Matsuba, Kenichi; Kamiyama, Kenji; Toyooka, Junichi; Tobita, Yoshiharu; Zuyev, V. A.*; Kolodeshnikov, A. A.*; Vassiliev, Y. S.*
Mechanical Engineering Journal (Internet), 3(3), p.15-00595_1 - 15-00595_8, 2016/06
To develop a method for evaluating the distance for fragmentation of molten core material discharged into sodium, the particle size distribution of alumina debris obtained in the FR tests was analyzed. The mass median diameters of solidified alumina particles were around 0.3 mm, which are comparable to particle sizes predicted by hydrodynamic instability theories such as Kelvin-Helmholtz instability. However, even though hydrodynamic instability theories predict that particle size decreases with an increase of Weber number, such the dependence of particle size on We was not observed in the FR tests. It can be interpreted that this tendency of measured mass median suggests that before hydrodynamic instabilities sufficiently grow to induce fragmentation, thermal phenomena such as local coolant vaporization and resultant vapor expansion accelerate fragmentation.
Kamiyama, Kenji; Konishi, Kensuke; Sato, Ikken; Toyooka, Junichi; Matsuba, Kenichi; Zuyev, V. A.*; Pakhnits, A. V.*; Vityuk, V. A.*; Vurim, A. D.*; Gaidaichuk, V. A.*; et al.
Journal of Nuclear Science and Technology, 51(9), p.1114 - 1124, 2014/09
Kamiyama, Kenji; Saito, Masaki*; Matsuba, Kenichi; Isozaki, Mikio; Sato, Ikken; Konishi, Kensuke; Zuyev, V. A.*; Kolodeshnikov, A. A.*; Vassiliev, Y. S.*
Journal of Nuclear Science and Technology, 50(6), p.629 - 644, 2013/06
In core disruptive accidents of sodium cooled fast reactors, fuel discharge from the core region reduces the possibility of severe re-criticality events. In-core coolant channels such as the control-rod guide tube and a concept of the FAIDUS (Fuel Assembly with Inner Duct Structure) provide effective fuel discharge paths if effects of sodium in these paths on molten fuel discharge are limited. Two series of experiments conducted in the present study showed that the discharge path can be entirely voided by the vaporization of a part of the coolant at the initial melt discharge phase, that this is followed by coolant vapor expansion, and that melt penetrates significantly into the voided channel. In conclusion, the effects of the sodium on fuel discharge are limited and therefore in-core coolant channels provide effective fuel discharge paths for reducing neutronic activity.
Kamiyama, Kenji; Konishi, Kensuke; Sato, Ikken; Toyooka, Junichi; Matsuba, Kenichi; Zuyev, V. A.*; Pakhnits, A. V.*; Vurim, A. D.*; Gaidaichuk, V. A.*; Kolodeshnikov, A. A.*; et al.
Proceedings of 8th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-8) (USB Flash Drive), 7 Pages, 2012/12
In order to eliminate energetics potential in the case of postulated core disruptive accidents (CDAs) of sodium-cooled fast reactors, introduction of a fuel subassembly with an inner duct structure has been considered. Recently, a design option which leads molten fuel to discharge upward is considered to minimize developmental efforts for the fuel subassembly fabrication. In this paper, a series of out-of-pile tests and one in-pile test were presented. The out-of-pile tests were conducted to investigate the effects of driving pressures on upward discharge, and the in-pile test was conducted to demonstrate a sequence of upward discharge behavior of molten-fuel. Based on these experimental results, it is concluded that the most of molten-fuel is expected to complete discharging upward before core melting progression, and thereby, introduction of the fuel subassembly with the upward discharge duct has the sufficient potential to eliminate energetics events.
Kamiyama, Kenji; Konishi, Kensuke; Sato, Ikken; Kubo, Shigenobu*; Kotake, Shoji*; Shimakawa, Yoshio*; Koyama, Kazuya*; Zuyev, V.*; Vassiliev, Y. S.*; Kolodeshnikov, A.*
no journal, ,
no abstracts in English
Konishi, Kensuke; Kubo, Shigenobu*; Koyama, Kazuya*; Kamiyama, Kenji; Toyooka, Junichi; Sato, Ikken; Kotake, Shoji*; Vurim, A. D.*; Zuyev, V.*; Pakhnits, A. V.*; et al.
no journal, ,
In the EAGLE program, several in-pile and out-of-pile tests have been conducted by August 2006, under a co-operation between JAEA and NNC/RK. The main objectives of these tests are; (1) to demonstrate effectiveness of special design concepts to eliminate the re-criticality issue in the course of CDAs of SFRs, and (2) to acquire basic information on early-phase relocation of molten-core materials toward cold regions surrounding the core, which would be applicable to various core design concepts. As the final step of this program, integral in-pile tests simulating realistic accident conditions were conducted. Geometry of the test apparatus adopted in these tests is corresponding to a typical special design concept equipped with a "discharge duct" within each fuel sub-assembly. In these tests, fuel-steel mixture pool was successfully realized and discharge of the pool materials through the duct was observed.
Kubo, Shigenobu; Tobita, Yoshiharu; Sato, Ikken; Kotake, Shoji*; Endo, Hiroshi*; Koyama, Kazuya*; Konishi, Kensuke; Kamiyama, Kenji; Matsuba, Kenichi; Toyooka, Junichi; et al.
no journal, ,
As the results of good collaboration between Kazakhstan and Japan in EAGLE-1and 2, it was shown that there exists a solution to the recriticality issue of SFR, which has been one of the major safety issues for more than a half century from the beginning of the SFR development. Experimental techniques and facilities have been developed for the SFR severe accident study. Since 2014, JAEA participates the ASTRID program in which severe accident study is one of important issues. The EAGLE-1 and 2 data will be also used as an essential part of the severe accident study for ASTRID. EAGLE-3 was just started from beginning of 2015. Points of experiments moved into the later phase of core damage process, i.e., material relocation and cooling after achieving neutronic shutdown. A number of out-of-pile tests and in-pile tests are planned in coming five years.