Study on the discharge behavior of molten-core through the control rod guide tube in the core disruptive accident of SFR

Kato, Shinya; Matsuba, Kenichi; Kamiyama, Kenji; Ganovichev, D. A.*; Baklanov, V. V.*

Proceedings of 2019 International Congress on Advances in Nuclear Power Plants (ICAPP 2019) (Internet), 9 Pages, 2019/05

In order to ensure In-Vessel Retention (IVR) of molten-core in Core Disruptive Accident (CDA), we are investigating the possibility of the molten-core discharge through the control rod guide tube (CRGT) to prevent energetics due to exceeding the prompt criticality. Internal structures of the CRGT, such as a sodium-flow regulator when the CRGT is connected to the high-pressure plenum, may disturb the discharge of molten-core from the core region. Based on above background, an experimental program to clarify characteristics of molten-core discharge through the CRGT has been commenced as one of subjects under a joint study with National Nuclear Center of the Republic of Kazakhstan (NNC-RK) named EAGLE-3 project. An experiment using molten-alumina as fuel simulant and sodium was conducted at the out-of-pile test facility owned by NNC-RK to investigate sodium cooling effect around the sodium flow regulator on its destruction. The experimental result represented that void development at the initiation of molten-alumina discharge eliminated liquid-phase sodium from the discharge path and this also eliminated sodium cooling effect around the sodium flow regulator. As a result, early destruction of the sodium flow regulator and massive discharge of molten alumina occurred in turn.

An Experimental study on the fragmentation and accompanying cooling behaviors of a simulated molten oxide fuel penetrating into a sodium pool

Matsuba, Kenichi; Kamiyama, Kenji; Toyoka, Junichi; Zuev, V. A.*; Kolodeshnikov, A. A.*

Proceedings of 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-17) (USB Flash Drive), 11 Pages, 2017/09

To clarify jet fragmentation and accompanying cooling behaviors of molten core materials discharged into sodium, results of the out-of-pile experiments with a simulant material (AlO) were analyzed. The results clarified that while AlO jets were entirely fragmented into smaller particles during their penetration to several tenths of a meter in depth of sodium, an additional significant distance was needed to cool down the particles to the degree that thermal loading on the steel structures could be neglected. Based on the results, it is concluded that in terms of the reduction of thermal load on the lower structures in the reactor vessels, the cooling distance after fragmentation should be treated.

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

Matsuba, Kenichi; Kamiyama, Kenji; Toyoka, 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

http://doi.org/10.1299/mej.15-00595

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.

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; Toyoka, 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

Retesting of Mo adsorption and Tc elution characteristics of molybdenum adsorbents for (n,) method; Joint experiment report on irradiation technology of RI production (STC No.2II) (Joint research)

Kimura, Akihiro; Izumo, Hironobu; Tsuchiya, Kunihiko; Hori, Naohiko; Ishihara, Masahiro; Bannykh, V.*; Gluschenko, N.*; Chakrova, Y.*; Chakrov, P.*

JAEA-Testing 2010-002, 20 Pages, 2010/08

JAEA-Testing-2010-002.pdf:2.92MB

JMTR has a plan to produce Mo, which is the parent nuclide of radiopharmaceutical Tc, by (n,) method. The cooperation experiments for Mo adsorption and Tc elution with the Poly-Zirconium Compound (PZC) and the Molybdate Zirconium Gel (Zr-gel) methods were carried out at Kazakhstan National Nuclear Energy Center (NNC) in October, 2009. The Mo adsorption capability was the same level as reference data, however the Tc elution capability with PZC was lower than reference data in this test. Therefore, re-experiments of Mo adsorption and Tc elution with both methods were carried out at NNC. As a result, the Mo adsorption and Tc elution capabilities were obtained as the same levels as reference data. Additionally, Tc solution was high purity by the elution method connected with alumina column.

Tritium generation in lithium ceramics LiTiO for fusion reactor blanket

Tazhibayeva, I. L.*; Kenzhin, E. A.*; Kulsartov, T. V.*; Kuykabayeva, A. A.*; Shestakov, V.*; Chikhray, E.*; Gizatulin, S.*; Maksimkin, O. P.*; Beckman, I. N.*; Kawamura, Hiroshi; et al.

Questions of Atomic Science and Technology, 2, p.3 - 11, 2008/00

Lithium titanate (LiTiO) was chosen as a tentative reference material from viewpoints of good tritium recovery at low temperatures and of low tritium inventory and chemical stability for the breeding blanket in fusion reactors. The results of the irradiation tests of LiTiO in the WWR-K of NNC-RK are described in this paper. 96at% Li-enriched LiTiO pebbles and disks were prepared as the irradiation specimens and these specimens were irradiated during 220 days (5350 hours) at the reactor power of 6 MWt. Tritium release was measured continuously during irradiation tests and tritium release properties were evaluated. The mechanics describing generation and release of tritium from the irradiated LiTiO were analyzed. There was estimated tritium loss due to recoil energy and binding of tritium in HTO, and there was calculated stationary tritium release due to diffusion under constant temperature and under thermal cycling.

Experimental study on molten core material relocation during core disruptive accidents in fast reactors

Toyoka, Junichi; Konishi, Kensuke; Kamiyama, Kenji; Tobita, Yoshiharu; Sato, Ikken; Kotake, Shoji*

no journal, , 

no abstracts in English

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 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.

Experimental study on fragmentation behavior of molten core material during core disruptive accident for sodium-cooled fast reactors; Discussion on the fragmentation mechanism

Matsuba, Kenichi; Kamiyama, Kenji; Tobita, Yoshiharu; Toyoka, Junichi; Zuev, V.*; Kolodeshnikov, A.*; Vasilyev, Y.*

no journal, , 

In order to obtain experimental knowledge on fragmentation behavior of molten core material discharged into the lower sodium plenum in the reactor vessel during core disruptive accidents of sodium cooled fast reactors, a series of fragmentation experiments have been carried out with a molten oxide. Based on the experimental results, dominant mechanisms for the fragmentation behavior was discussed.

Applicability assessment of empirical correlations to the prediction of the distance for fragmentation of molten core materials in sodium

Matsuba, Kenichi; Isozaki, Mikio; Toyoka, Junichi; Kamiyama, Kenji; Zuev, V.*; Kolodeshnikov, A.*

no journal, , 

In order to assess the fragmentation behavior of molten core material discharged into the lower sodium plenums during core disruptive accidents in sodium-cooled fast reactors, applicability of empirical correlations of the distance for fragmentation was investigated by comparing the values predicted using a correlation with the results obtained in the experiments where a simulated core material (molten alumina) was discharged into a sodium pool.