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Journal Articles

Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors, 1; Project overview and progress until 2018

Yamano, Hidemasa; Takai, Toshihide; Furukawa, Tomohiro; Kikuchi, Shin; Emura, Yuki; Kamiyama, Kenji; Fukuyama, Hiroyuki*; Higashi, Hideo*; Nishi, Tsuyoshi*; Ota, Hiromichi*; et al.

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 10 Pages, 2020/08

One of the key issues in a core disruptive accident (CDA) evaluation in sodium-cooled fast reactors is eutectic reactions between boron carbide (B$$_{4}$$C) and stainless steel (SS) as well as its relocation. Such behaviors have never been simulated in CDA numerical analyses in the past, therefore it is necessary to develop a physical model and incorporate the model into the CDA analysis code. This study focuses on B$$_{4}$$C-SS eutectic melting experiments, thermophysical property measurement of the eutectic melt, and physical model development for the eutectic melting reaction. The eutectic experiments involve the visualization experiments, eutectic reaction rate experiments and material analyses. The thermophysical properties are measured in a range from solid to liquid state. The physical model is developed for a severe accident computer code based on the measured data of the eutectic reaction rate and the physical properties. This paper describes the project overview and progress of experimental and analytical studies conducted until 2018. Specific results in this paper are boron concentration distributions of solidified B$$_{4}$$C-SS eutectic sample in the eutectic melting experiments, which would be used for the validation of the eutectic physical model implemented into the computer code.

Journal Articles

Journal Articles

Development of ODS tempered martensitic steel for high burn up fuel cladding tube of SFR

Otsuka, Satoshi; Tanno, Takashi; Oka, Hiroshi; Yano, Yasuhide; Tachi, Yoshiaki; Kaito, Takeji; Hashidate, Ryuta; Kato, Shoichi; Furukawa, Tomohiro; Ito, Chikara; et al.

2018 GIF Symposium Proceedings (Internet), p.305 - 314, 2020/05

Oxide Dispersion Strengthened (ODS) steel has been developed worldwide as a high-strength and radiation-tolerant steel used for advanced nuclear system. Japan Atomic Energy Agency (JAEA) has been developing ODS steel as the primary candidate material of Sodium cooled Fast Reactor (SFR) high burn-up fuel cladding tube. Application of high burn-up fuel to SFR core can contribute to improvement of economical performance of SFR in conjunction with volume and hazardousness reduction of radioactive waste. This paper described the current status and future prospects of ODS tempered martensitic steel development in JAEA for SFR fuel application.

Journal Articles

Post-test material analysis of eutectic melting reaction of boron carbide and stainless steel

Yamano, Hidemasa; Takai, Toshihide; Furukawa, Tomohiro

Nippon Kikai Gakkai Rombunshu (Internet), 86(883), p.19-00360_1 - 19-00360_13, 2020/03

It is necessary to simulate a eutectic melting reaction and relocation behavior of boron carbide (B$$_{4}$$C) as a control rod material and stainless steel (SS) during a core disruptive accident in an advanced sodium-cooled fast reactor designed in Japan because the B$$_{4}$$C-SS eutectic relocation behavior has a large uncertainty in the reactivity history based on a simple calculation. A physical model simulating the eutectic melting reaction and relocation was developed and implemented into a severe accident simulation code. The developed model must be validated by using test data. To validate the physical model, therefore, the visualization tests of SS-B$$_{4}$$C eutectic melting reaction was carried out by contacting SS melts of several kg with a B$$_{4}$$C pellet heated up to about 1500 $$^{circ}$$C. The tests have shown the eutectic reaction visualization as well as freezing and relocation of the B$$_{4}$$C-SS eutectic in upper part of the solidified test piece due to the density separation. Post-test material analyses by using X-ray diffraction and transmission electron microscope techniques have indicated that FeB appeared at the B$$_{4}$$C-SS contact interface and (Fe,Cr)$$_{2}$$B at the top surface of the test piece. Glow discharge optical emission spectrometry has been applied to quantitative analysis of boron concentration distributions. The boron concentration was high at the upper surface and near the original position of the B$$_{4}$$C pellet.

Journal Articles

Experimental evaluation of wall shear stress in a double contraction nozzle using a water mock-up of a liquid Li target for an intense fusion neutron source

Kondo, Hiroo*; Kanemura, Takuji*; Park, C. H.*; Oyaizu, Makoto*; Hirakawa, Yasushi; Furukawa, Tomohiro

Fusion Engineering and Design, 146(Part A), p.285 - 288, 2019/09

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Herein, the wall shear stress in a double contraction nozzle has been evaluated experimentally to produce a liquid lithium (Li) target as a beam target for intense fusion neutron sources such as the International Fusion Materials Irradiation Facility (IFMIF), the Advanced Fusion Neutron Source (A-FNS), and the DEMO Oriented Neutron Source (DONES). The boundary layer thickness and wall shear stress are essential physical parameters to understand erosion-corrosion by the high-speed liquid Li flow in the nozzle, which is the key component in producing a stable Li target. Therefore, these parameters were experimentally evaluated using an acrylic mock-up of the target assembly. The velocity distribution in the nozzle was measured by a laser-doppler velocimeter and the momentum thickness along the nozzle wall was calculated using an empirical prediction method. The resulting momentum thickness was used to estimate the variation of the wall shear stress along the nozzle wall. Consequently, the wall shear stress was at the maximum in the second convergent section in front of the nozzle exit.

Journal Articles

Thermophysical properties of stainless steel containing 5 mass%B$$_{4}$$C in the solid phase

Takai, Toshihide; Furukawa, Tomohiro; Yamano, Hidemasa

Nuclear Technology, 205(9), p.1164 - 1174, 2019/09

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Journal Articles

A Portable radioactive plume monitor using a silicon photodiode

Tamakuma, Yuki*; Yamada, Ryohei; Iwaoka, Kazuki*; Hosoda, Masahiro*; Kuroki, Tomohiro*; Mizuno, Hiroyuki*; Yamada, Koji*; Furukawa, Masahide*; Tokonami, Shinji*

Perspectives in Science (Internet), 12, p.100414_1 - 100414_4, 2019/09

In this study, a portable radioactive plume monitor using a silicon photodiode was developed for the detection of a radioactive plume (e.g. $$^{131}$$I, $$^{134}$$Cs and $$^{137}$$Cs) in an emergency situation. It was found that the background count rate was proportional to ambient dose equivalent rate and the detection limit for the monitor at 20 $$mu$$Sv h$$^{-1}$$ as an ambient dose equivalent rate was evaluated to be 187 Bq m$$^{-3}$$ using the ISO11929 method. These results suggest that the detection limit for the system can be decreased effectively by lead shielding with optimized thickness.

Journal Articles

Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors, 1; Project overview

Yamano, Hidemasa; Takai, Toshihide; Furukawa, Tomohiro; Kikuchi, Shin; Emura, Yuki; Kamiyama, Kenji; Fukuyama, Hiroyuki*; Higashi, Hideo*; Nishi, Tsuyoshi*; Ota, Hiromichi*; et al.

Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.418 - 427, 2019/09

Eutectic reactions between boron carbide (B$$_{4}$$C) and stainless steel (SS) as well as its relocation are one of the key issues in a core disruptive accident (CDA) evaluation in sodium-cooled fast reactors. Since such behaviors have never been simulated in CDA numerical analyses, it is necessary to develop a physical model and incorporate the model into the CDA analysis code. This study is focusing on B$$_{4}$$C-SS eutectic melting experiments, thermophysical property measurement of the eutectic melt, and physical model development for the eutectic melting reaction. The eutectic experiments involve the visualization experiments, eutectic reaction rate experiments and material analyses. The thermophysical properties are measured in the range from solid to liquid state. The physical model is developed for a severe accident computer code based on the measured data of the eutectic reaction rate and the physical properties. This paper describes the project overview and progress of experimental and analytical studies by 2017. Specific results in this paper is boron concentration distributions of solidified B$$_{4}$$C-SS eutectic sample in the eutectic melting experiments, which would be used for the validation of the eutectic physical model implemented into the computer code.

Journal Articles

Ultra-high temperature creep rupture and transient burst strength of ODS steel claddings

Yano, Yasuhide; Sekio, Yoshihiro; Tanno, Takashi; Kato, Shoichi; Inoue, Toshihiko; Oka, Hiroshi; Otsuka, Satoshi; Furukawa, Tomohiro; Uwaba, Tomoyuki; Kaito, Takeji; et al.

Journal of Nuclear Materials, 516, p.347 - 353, 2019/04

 Times Cited Count:1 Percentile:100(Materials Science, Multidisciplinary)

9Cr-ODS steel claddings consisting of tempered martensitic matrix, showed prominent creep rupture strength at 1000 $$^{circ}$$C, which surpassed that of heat-resistant austenitic steels although creep rupture strength of tempered martensitic steels is generally lower than that of austenitic steels at high temperatures. The measured creep rupture strength of 9Cr-ODS steel claddings at 1000 $$^{circ}$$C was higher than that from extrapolated creep rupture trend curves formulated using data at temperatures from 650 to 850 $$^{circ}$$C. This superior strength seemed to be owing to transformation of the matrix from the $$alpha$$-phase to the $$gamma$$-phase. The transient burst strengths for 9Cr-ODS steel were much higher than those for 11Cr-ferritic/martensitic steel (PNC-FMS). Cumulative damage fraction analyses suggested that the life fraction rule can be used for the rupture life prediction of 9Cr-ODS steel and PNC-FMS claddings in the transient and accidental events with a certain accuracy.

Journal Articles

Conceptual design and verification of long-distance laser-probe system for Li target diagnostics of intense fusion neutron source

Kondo, Hiroo*; Kanemura, Takuji*; Hirakawa, Yasushi; Furukawa, Tomohiro

Fusion Engineering and Design, 136(Part A), p.24 - 28, 2018/11

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

In the IFMIF-EVEDA project, we designed and constructed the IFMIF-EVEDA Li Test Loop (ELTL), and we performed experiments to validate the stability of the Li target. This project required a diagnostic tool to be developed in order to examine the Li target; as such, we developed a unique laser-based method that we call the laser-probe method; this method combines a high-precision laser distance meter with a statistical data analysis method. Following the successful development of the laser-probe method, we proposes a long-distance-measurement of the laser probe method (long-distance LP method) as a diagnostics tool in off-beam conditions for IFMIF or the relevant neutron sources. In this study, the measurement uncertainty resulting from coherency of the laser in a long-distance-measurement has been verified by using stationary objects and a water jet simulating the liquid Li target.

Journal Articles

Model calculation of Cr dissolution behavior of ODS ferritic steel in high-temperature flowing sodium environment

Otsuka, Satoshi; Tanno, Takashi; Oka, Hiroshi; Yano, Yasuhide; Kato, Shoichi; Furukawa, Tomohiro; Kaito, Takeji

Journal of Nuclear Materials, 505, p.44 - 53, 2018/07

AA2017-0603.pdf:1.7MB

 Times Cited Count:1 Percentile:74.25(Materials Science, Multidisciplinary)

A calculation model was constructed to systematically study the effects of environmental conditions (i.e. Cr concentration in sodium, test temperature, axial temperature gradient of fuel pin, and sodium flow velocity) on Cr dissolution behavior. Chromium dissolution was largely influenced by small changes in Cr concentration (i.e. chemical potential of Cr) in liquid sodium in the model calculation. Chromium concentration in sodium coolant, therefore, should be recognized as a critical parameter for the prediction and management of Cr dissolution behavior in the sodium-cooled fast reactor (SFR) core. Because the fuel column length showed no impact on dissolution behavior in the model calculation, no significant downstream effects possibly take place in the SFR fuel cladding tube due to the much shorter length compared with sodium loops in the SFR plant and the large axial temperature gradient. The calculated profile of Cr concentration along the wall-thickness direction was consistent with that measured in BOR-60 irradiation test where Cr concentration in sodium bulk flow was set at 0.07 wt ppm in the calculation.

Journal Articles

Thermophysical properties of stainless steel containing 5mass%-B$$_{4}$$C in the solid phase

Takai, Toshihide; Furukawa, Tomohiro; Yamano, Hidemasa

Proceedings of 2018 International Congress on Advances in Nuclear Power Plants (ICAPP 2018) (CD-ROM), p.1007 - 1013, 2018/04

Journal Articles

Experimental study on cavitation of a liquid lithium jet for International Fusion Materials Irradiation Facility

Kondo, Hiroo; Kanemura, Takuji*; Furukawa, Tomohiro; Hirakawa, Yasushi; Wakai, Eiichi; Knaster, J.*

Journal of Nuclear Engineering and Radiation Science, 3(4), p.041005_1 - 041005_11, 2017/10

A liquid-Li free-surface stream flowing at 15 m/s under a high vacuum of 10$$^{-3}$$ Pa is to serve as a beam target (Li target) for the planned International Fusion Materials Irradiation Facility (IFMIF) or other intense fusion neutron sources. This study focuses on cavitation-like acoustic noise which was detected in a conduit downstream from the Li target. This noise was measured by using acoustic-emission (AE) sensors that were installed at several locations of the conduit via acoustic wave guides. As a result, we found that cavitation occurred only in a narrow area where the Li target impinged on the downstream conduit.

Journal Articles

Thermodynamic study of gaseous CsBO$$_{2}$$ by Knudsen effusion mass spectrometry

Nakajima, Kunihisa; Takai, Toshihide; Furukawa, Tomohiro; Osaka, Masahiko

Journal of Nuclear Materials, 491, p.183 - 189, 2017/08

 Times Cited Count:2 Percentile:63.18(Materials Science, Multidisciplinary)

One of the main chemical forms of cesium in the gas phase during severe accidents of light water reactor is expected to be cesium metaborate, CsBO$$_{2}$$, by thermodynamic equilibrium calculation considering reaction with boron. But accuracy of the thermodynamic data of gaseous metaborate, CsBO$$_{2}$$(g), has been judged as poor quality. Thus, Knudsen effusion mass spectrometric measurement of CsBO$$_{2}$$ was carried out to obtain reliable thermodynamic data. The evaluated values of standard enthalpy of formation of CsBO$$_{2}$$(g), $$Delta$$$$_{f}$$H$$^{circ}$$$$_{298}$$(CsBO$$_{2}$$,g), by the 2nd and 3rd law treatments are -700.7$$pm$$10.7 kJ/mol and -697.0$$pm$$10.6 kJ/mol, respectively, and agree with each other within the errors, which suggests our data are reliable. Further, it was found that the existing data of the Gibbs energy function and the standard enthalpy of formation agreed well with the values evaluated in this study, which indicates the existing thermodynamic data are also reliable.

Journal Articles

Validation of liquid lithium target stability for an intense neutron source

Kondo, Hiroo; Kanemura, Takuji*; Furukawa, Tomohiro; Hirakawa, Yasushi; Wakai, Eiichi; Knaster, J.*

Nuclear Fusion, 57(6), p.066008_1 - 066008_10, 2017/07

 Times Cited Count:9 Percentile:27.12(Physics, Fluids & Plasmas)

A liquid-Li free-surface stream flowing at 15 m/s under a high vacuum of 10$$^{-3}$$ Pa is to serve as a beam target (Li target) for the planned International Fusion Materials Irradiation Facility (IFMIF) or other intense fusion neutron sources. We determined that the stability of the Li target remained unchanged despite using it for an extended period of 1,561 h. This finding is regarded as a significant step toward the realization of the IFMIF and the potential use of relevant neutron sources such as A-FNS and DONES.

Journal Articles

Ultra-high temperature tensile properties of ODS steel claddings under severe accident conditions

Yano, Yasuhide; Tanno, Takashi; Oka, Hiroshi; Otsuka, Satoshi; Inoue, Toshihiko; Kato, Shoichi; Furukawa, Tomohiro; Uwaba, Tomoyuki; Kaito, Takeji; Ukai, Shigeharu*; et al.

Journal of Nuclear Materials, 487, p.229 - 237, 2017/04

 Times Cited Count:17 Percentile:3.38(Materials Science, Multidisciplinary)

Ultra-high temperature ring tensile tests were carried out to investigate the tensile behavior of oxide dispersion strengthened (ODS) steel claddings and wrapper materials under severe accident conditions; temperatures ranged from room temperature to 1400$$^{circ}$$C which is near the melting point of core materials. The experimental results showed that tensile strength of 9Cr-ODS steel claddings was highest in the core materials at the ultra-high temperatures between 900 and 1200$$^{circ}$$C, but that there was significant degradation in tensile strength of 9Cr-ODS steel claddings above 1200$$^{circ}$$C. This degradation was attributed to grain boundary sliding deformation with $$gamma$$/$$delta$$ transformation, which was associated with reduced ductility. On the other hand, tensile strength of recrystallized 12Cr-ODS and FeCrAl-ODS steel claddings retained its high value above 1200 $$^{circ}$$C unlike the other tested materials. Present study includes the result of "R&D of ODS ferritic steel fuel cladding for maintaining fuel integrity at the high temperature accident condition" entrusted to Hokkaido University by the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT).

Journal Articles

Dissolution behavior of lithium compounds in ethanol

Furukawa, Tomohiro; Hirakawa, Yasushi; Kondo, Hiroo; Kanemura, Takuji

Nuclear Materials and Energy (Internet), 9, p.286 - 291, 2016/12

BB2015-1402.pdf:3.16MB

 Times Cited Count:2 Percentile:69.03(Nuclear Science & Technology)

In order to exchange the components which received irradiation damage during the operation at the International Fusion Materials Irradiation Facility, the adhered lithium, which is partially converted to lithium compounds such as lithium oxide and lithium hydroxide, should be removed from the components. In this study, the dissolution experiments of lithium compounds (lithium nitride, lithium hydroxide, and lithium oxide) were performed in a candidate solvent, allowing the clarification of time and temperature dependence. Based on the results, a cleaning procedure for adhered lithium on the inner surface of the components was proposed.

Journal Articles

Nitrogen hot trap design and manufactures for lithium test loop in IFMIF/EVEDA project

Wakai, Eiichi; Watanabe, Kazuyoshi*; Ito, Yuzuru*; Suzuki, Akihiro*; Terai, Takayuki*; Yagi, Juro*; Kondo, Hiroo; Kanemura, Takuji; Furukawa, Tomohiro; Hirakawa, Yasushi; et al.

Plasma and Fusion Research (Internet), 11, p.2405112_1 - 2405112_4, 2016/11

BB2015-1982.pdf:2.03MB

Journal Articles

Corrosion of 9-12Cr ferritic-martensitic steels in high-temperature CO$$_{2}$$

Rouillard, F.*; Furukawa, Tomohiro

Corrosion Science, 105, p.120 - 132, 2016/04

 Times Cited Count:43 Percentile:3.33(Materials Science, Multidisciplinary)

The high temperature corrosion behavior of two 9Cr and 12Cr ferritic-martensitic steel grades was studied under CO$$_{2}$$ pressure varying from 1 to 250 bar for exposure times up to 8000 h. No breakaway oxidation was observed. 9Cr steel grades suffered from fast parabolic uniform oxidation and fast carburisation. Increasing CO$$_{2}$$ pressure had very little effect on the oxidation rate but increased the carburisation rate. The corrosion behavior of both 12Cr steel grades differed and might be influenced by gas composition, minor elements or surface finish. A corrosion mechanism coupling oxidation and carburisation is proposed.

JAEA Reports

Development of evaluation procedure of vapor species transition behavior; Investigation of applicable measurement technology for estimation of chemical form and physical parameters, and validity verification

Takai, Toshihide; Sato, Isamu*; Yamashita, Shinichiro; Furukawa, Tomohiro

JAEA-Technology 2015-043, 56 Pages, 2016/02

JAEA-Technology-2015-043.pdf:23.14MB

Fundamental research on FP-chemistry for fission product release behaviors under severe accident was carried out for reinforcement of source term evaluation, and implementation of the 1F decommissioning R&D project. There were subjects to clarified (1) FP chemistry behavior between vapor species release and aerosol formation and (2) physical parameters which would be affect subsequent aerosol's chemical behavior, for improvement of FP transport model. Applicability of measuring/analyzing techniques presently used was studied for evaluating foregoing properties. And the validity was verified by trial measurements. In conclusion, Raman spectrometry and high temperature X-ray diffraction were hopeful to determine FP-chemical form against vapor/aerosol species and aerosol species, respectively. Combination use of cascade impactor and scanning type electron microscope with energy-dispersive X-ray spectrometry was hopeful to determine physical parameters of aerosol.

234 (Records 1-20 displayed on this page)