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Kaji, Yoshiyuki; Nemoto, Yoshiyuki; Nagatake, Taku; Yoshida, Hiroyuki; Tojo, Masayuki*; Goto, Daisuke*; Nishimura, Satoshi*; Suzuki, Hiroaki*; Yamato, Masaaki*; Watanabe, Satoshi*
Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 8 Pages, 2019/05
In this research program, cladding oxidation model in SFP accident condition, and numerical simulation method to evaluate capability of spray cooling system which was deployed for spent fuel cooling during SFP accident, have been developed. These were introduced into the severe accident codes such as MAAP and SAMPSON, and SFP accident analyses were conducted. Analyses using Computational Fluid Dynamics (CFD) code were conducted as well for the comparison with SA code analyses and investigation of detail in the SFP accident. In addition, three-dimensional criticality analysis method was developed as well, and safer loading pattern of spent fuels in pool was investigated.
Nishimura, Satoshi*; Satake, Masaaki*; Nishi, Yoshihisa*; Nemoto, Yoshiyuki; Kaji, Yoshiyuki
Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 8 Pages, 2019/05
In this study, accident progression analyses in the SFP were performed to investigate cooling effects of the SFP spray and an alternate water injection in the loss-of-pool water accident with MAAP ver. 5.05 beta. Fuel cladding oxidation model which was created by JAEA based on their experimental data was selected and applied in the present calculations. In case of an assessment of SFP spray effects, decay heat, spray fraction going into the fuel assembly, spray droplet diameter, spray start time were selected as analytical parameters. When the SFP spray of 12.5 kg/s (200 GPM) starts 4 hours after the onset of the accident against the spent fuels with 4 months cooling and if the spray fraction going into the fuel assembly is greater than 30%, the maximum cladding temperature can be maintained under 727
C (1000 K), resulting in avoiding the cladding failure.
Nishimura, Satoshi*; Satake, Masaaki*; Nishi, Yoshihisa*; Kaji, Yoshiyuki; Nemoto, Yoshiyuki
Proceedings of 11th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-11) (Internet), 3 Pages, 2018/11
After the accident of Fukushima-unit 1 Nuclear Power Plant, Japanese utilities are newly requested by regulatory body to take prompt measures to enhance the safety of spent fuel pool. The most important objective of this new Japanese standards of regulation is keeping a water level in a Spent Fuel Pool (SFP) under any situations in order to prevent fuel failures due to increase of fuel temperature and to avoid the occurrence of re-criticality accidents. The utilities are considered to install several kinds of safety measures for SFP. For example, a spray injection and an alternate water injection to keep pool water level, and a spent fuel layout, such as 1 by 4, 1 by 8, checkerboard to enhance cooling of the spent fuel in SFP. The objective of the present study is to investigate the effect of spent fuel layout on SFP cooling with MAAP5.04.
Ohshima, Hiroyuki; Sakai, Takaaki; Kamide, Hideki; Kimura, Nobuyuki; Ezure, Toshiki; Uchibori, Akihiro; Ito, Kei; Kunugi, Tomoaki*; Okamoto, Koji*; Tanaka, Nobuatsu*; et al.
JAEA-Research 2008-049, 44 Pages, 2008/06
JAEA-Research-2008-049.pdf:42.3MB
Japan Atomic Energy Agency has conducted a conceptional design study of a sodium-cooled fast reactor in a frame work of the FBR feasibility study. The plant system concept for a commercial step is intended to minimize a vessel diameter to achieve an economical competitiveness. Therefore, the coolant in the vessel has relatively higher velocity and gas entrainment (GE) prevention from a liquid surface in the reactor vessel becomes one of important issues for the thermal-hydraulic design. In order to establish a design criteria for the GE prevention, the GE from vortex dimples at the liquid surface was investigated by a working group. The 1st proposal of "Design Guideline for Gas Entrainment Prevention Using CFD Method" was established based on the knowledge gained from the working group activities. This report introduces each study in the working group to clarify the basis of the design guideline.
Tomita, Yutaka; Morihira, Masayuki; Tamaki, Yoshihisa*; Nishimura, Kazuhisa*; Shoji, Shuichi*; Kihara, Yoshiyuki; Kase, Takeshi; Koizumi, Tsutomu
JAEA-Research 2006-088, 95 Pages, 2007/01
JAEA-Research-2006-088.pdf:23.02MB
JAEA has developed sphere-pac fuels in the feasibility study on commercialized FBR cycle systems as one of the candidates for low decontamination TRU fuels. Optimization of the fabrication condition for coarse spheres, development of an improved external gelation process, and examination of peculiar problems for the low decontamination fuel were carried out in Phase II. The results are shown as follows. (1) Fabrication condition of coarse spheres was optimized. (2) Feasibility of the improved external gelation process was confirmed. (3) Rare earth elements did not bring any problem for the characteristic of spheres and fabrication condition. (4) Radiation resistant data of the feed solution was acquired. Results of tests show the feasibility of the external gelation process for the low decontamination TRU fuel microsphere fabrication.
Nishimura, Kazuaki; Kato, Yoshiyuki; Kimura, Yuichi; Yoshimoto, Katsunobu; Komatsuzaki, Mai*; Kawasaki, Satoshi*
no journal, ,
no abstracts in English
MnSi/Ge(111) heteroepitaxial interfaces; Mn-concentration dependenceMaeda, Yoshihito; Nishimura, Kentaro*; Nagasawa, Yoshiyuki*; Narumi, Kazumasa; Sakai, Seiji
no journal, ,
no abstracts in English
-FeSi nanocrystalsNishimura, Kentaro*; Nagasawa, Yoshiyuki*; Maeda, Yoshihito*; Narumi, Kazumasa
no journal, ,
no abstracts in English
-FeSi nanocrystals by phase transition and enhancement of light emission propertyNishimura, Kentaro*; Nakajima, Takahito*; Nagasawa, Yoshiyuki*; Narumi, Kazumasa; Maeda, Yoshihito*
no journal, ,
Yoshitsugu, Yuichi; Tsujinaka, Hideyuki; Goto, Hirohito; Fujita, Masato; Nishimura, Yoshiyuki; Okui, Masahiro; Ito, Kimio; Ono, Takayuki
no journal, ,
At Ningyo-toge Environmental Engineering Center, Various actions are considered to be it for nuclear fuel plant decommissioning and to take a step. It is excepted that a large quantity of waste is occurred by equipments and buildings decommissioning. In our center, it is introduced a system of "Non radioactive Waste" to reduce quantity of radio waste. I introduce our system.
Kaji, Yoshiyuki; Nemoto, Yoshiyuki; Takase, Kazuyuki; Tojo, Masayuki*; Goto, Daisuke*; Iwata, Yutaka*; Otake, Yukihiko*; Nishimura, Satoshi*; Suzuki, Hiroaki*
no journal, ,
We will make quantitatively clear the phenomenon of fuel air oxidation mechanism, fuel failure mechanism after loss of coolant and criticality risks during and after sever accidents of Spent Fuel Pool(SFP) and clarify the quantitative effects of enhancements of SFP safety such as Spray and fuel loading patterns. We will report the whole plan in this presentation.
Nishimura, Satoshi*; Satake, Masaaki*; Soga, Shota*; Nishi, Yoshihisa*; Kaji, Yoshiyuki; Nemoto, Yoshiyuki
no journal, ,
We conducted the transient analysis for the phenomenon of loss of coolant in Spent Fuel Pool by Severe Accident code MAAP version 5.03 and evaluated quantitatively the influence of initial water level and decay heat on failure time and hydrogen generation of fuel cladding.
Wakai, Eiichi; Kondo, Hiroo; Kanemura, Takuji; Hirakawa, Yasushi; Furukawa, Tomohiro; Kikuchi, Takayuki; Ito, Yuzuru*; Hoashi, Eiji*; Yoshihashi, Sachiko*; Horiike, Hiroshi*; et al.
no journal, ,
no abstracts in English
Nishimura, Satoshi*; Satake, Masaaki*; Soga, Shota*; Nishi, Yoshihisa*; Kaji, Yoshiyuki; Nemoto, Yoshiyuki
no journal, ,
Using the severe accident code MAAP5.03, simulation of the loss of cooling function accident in spent fuel pool was conducted and cooling performance of the emergency cooling systems such as spray or water inlet was evaluated.
Nishimura, Satoshi*; Satake, Masaaki*; Nishi, Yoshihisa*; Kaji, Yoshiyuki; Nemoto, Yoshiyuki
no journal, ,
Oxidation models in dry air, in steam, and in mixture of air and steam, were previously proposed by JAEA. These oxidation models were introduced in the severe accident code MAAP, and applied for spent fuel pool accident analyses. The comparison of the analytical results with different oxidation model were conducted in this study.
Nishimura, Satoshi*; Satake, Masaaki*; Nishi, Yoshihisa*; Kaji, Yoshiyuki; Nemoto, Yoshiyuki; Nagatake, Taku
no journal, ,
In order to validate a spray cooling model for spent fuel pool (SFP) in the severe accident code "MAAP", benchmark analysis of SFP spray cooling tests was conducted with MAAP ver. 5.04. In a current spray cooling model in MAAP code, spray water entered into a fuel assembly flows down uniformly on the surface of fuel pins and fuel racks in the form of liquid film and cools the fuel pin from its top to the bottom. As a result, the current MAAP model causes effective cooling and leads to the tendency of overestimation of spray cooling rate comparing to the measured data.
Kaji, Yoshiyuki; Nemoto, Yoshiyuki; Nagatake, Taku; Yoshida, Hiroyuki; Tojo, Masayuki*; Goto, Daisuke*; Nishimura, Satoshi*; Suzuki, Hiroaki*; Yamato, Masaaki*
no journal, ,
The objectives of this study is to enhance the analytical method and safety of spent fuel pool under severe accident conditions. In this presentation, we explain about general view of results of this project.
Nishimura, Satoshi*; Satake, Masaaki*; Nishi, Yoshihisa*; Kaji, Yoshiyuki; Nemoto, Yoshiyuki
no journal, ,
After the accident in Fukushima-Daiichi Nuclear Power Plants in 2011, deployment of spray and substitutional water inlet systems for cooling the spent fuels are recommended as safety measures against spent fuel pool (SFP) accident. In this work, analyses on an hypothetical accident which occurred by simultaneous lost of cooling ability and leaking of cooling water in SFP were conducted by using the severe accident code MAAP. For the counter measure optimization, water inlet condition to avoid cladding rupture was investigated.
Habe, Hiroshi*; Inaba, Tomohiro*; Aoyagi, Tomo*; Aizawa, Hidenobu*; Sato, Yuya*; Hori, Tomoyuki*; Yamaji, Keiko*; Ohara, Yoshiyuki; Fukuyama, Kenjin; Cai, H.*; et al.
no journal, ,
no abstracts in English
Kanzaki, Norie; Minakawa, Ryuhei; Hikinuma, Yuichi; Sakoda, Akihiro; Nishimura, Yoshiyuki
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no abstracts in English
