means of X-ray diffraction measurement and tried to find a good measure of evaluating the quality of the cells in terms of their structure. Secondly, we investigated on the glass window, which the laser beam passes through for optical pumping. Thirdly, the cells should be optimized for the polarized neutron scattering experiments and the background from the cells needs to be evaluated. The scattered intensity from the cell in small-angle neutron scattering will also be presented.


Research on glass cells for $$^{3}$$He neutron spin filters

坂口 佳史; 吉良 弘; 奥 隆之; 篠原 武尚; 鈴木 淳市; 酒井 健二; 中村 充孝; 鈴谷 賢太郎; 相澤 一也; 新井 正敏; et al.

Physica B; Condensed Matter, 406(12), p.2443 - 2447, 2011/06

 被引用回数:1 パーセンタイル:92.65(Physics, Condensed Matter)

Glass cells play an important role in polarized $$^{3}$$He neutron spin filters. To evaluate the scattering and absorption contribution from glass cells during neutron scattering experiments, we measured small-angle scattering and neutron transmission in GE180 and other glasses. To pursue the possibility of being a structural influence on $$^{3}$$He spin relaxation in GE180 glass cells, we performed precise X-ray diffraction measurement using synchrotron radiation at SPring-8. From these measurements, a structural difference was observed among GE180 glasses with different thermal treatments.


Characterization of glasses for $$^{3}$$He neutron spin filter cells

坂口 佳史; 吉良 弘; 奥 隆之; 篠原 武尚; 鈴木 淳市; 酒井 健二; 中村 充孝; 鈴谷 賢太郎; 新井 正敏; 武田 全康; et al.

Nuclear Instruments and Methods in Physics Research A, 634(1, Suppl.), p.S122 - S125, 2011/04

Polarized $$^{3}$$He neutron spin filters are promising neutron polarizers in polarized neutron scattering experiments at facilities with two-dimensional detectors and pulsed neutron source. Although they are now operational at several institutions, it is still desired to be developed. Among required factors for the development, the study on the glasses in the filters is one of the important issues. In this paper, we report our recent investigation on the glass cells such as X-ray diffraction measurements and the measurements of the degree of circular polarization of the transmitted laser light through the glass window in the filter.



飛田 健次; 西尾 敏*; 榎枝 幹男; 中村 博文; 林 巧; 朝倉 伸幸; 宇藤 裕康; 谷川 博康; 西谷 健夫; 礒野 高明; et al.

JAEA-Research 2010-019, 194 Pages, 2010/08


発電実証だけでなく、最終的には経済性までを一段階で見通しうる核融合原型炉SlimCSの概念設計の成果を報告する。核融合の開発では、これまで、1990年に提案されたSSTR(Steady State Tokamak Reactor)が標準的な原型炉概念とされてきたが、本研究はSSTRより軽量化を図るため小規模な中心ソレノイドを採用して炉全体の小型化と低アスペクト比化を図り、高ベータ及び高楕円度(グリーンワルド密度限界を高めうる)を持つ炉心プラズマにより高出力密度を目指した。主要パラメータは、プラズマ主半径5.5m,アスペクト比2.6,楕円度2.0,規格化ベータ値4.3,核融合出力2.95GW,平均中性子壁負荷3MW/m$$^{2}$$とした。この炉概念の技術的成立性を、プラズマ物理,炉構造,ブランケット,超伝導コイル,保守及び建屋の観点から検討した。


高レベル放射性物質研究施設(CPF)における保全活動への取組み,1; 高レベル放射性物質閉じ込め用負圧コントロール弁の経年劣化への対応

小林 雄樹; 高橋 哲郎; 篠崎 忠宏; 小笠原 甲士; 小泉 健治; 中島 靖雄

日本保全学会第7回学術講演会要旨集, p.161 - 166, 2010/07



Development of short stroke shearing technology for FBR fuel pin

樋口 英俊; 小泉 健治; 平野 弘康; 田坂 應幸*; 鷲谷 忠博; 小林 嗣幸*

Journal of Power and Energy Systems (Internet), 4(1), p.244 - 251, 2010/04



Design and fabrication of the FBR fuel disassembly system

北垣 徹; 田坂 應幸; 樋口 英俊; 小泉 健治; 平野 弘康; 鷲谷 忠博; 小林 嗣幸*

Proceedings of 17th International Conference on Nuclear Engineering (ICONE-17) (CD-ROM), 5 Pages, 2009/06



SlimCS; Compact low aspect ratio DEMO reactor with reduced-size central solenoid

飛田 健次; 西尾 敏; 佐藤 正泰; 櫻井 真治; 林 孝夫; 芝間 祐介; 礒野 高明; 榎枝 幹男; 中村 博文; 佐藤 聡; et al.

Nuclear Fusion, 47(8), p.892 - 899, 2007/08

 被引用回数:47 パーセンタイル:11.45(Physics, Fluids & Plasmas)



Concept of compact low aspect ratio Demo reactor, SlimCS

飛田 健次; 西尾 敏; 佐藤 正泰; 櫻井 真治; 林 孝夫; 芝間 祐介; 礒野 高明; 榎枝 幹男; 中村 博文; 佐藤 聡; et al.

Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2006/10

コンパクトな原型炉を実現するための新概念を提案する。原型炉で見通しうる保守的な設計パラメータでありながら、経済的実用炉の設計例ARIES-RS, CRESTと同規模にコンパクトな原型炉が実現できる可能性を示した。本研究で提案する炉SlimCSは、主半径5.5m、アスペクト比2.6、最大磁場16.4T、核融合出力2.95GWの原型炉であり、規格ベータ値2、規格化密度0.4のときにゼロ電気出力、規格ベータ値4.3,規格化密度1.1の定格運転では1GW程度の正味電気出力を発生する。この概念の特徴は、小規模な中心ソレノイド(CS)を設置することによって形状制御等の炉心プラズマにかかわる技術的困難を回避しつつ、トロイダル磁場コイルをできる限り中心軸に近づけて設置し、プラズマを低アスペクト比化したことである。これによりトロイダル磁場コイルの蓄積エネルギーが大幅に減少し、トロイダル磁場コイルの物量、ひいては炉本体の建設コストの削減に寄与しうる。また、低アスペクト比のため高楕円度及び高ベータ限界が期待され、このようなコンパクトな原型炉が構想可能になる。


Design study of mechanical disassembly system for FBR fuel reprocessing

遠矢 優一; 鷲谷 忠博; 小泉 健治; 森田 眞一

Proceedings of 14th International Conference on Nuclear Engineering (ICONE-14) (CD-ROM), 6 Pages, 2006/07


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