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Horiguchi, Naoki; Yoshida, Hiroyuki; Kaneko, Akiko*; Abe, Yutaka*
Proceedings of 12th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS12) (Internet), 6 Pages, 2022/10
For safety evaluation of nuclear reactors in severe accidents, it is important to estimate physical quantities of fragments generated from the molten fuel jet, which falls in a pool and breaks up. The evaluation method has been developed for the behavior as liquid jet with hydrodynamic interaction including fuel coolant interaction (FCI). In case of a shallow pool assumed in ex-vessel, the molten fuel jet is assumed to behave as wall-impinging liquid jet and to form liquid film flow spreading on the floor with/without fragmentation. In our research, focusing on hydrodynamic interaction and the transient 3-dimensional spreading on the floor, we have developed the evaluation method by numerical simulation using the two-phase flow simulation code with interface tracking method (TPFIT) developed by JAEA and, the experimental method using the 3D-LIF method in liquid-liquid system for the validation data. In our previous studies, we investigated the wall-impinging liquid jet behavior with fragmentation and observed that the liquid film flow had some characteristic parts transiently. Since it indicates that the quantities change depending on the parts and affect the safety evaluation, it is important to measure the quantities of the fragments generated from each part. This paper explains the measurement of the physical quantities of the fragments generated from each part of the wall-impinging liquid jet in a shallow pool for the validation of the numerical simulation. We conducted an experiment with the 3D-LIF method and segmented the experimental data based on the fragmentation point over the liquid film flow using the dispersed phase tracking method, developed by JAEA. Then, we measured the diameter and amount of the fragments from the segmented experimental data and investigated their changing trend.
Moriyama, Kiyofumi; Nakamura, Hideo; Maruyama, Yu*
Nuclear Engineering and Design, 236(19-21), p.2010 - 2025, 2006/10
Times Cited Count：23 Percentile：82.01(Nuclear Science & Technology)A computer code JASMINE-pre was developed for the prediction of premixing conditions of fuel-coolant interactions and the debris bed formation behavior relevant to severe accidents of light water reactors. JASMINE-pre consists of three melt component models: melt jet, melt particles and melt pool, coupled with a two-phase flow model derived from the ACE-3D code developed at JAERI. Simulations of the FARO corium quenching experiments with a saturated water pool and with a subcooled water pool were performed with JASMINE-pre and 
. JASMINE-pre reproduced the pressurization and fragmentation behaviors observed in the experiments with a reasonable accuracy. The results by pmjet showed qualitatively the same trend with JASMINE-pre in the fragmentation behavior.
Moriyama, Kiyofumi; Maruyama, Yu; Usami, Tsutomu*; Nakamura, Hideo
JAERI-Research 2005-017, 173 Pages, 2005/08
JAERI-Research-2005-017.pdf:11.17MB
A series of experiments on the break-up of high temperature oxide and steel melt jets in a water pool was conducted. The objective was to obtain data for the jet break-up length and size distribution of the droplets produced by the jet break-up, and information on the influence of material properties. Also, we tried to obtain additional information giving a clue to the mechanism governing the melt jet break-up, such as flow intensity of the steam column surrounding the melt jet, and its relation with the droplet size. In the experiments, zirconia-alumina mixture and stainless steel melt jets with diameter 
17mm and velocity 7.8m/s at the water surface were dropped into a deep (2.1m) or shallow (0.6m) water pool with various subcool. From the results of the present experiments and also by referring other experimental data from literature, we obtained empirical correlation equations for the jet break-up length, the fraction of jet broken-up in a shallow pool where the jet was not completely broken-up, and the droplet size.
Moriyama, Kiyofumi; Maruyama, Yu*; Nakamura, Hideo
JAERI-Research 2002-021, 36 Pages, 2002/11
JAERI-Research-2002-021.pdf:6.0MB
Silicon is a material which is easily oxidized like zirconium which is one of the LWR core materials. Also, its steam explosion behavior is a concern in semi-conductor industries where its melt is handled. In this study, steam explosion behavior of silicon melt and contribution of oxidation reaction in a steam explosion were investigated. Two cases of experiments were performed by dropping silicon melt into a water pool and both produced spontaneous steam explosions. Energy conversion ratio was 4--9% which was similar or slightly larger compared with previous experiments with thermite melt. Fragmentation of the melt was finer than previous experiments and the mass median diameter of the debris was 65--85
m. An oxide layer of about 5m thick was fond on the debris surface indicating possibility of oxidation of several % of the melt.
Shibamoto, Yasuteru; Kukita, Yutaka*; Nakamura, Hideo
Nuclear Technology, 139(3), p.205 - 220, 2002/09
Times Cited Count：35 Percentile：87.83(Nuclear Science & Technology)no abstracts in English
Moriyama, Kiyofumi; Nakamura, Hideo; Hirano, Masashi
Nihon Kikai Gakkai Dai-8-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu, p.209 - 214, 2002/06
Through a review of experimental works on steam explosions and consideration on the uncertainty in the methodology for plant scale analysis of each stage of the phenomena, it was identified that the molten jet breakup process in premixing has an important uncertainty caused by lack of experimental knowledge. Based on this perspective, an experimental work are under planning at Japan Atomic Energy Research Institute (JAERI), in which the premixing stage of steam explosions in a deep water pool is modeled by high temperature oxide melts. Melt material and scale of the experiment were examined in terms of the simulation capability of the jet breakup mechanism in a plant scale phenomena. Materials and geometrical scale considered adequate were found.
Nariai, Hideki*
JAERI-Tech 2002-009, 60 Pages, 2002/03
JAERI-Tech-2002-009.pdf:7.73MB
no abstracts in English
Moriyama, Kiyofumi; Maruyama, Yu; Nakamura, Hideo; Hashimoto, Kazuichiro; Kamo, Hideki*; Onuki, Akira; Akimoto, Hajime
Dai-7-Kai Doryoku Enerugi Gijutsu Shimpojiumu Koen Rombunshu (00-11), p.451 - 456, 2000/11
no abstracts in English
JNC TN9400 2000-038, 98 Pages, 2000/04
JNC-TN9400-2000-038.pdf:7.49MB
As an effort in the feasibility study on commercialized Fast Breeder Reactor cycle systems, an evaluation of the measures to prevent the energetic re-criticality in sodium-cooled large MOX core, which is one of the candidates for the commercialized reactor, has been performed. The core disruptive accident analysis of Demonstration FBR showed that the fuel compaction of the molten fuel by radial motion in a large molten core pool had a potential to drive the severe super-prompt re-criticality phenomena in ULOF sequence. ln order to prevent occurrence of the energetic re-criticality, a subassembly with an inner duct and the removal of a part of LAB are suggested based on CMR (Controlled Material Relocation) concept. The objective of this study is the comparison of the effectiveness of CMR among these measures by the analysis using SIMMER-III. The molten fuel in the subassembly with inner duct flows out faster than that from other measures. The subassembly with inner duct will work effectively in preventing energetic re-criticality. Though the molten fuel in the subassembly without a part of LAB flows out a little slower, it is still one of the promising measures. However, the UAB should be also removed from the same pin to prevent the fuel re-entries into the core region due to the pressurization by FCl below the core, unless it disturbs the core performance. The effect of the axial fuel length of the center pin to CMR behavior is small, compared to the effect of the existence of UAB.
Shibamoto, Yasuteru; Kukita, Yutaka*; Nakamura, Hideo; Park, H. S.*; Anoda, Yoshinari
Proceedings of 8th International Conference on Nuclear Engineering (ICONE-8) (CD-ROM), p.12 - 0, 2000/00
no abstracts in English
Shibamoto, Yasuteru; Nakamura, Hideo; Anoda, Yoshinari; Kukita, Yutaka*
JAERI-Tech 99-042, 41 Pages, 1999/05
no abstracts in English
Moriyama, Kiyofumi; ; Maruyama, Yu; Kudo, Tamotsu; Sugimoto, Jun
JAERI-Data/Code 99-017, 34 Pages, 1999/03
JAERI-Data-Code-99-017.pdf:7.96MB
no abstracts in English
A.R.Antariksawan*; Moriyama, Kiyofumi; H.Park*; Maruyama, Yu; Y.Yang*; Sugimoto, Jun
JAERI-Review 98-012, 66 Pages, 1998/09
JAERI-Review-98-012.pdf:3.36MB
no abstracts in English
; Maruyama, Yu; Kudo, Tamotsu; Moriyama, Kiyofumi; Ito, Hideo; ; ; Sugimoto, Jun
JAERI-Tech 98-019, 105 Pages, 1998/06
no abstracts in English
Park, H.; Yamano, Norihiro; Maruyama, Yu; Moriyama, Kiyofumi; Yang, Y.; Sugimoto, Jun
Dai-35-Kai Nihon Dennetsu Shimpojiumu Koen Rombunshu, 3, p.803 - 804, 1998/00
no abstracts in English
Park, H.; ; Moriyama, Kiyofumi; Maruyama, Yu; Y.Yang*; Sugimoto, Jun
Proc. of 11th Int. Heat Transfer Conf. (Heat Transfer 1998), 6, p.69 - 74, 1998/00
no abstracts in English
H.S.Park*; ; Maruyama, Yu; Moriyama, Kiyofumi; Y.Yang*; Sugimoto, Jun
Proc. of 1998 ASME/JSME Joint Pressure Vessels and Piping Conf., 362, p.49 - 56, 1998/00
no abstracts in English
H.Park*; ; Maruyama, Yu; Moriyama, Kiyofumi; Y.Yang*; Sugimoto, Jun
Proc. of 6th Int. Conf. on Nucl. Eng. (ICONE-6) (CD-ROM), 12 Pages, 1998/00
no abstracts in English
H.Park*; ; Maruyama, Yu; Moriyama, Kiyofumi; Y.Yang*; Sugimoto, Jun
Proceedings of 1st Korea-Japan Symp. on Nuclear Thermal Hydraulics and Safety (NTHAS 98), 8 Pages, 1998/00
no abstracts in English
Nariai, Hideki*; Sugiyama, Kenichiro*; Kataoka, Isao*; Mishima, Kaichiro*; *; Monde, Masanori*; Sugimoto, Jun; ; Hidaka, Akihide; *; et al.
Nihon Genshiryoku Gakkai-Shi, 39(9), p.739 - 752, 1997/00
Times Cited Count：1 Percentile：10.53(Nuclear Science & Technology)no abstracts in English
