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Journal Articles

Experimental discussion on fragmentation mechanism of molten oxide discharged into a sodium pool

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.

Journal Articles

An Experimental study on heat transfer from a mixture of solid-fuel and liquid-steel during core disruptive accidents in Sodium-Cooled Fast Reactors

Kamiyama, Kenji; Konishi, Kensuke; Sato, Ikken; Toyooka, Junichi; Matsuba, Kenichi; Suzuki, Toru; Tobita, Yoshiharu; Pakhnits, A. V.*; Vityuk, V. A.*; Vurim, A. D.*; et al.

Proceedings of 10th International Topical Meeting on Nuclear Thermal Hydraulics, Operation and Safety (NUTHOS-10) (USB Flash Drive), 8 Pages, 2014/12

Journal Articles

Experimental studies on the upward fuel discharge for elimination of severe recriticality during core-disruptive accidents in sodium-cooled fast reactors

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

AA2013-0469.pdf:1.18MB

 Times Cited Count:10 Percentile:63.4(Nuclear Science & Technology)

Journal Articles

Experimental study on fuel-discharge behavior through in-core coolant channels

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

 Times Cited Count:18 Percentile:81.6(Nuclear Science & Technology)

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.

Journal Articles

Experimental studies on upward fuel discharge during core disruptive accident in sodium-cooled fast reactors

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.

Journal Articles

Safety strategy of JSFR eliminating severe recriticality events and establishing in-vessel retention in the core disruptive accident

Sato, Ikken; Tobita, Yoshiharu; Konishi, Kensuke; Kamiyama, Kenji; Toyooka, Junichi; Nakai, Ryodai; Kubo, Shigenobu*; Kotake, Shoji*; Koyama, Kazuya*; Vassiliev, Y. S.*; et al.

Journal of Nuclear Science and Technology, 48(4), p.556 - 566, 2011/03

In the JSFR design, elimination of severe recriticality events in the Core Disruptive Accident (CDA) is intended as an effective measure to assure retention of the core materials within the reactor vessel. The design strategy is to control the potential of excessive void reactivity insertion in the Initiating Phase selecting appropriate design parameters such as maximum void reactivity on one hand, and to exclude core-wide molten-fuel-pool formation, which has been the main issue of CDA, with introduction of Inner Duct on the other hand. The effectiveness of these measures are reviewed based on existing experimental data and evaluations performed with validated analysis tools. It is judged that the present JSFR design can exlude severe power burst events.

Journal Articles

The Result of a wall failure in-pile experiment under the EAGLE project

Konishi, Kensuke; Toyooka, Junichi; Kamiyama, Kenji; Sato, Ikken; Kubo, Shigenobu*; Kotake, Shoji*; Koyama, Kazuya*; Vurim, A. D.*; Gaidaichuk, V. A.*; Pakhnits, A. V.*; et al.

Nuclear Engineering and Design, 237(22), p.2165 - 2174, 2007/11

 Times Cited Count:41 Percentile:92.71(Nuclear Science & Technology)

The WF (Wall Failure) test of the EAGLE program, in which $$sim$$2kg of uranium dioxide fuel-pins were melted by nuclear heating, was successfully conducted in the IGR of NNC/Kazakhstan. In this test, a 3mm-thick stainless steel (SS) wall structure was placed between fuel pins and a 10mm-thick sodium-filled channel (sodium gap). During the transient, fuel pins were heated, which led to the formation of a fuel-steel mixture pool. Under the transient nuclear heating condition, the SS wall was strongly heated by the molten pool, leading to wall failure. The time needed for fuel penetration into the sodium-filled gap was very short (less than 1 second after the pool formation). The result suggests that molten core materials formed in hypothetical LMFBR core disruptive accidents have a certain potential to destroy SS-wall boundaries early in the accident phase, thereby providing fuel escape paths from the core region. The early establishment of such fuel escape paths is regarded as a favorable characteristic in eliminating the possibility of severe re-criticality events.

Journal Articles

The Eagle project to eliminate the recriticality issue of fast reactors; Progress and results of in-pile tests

Konishi, Kensuke; Kubo, Shigenobu*; Sato, Ikken; Koyama, Kazuya*; Toyooka, Junichi; Kamiyama, Kenji; Kotake, Shoji*; Vurim, A. D.*; Gaidaichuk, V. A.*; Pakhnits, A. V.*; et al.

Proceedings of 5th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-5), p.465 - 471, 2006/11

no abstracts in English

Journal Articles

The Result of medium scale in-pile experiment conducted under the EAGLE-project

Konishi, Kensuke; Toyooka, Junichi; Kamiyama, Kenji; Sato, Ikken; Kubo, Shigenobu*; Kotake, Shoji*; Koyama, Kazuya*; Vurim, A. D.*; Gaidaichuk, V. A.*; Pakhnits, A. V.*; et al.

Proceedings of Technical Meeting on Severe Accident and Accident Management (CD-ROM), 16 Pages, 2006/03

no abstracts in English

Oral presentation

EAGLE project; Experimental study on elimination of the Re-criticality issue during CDAs, 12; The Prompt result of in-pile large scale dry test

Konishi, Kensuke; Toyooka, Junichi; Kamiyama, Kenji; Sato, Ikken; Kubo, Shigenobu*; Kotake, Shoji*; Koyama, Kazuya*; Vurim, A. D.*; Pakhnits, A. V.*; Gaidaichuk, V. A.*; et al.

no journal, , 

no abstracts in English

Oral presentation

EAGLE project; Experimental study on elimination of the Re-criticality issue during CDAs, 13; Results of the sodium test in the out-of-pile program

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

Oral presentation

EAGLE project; Experimental study on elimination of the Re-criticality issue during CDAs, 14; The Result and interpretation of in-pile middle scale test

Toyooka, Junichi; Konishi, Kensuke; Kamiyama, Kenji; Sato, Ikken; Kubo, Shigenobu*; Kotake, Shoji*; Koyama, Kazuya*; Vurim, A. D.*; Pakhnits, A. V.*; Gaidaichuk, V. A.*; et al.

no journal, , 

no abstracts in English

Oral presentation

EAGLE project: Experimental study on elimination of re-criticality issue during CDAs, 15; The Result of the first in-pile integral test

Konishi, Kensuke; Toyooka, Junichi; Kamiyama, Kenji; Sato, Ikken; Kubo, Shigenobu*; Kotake, Shoji*; Koyama, Kazuya*; Vurim, A. D.*; Gaidaichuk, V. A.*; Pakhnits, A. V.*; et al.

no journal, , 

no abstracts in English

Oral presentation

EAGLE-project: Experimental study on elimination of re-criticality issue during CDAs, 18; The Result of the second in-pile integral test

Konishi, Kensuke; Toyooka, Junichi; Kamiyama, Kenji; Sato, Ikken; Kubo, Shigenobu*; Kotake, Shoji*; Koyama, Kazuya*; Vurim, A. D.*; Pakhnits, A. V.*; Gaidaichuk, V. A.*; et al.

no journal, , 

The EAGLE experimental program is dedicated to show experimental evidences supporting a safety logic eliminating the recriticality issue in the core disruptive accidents (CDAs) of sodium-cooled fast breeder reactors. In order to confirm an inherent nature of early fuel escape from the core region, both in-pile (using IGR) and out-of-pile experiments have been performed in the program. This presentation shows the preliminary interpretation of the second integral experiment, in which fuel discharge through a duct-type escape path (initially filled with sodium) was investigated using about 8kg of molten fuel. Energy insertion in this second experiment was smaller than that in the first experiment. The duct-wall failure timing was a little delayed compared with that in the first experiment, and the fuel discharged through the duct intermittently.

Oral presentation

EAGLE-project: Experimental study on elimination of re-criticality issue during CDAs, 19; Identification of fuel movement using neutron detectors

Koyama, Kazuya*; Saruyama, Ichiro*; Konishi, Kensuke; Toyooka, Junichi; Kamiyama, Kenji; Sato, Ikken; Kubo, Shigenobu*; Kotake, Shoji*; Vurim, A. D.*; Pakhnits, A. V.*; et al.

no journal, , 

The EAGLE experimental program is dedicated to show experimental evidences supporting a safety logic eliminating the recriticality issue in the core disruptive accidents (CDAs) of sodium-cooled fast breeder reactors. Two kinds of neutron detectors (one was placed in the test section and another was placed around IGR driver core for power monitoring use) were analyzed to get prospect that the data include information of molten-fuel motion in the in-pile test.

Oral presentation

Overview on the EAGLE experimental program aiming at resolution of the re-criticality issue for the fast reactors

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.

Oral presentation

EAGLE project; Experimental study on elimination of the re-criticality issue during CDAs, 20; Evaluation of molten fuel-pool heat transfer in the ID1 test

Toyooka, Junichi; Konishi, Kensuke; Kamiyama, Kenji; Sato, Ikken; Kubo, Shigenobu*; Kotake, Shoji*; Koyama, Kazuya*; Vurim, A. D.*; Pakhnits, A. V.*; Gaidaichuk, V. A.*; et al.

no journal, , 

no abstracts in English

Oral presentation

Collaboration of JAEA and NNC for Kazakhstan project on high-temperature gas-cooled reactor

Nakatsuka, Toru; Levin, A. G.*; Ueta, Shohei; Gizatulin, S.*; Tachibana, Yukio; Kolodeshnikov, A.*; Sakaba, Nariaki; Chakrov, P.*; Kunitomi, Kazuhiko; Vassiliev, Y. S.*; et al.

no journal, , 

The small-sized high-temperature gas-cooled reactors (HTGRs) with an electric power rating of less than 300 MWe can greatly facilitate decentralized energy supply, and create new industries and stimulate economical development in cities and localities as well as in those remote regions to which power transmission grids are undeveloped in developing countries such as Kazakhstan. In 2007, Japan Atomic Energy Agency (JAEA) and National Nuclear Center of Kazakhstan (NNC) have started to collaborate in nuclear energy research and development for early realization of deployment of the HTGR in Kazakhstan, and to support for the Kazakhstan HTGR (KHTR) Project by utilizing the technologies developed under the High Temperature Engineering Test Reactor (HTTR) Project. In 2010, JAEA started a conceptual design of KHTR steam turbine system with thermal power of 50 MW and the maximum coolant temperature at reactor outlet of 750 $$^{circ}$$C for earlier development of HTGRs with support of Japan parties, which consists of Japanese industrial companies, etc. in order to support NNC for preparation of the feasibility study of KHTR.

Oral presentation

Experimental studies on discharge of molten-core materials during core disruptive accidents for sodium-cooled fast reactors; Results of post-test investigations on the in-pile test devices

Kamiyama, Kenji; Konishi, Kensuke; Sato, Ikken; Matsuba, Kenichi; Tobita, Yoshiharu; Toyooka, Junichi; Pakhnits, A. V.*; Vityuk, V.*; Kukushkin, I.*; Vurim, A. D.*; et al.

no journal, , 

no abstracts in English

Oral presentation

Main outcomes and future plan of the EAGLE project

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.

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