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Takai, Toshihide; Furukawa, Tomohiro; Yamano, Hidemasa
Mechanical Engineering Journal (Internet), 8(4), p.20-00540_1 - 20-00540_11, 2021/08
In a core disruptive accident scenario, boron carbide, which is used as a control rod material, may melt below the melting temperature of stainless steel owing to the eutectic reaction with them. The eutectic mixture produced is assumed to extensively relocate in the degraded core, and this behavior plays an important role in significantly reducing the neutronic reactivity. However, these behaviors have never been simulated in previous severe accident analysis. To contribute to the improvement of the core disruptive accident analysis code, the thermophysical properties of the eutectic mixture in the solid state were measured, and regression equations that show the temperature (and boron carbide concentration) dependence are created.
Takai, Toshihide; Furukawa, Tomohiro; Yamano, Hidemasa
Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 6 Pages, 2020/08
C in the solid phaseTakai, Toshihide; Furukawa, Tomohiro; Yamano, Hidemasa
Nuclear Technology, 205(9), p.1164 - 1174, 2019/09
Times Cited Count：7 Percentile：69.27(Nuclear Science & Technology)C addition on thermophysical properties of austenitic stainless steel in a solid stateTakai, Toshihide; Furukawa, Tomohiro; Yamano, Hidemasa
Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.847 - 852, 2019/09
C in the solid phaseTakai, 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
I and 
Cs releases during late phase of Fukushima Daiichi NPP accident by using I/Cs ratio of source terms evaluated reversely by WSPEEDI code with environmental monitoring dataHidaka, Akihide; Yokoyama, Hiroya
Journal of Nuclear Science and Technology, 54(8), p.819 - 829, 2017/08
Times Cited Count：12 Percentile：79.56(Nuclear Science & Technology)To clarify what happened during the Fukushima accident, the phenomena within RPV and the discussion of ties with the environmental monitoring are very important. However, the previous study has not necessarily advanced until the present that passed almost six years from the accident. The present study investigated I and Cs release behaviors during the late phase of the accident based on I/Cs ratio of the source terms that were recently evaluated backward by WSPEEDI code based on environmental monitoring data. The I release from the contaminated water in the basement of 1F2 and 1F3 reactor buildings was evaluated to be about 10% of I source term. The increase in Cs release from March 21 to 23 and from March 30 to 31 could be explained by the release of CsBO
which is formed as a result of chemical reactions of Cs with BC due to re-ascension of the core temperature caused by slight shortage of the core cooling water.
I and Cs releases during late phase of Fukushima Daiichi NPP accident by using I/Cs ratio of source terms evaluated reversely by WSPEEDI code with environmental monitoring data, J. Nucl. Sci. Technol. 2017, Corrected vertical axis of Figure 6Hidaka, Akihide; Yokoyama, Hiroya
Journal of Nuclear Science and Technology, 54(8), P. i, 2017/08
Times Cited Count：0 Percentile：2(Nuclear Science & Technology)no abstracts in English
Yamano, Hidemasa; Suzuki, Toru; Kamiyama, Kenji; Kudo, Isamu*
Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Next Generation Nuclear Systems for Sustainable Development (FR-17) (USB Flash Drive), 11 Pages, 2017/06
This paper describes basic visualization experiments on eutectic reaction and relocation of boron carbide (BC) and stainless steel (SS) under a high temperature condition exceeding 1500
C as well as the importance of such behaviors in molten core during a core disruptive accident in a Generation-IV sodium-cooled fast reactor (750 MWe class) designed in Japan. At first, a reactivity history was calculated using an exact perturbation calculation tool taking into account expected behaviors. This calculation indicated the importance of a relocation behavior of the BC-SS eutectic because its behavior has a large uncertainty in the reactivity history. To clarify this behavior, basic experiments were carried out by visualizing the reaction of a BC pellet contacted with molten SS in a high temperature-heating furnace. The experiments have shown the eutectic reaction visualization as well as freezing and relocation of the BC-SS eutectic in upper part of the solidified test piece due to the density separation.
Di Lemma, F. G.; Miwa, Shuhei; Osaka, Masahiko
JAEA-Review 2016-007, 27 Pages, 2016/03
JAEA-Review-2016-007.pdf:1.88MB
During a nuclear power plant Severe Accident, complex boron melts can be formed, due to interaction of the control rods with the cladding materials. These can affect ultimately the source term assessment. This review will describe the results of previous studies on boron carbide/stainless steel/Zircaloy (BC/SS/Zry) melts, which will finally provide guidance for the needs of future experiments. This review showed that models for the behavior of complex BC/SS/Zry melts are limited, and unsuccessful in simulating core degradation, thus the improvement of the database for BC/SS/Zry melts is needed. Our experimental plan aims in providing thermodynamics and kinetics models for such melts, with the final aim of improving boron modelling in SA codes analysis and of understanding its effect on fission products behavior.
Oba, Hironori; Saeki, Morihisa; Yokoyama, Atsushi
Proceedings of Plasma Science Symposium 2005/22nd Symposium on Plasma Processing (PSS-2005/SPP-22), p.331 - 332, 2005/01
A plasma produced by a XeCl laser ablation of boron compound was investigated using ion probes and a quadrupole mass spectrometer. Although the ablated neutral boron atoms had a natural abundance ratio, the isotope ratio of singly ionized boron atoms having a greatly different from the natural abundance ratio was observed. The observed isotope ratio of boron ions was different from the natural abundance.
C doped CFC under high particle flux with low energyNakamura, Kazuyuki; Dairaku, Masayuki; Akiba, Masato; Okumura, Yoshikazu
Journal of Nuclear Materials, 241-243, p.1142 - 1146, 1997/00
Times Cited Count：9 Percentile：60.21(Materials Science, Multidisciplinary)no abstracts in English
*; Saido, Masahiro; Nakamura, Kazuyuki; Akiba, Masato; ; Goto, Yoshitaka*; *; *; Yamaki, Takahiro*; *; et al.
Journal of Nuclear Materials, 233-237(PT.A), p.781 - 786, 1996/00
Times Cited Count：13 Percentile：72.78(Materials Science, Multidisciplinary)no abstracts in English
W.S.Charlton*; T.A.Parish*; S.Raman*; Shinohara, Nobuo; Ando, Masaki
PHYSOR 96: Int. Conf. on the Physics of Reactors, 3, p.F11 - F20, 1996/00
no abstracts in English
Minato, Kazuo; Fukuda, Kosaku
IAEA-TECDOC-784, 0, p.86 - 91, 1995/01
no abstracts in English
Yamashita, Kiyonobu
Journal of Nuclear Science and Technology, 31(9), p.979 - 985, 1994/09
Times Cited Count：6 Percentile：52.53(Nuclear Science & Technology)no abstracts in English
; ; ; ;
JAERI-M 82-196, 29 Pages, 1982/12
no abstracts in English
;
JAERI-M 9185, 20 Pages, 1980/11
no abstracts in English
Yamano, Hidemasa; Suzuki, Toru; Kamiyama, Kenji; Kudo, Isamu*
no journal, ,
This paper describes basic visualization experiments on eutectic reaction and relocation of boron carbide (BC) and stainless steel (SS) under a high temperature condition exceeding 1500C as well as the importance of such behaviors in molten core during a core disruptive accident in a Generation-IV sodium-cooled fast reactor (750 MWe class) designed in Japan. At first, a reactivity history was calculated using an exact perturbation calculation tool taking into account expected behaviors. This calculation indicated the importance of a relocation behavior of the BC-SS eutectic because its behavior has a large uncertainty in the reactivity history. To clarify this behavior, basic experiments were carried out by visualizing the reaction of a BC pellet contacted with molten SS in a high temperature-heating furnace. The experiments have shown the eutectic reaction visualization as well as freezing and relocation of the BC-SS eutectic in upper part of the solidified test piece due to the density separation.
Nakamura, Kinya*; Ota, Hirokazu*; Takai, Toshihide; Yamano, Hidemasa
no journal, ,
To investigate in-depth redistribution behavior of the constituent elements of BC and SS, electron probe microanalysis was applied to the multi-component interaction products held at 1500C for 8 min approximately in argon gas atmosphere in this study. The results indicated that relatively low-density boron was preferentially diffused the upper surface of the molten SS horizontally to form acicular and high melting point compound (Cr,Fe)B along with the eutectic microstructure composed of (Fe,Cr,Ni) solid solution and (Cr,Fe)B. According to the macroscopic quantitative analysis, average chemical concentration of boron is almost uniform in the horizontal direction regardless of the distance from the BC pellet but decreased toward the bottom in the molten SS monotonously in the vertical direction.
C in the solid stateTakai, Toshihide; Furukawa, Tomohiro; Yamano, Hidemasa
no journal, ,
