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Nakamura, Hironori*; Hayakawa, Satoshi*; Shibata, Akihiro*; Sasa, Kyohei*; Yamano, Hidemasa; Kubo, Shigenobu
Proceedings of 12th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS12) (Internet), 7 Pages, 2022/10
In order to evaluate long-term coolablity of the debris-bed with decay heat, a three-dimensional calculation method coupled with the debris bed module was developed in this study. The coupled code calculation results show that natural circulation of the coolant between the hot pool and the cold pool is established through the four intermediate heat exchangers after the activation of the dipped direct heat exchangers. The cold pool with the debris-bed is continually cooled not only by the natural circulation flow, but also by heat transfer to the hot pool through the plenum separation plate between the hot pool and the cold pool. The effect of the three-dimensional flow field around the core catcher on the temperature in the debris-bed is about 20K under the current calculation condition.
Yamano, Hidemasa; Kubo, Shigenobu; Sasa, Kyohei*; Shibata, Akihiro*; Hourcade, E.*; Dirat, J. F.*
Proceedings of 29th International Conference on Nuclear Engineering (ICONE 29) (Internet), 9 Pages, 2022/08
This paper describes coolability evaluations of a debris bed with a variety of decay heat removal system (DHRS) operating conditions with a whole vessel model assuming fuel accumulation on the core catcher in a short term. The evaluation tool is a one-dimensional plant dynamics code, Super-COPD, with a debris bed module. The coolability evaluations have indicated that the current core catcher design secures sufficient natural circulation flows around the core catcher to ensure the debris bed cooling when at least one circuit of DHRS was activated. Sensitivity analyses under a pessimistic condition have shown that the debris bed is coolable with at least one circuit of improved DHRS even if most of fuel accumulates on the core catcher in a short term.
Sheikh, Md. A. R.*; Son, E.*; Kamiyama, Motoki*; Morioka, Toru*; Matsumoto, Tatsuya*; Morita, Koji*; Matsuba, Kenichi; Kamiyama, Kenji; Suzuki, Toru*
Journal of Nuclear Science and Technology, 55(6), p.623 - 633, 2018/06
Times Cited Count：14 Percentile：79.66(Nuclear Science & Technology)During core-disruptive accidents in sodium-cooled fast reactors, the sedimentation behavior of fragmented debris is crucial for in-vessel retention. The height of the beds formed may influence both the cooling of the bed and the neutronic characteristics. To develop an experimental database of bed formation behavior, a series of experiments using simulant materials, namely, Al
O
, ZrO, and stainless steel, were performed under gravity-driven discharge of solid particles from a nozzle into a quiescent cylindrical water pool. The bed height was measured for particles of different size, density, and sphericity, and an injection nozzle with varying diameter, injection velocity, and injection height. From these experiments, an empirical correlation was established to predict the bed height for both homogeneous and mixed particles for the different properties. This correlation reproduces reasonably well the experimental trend in bed height.
Matsumoto, Toshinori; Kawabe, Ryuhei; Sugiyama, Tomoyuki; Maruyama, Yu
Proceedings of 10th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-10) (USB Flash Drive), 9 Pages, 2016/11
During severe accident at nuclear power stations, molten core material jet could be discharged from the reactor pressure vessel into the water pool formed at the pedestal or cavity in the containment vessel. To improve the JASMINE code, The method for determining particle diameters which follow the Rosin-Rammler distribution was implemented. The jet breakup experiments, DEFOR-A conducted by KTH (Royal Institute of Technology, Sweden) were analyzed with the code. The influence of the experimental conditions, such as water subcooling, melt jet diameter and superheat were discussed. A crust layer formation model was also implemented in the code. The analyses using the model were carried out for the melt spreading experiments, PULiMS conducted by KTH. The spreading area was overestimated. Further improvement of the melt spreading model were discussed to close the gaps by introducing additional models such as heat conduction in the substrate materials, void formed inside the melt and so on.
Sugimoto, Jun; Hashimoto, Kazuichiro; Yamano, N.; Maruyama, Yu
Nihon Genshiryoku Gakkai "Genshiro Kakuno Yoki Shinraisei Jissho Shiken Ni Kansuru Chosa Hokokusho, Heisei-5-Nendo", 0, p.3 - 192, 1994/00
no abstracts in English
Maruyama, Yu; Abe, Yutaka; *; Soda, Kunihisa
JAERI-M 89-054, 142 Pages, 1989/05
no abstracts in English
Maruyama, Yu; Abe, Yutaka; Yamano, N.; Soda, Kunihisa
JAERI-M 88-157, 56 Pages, 1988/08
no abstracts in English
Yamano, Norihiro; Maruyama, Yu; Abe, Yutaka; Soda, Kunihisa
AIChE Symp.Ser., 83(257), p.341 - 346, 1987/00
Experiments to investigate the effect of coolant injection from the bottom of a devris bed have been performed, and an analytical model has been developed.
Kamiyama, Motoki*; Deguchi, Ryohei*; Morioka, Toru*; Matsumoto, Tatsuya*; Morita, Koji*; Matsuba, Kenichi; Kamiyama, Kenji; Suzuki, Toru
no journal, ,
In order to clarify sedimentation behavior of fuel debris during core disruptive accidents in sodium-cooled fast reactors, fundamental experiments were carried out, where solid particles simulating fuel debris were injected into a water pool. Based on the experimental results, sedimentation behavior and bed formation of different particles in properties were characterized.
Matsumoto, Toshinori; Kawabe, Ryuhei; Sugiyama, Tomoyuki; Maruyama, Yu
no journal, ,
no abstracts in English
Sakurada, Keishi*; Kawakami, Taira*; Sakashita, Hiroto*; Ono, Ayako; Yoshida, Hiroyuki
no journal, ,
This study measured the dryout heat fluxes for bottom heated debris beds, where small spherical particles were placed on a 75mm diameter heating surface. The data were obtained by varying the particle size in the range of 3 to 10mm, and compared with the predicted results with the one dimensional model proposed by Lipinski.
Sakurada, Keishi*; Kawakami, Taira*; Sakashita, Hiroto*; Ono, Ayako; Yoshida, Hiroyuki
no journal, ,
This study measured the dryout heat fluxes on a bottom surface for bottom and volume heated debris beds, where small spherical metal particles were placed on a 75 mm diameter heating surface and internally heated by induction heating. The data were obtained by varying the particle size and the volumetric heated rate, and compared with the available correlations.
Kawakami, Taira*; Sakurada, Keishi*; Sakashita, Hiroto*; Ono, Ayako; Yoshida, Hiroyuki
no journal, ,
The effect of height and density of accumulated particles on the critical heat flux was investigated on the heating surface, where the particles were accumulated, in order to investigate the cooling process of debris under the severe accident. The thermal-hydraulic behavior on the heating surface was visualized from the backsides of heating surface made of glass.
Kawakami, Taira*; Sakashita, Hiroto*; Ono, Ayako; Yoshida, Hiroyuki
no journal, ,
Understanding the boiling heat transfer characteristics in debris beds is indispensable to assess the coolability of molten debris at severe accident. However, the trigger mechanism of the critical heat flux on the bottom heated debris beds has not been fully elucidated. This study performed the visualization measurements using a transparent heating surface on which small particles are accumulated. The boiling behaviors were observed via a total reflection technique, and effects of particle size on dryout and rewetting process of the heating surface were examined.
Kikuchi, Wataru*; Akiba, Miyuki*; Hotta, Akitoshi*; Alexander, K.*; Walter, V.*; Sevostian, B.*; Matsumoto, Toshinori
no journal, ,
To develop the analytical models for jet breakup and debris bed formation, we are conducting experiments that simulate these behaviors. Various uncertainty items associate to the experiment were clarified, and the reflection in the analysis model was examined.
Nakamura, Hironori*; Shibata, Akihiro*; Hayakawa, Satoshi*; Yamano, Hidemasa; Kubo, Shigenobu
no journal, ,
The coolablity of the debris-bed on a core catcher was evaluated using a three-dimensional CFD code coupled with the debris bed module in this study. The coupled code calculation results showed the prospect to attain a long-term stable cooling.
