Numerical simulation method using a Cartesian grid for oxidation of core materials under steam-starved conditions

Yamashita, Susumu; Sato, Takumi; Nagae, Yuji; Kurata, Masaki; Yoshida, Hiroyuki

Journal of Nuclear Science and Technology, 17 Pages, 2023/00

https://doi.org/10.1080/00223131.2022.2162996

An Investigation of the microstructure and phase composition of the Zr bearing metallic debris in a bypass channel of a BWR fuel after the exothermic reaction in the CLADS-MADE-04 test

Pshenichnikov, A.; Kurata, Masaki; Nagae, Yuji

Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR2022) (Internet), 4 Pages, 2022/10

The CLADS-MADE-04 is the next test in the series aiming at understanding of the melt propagation behaviour in the lower core region. In this contribution, recent results of the post-test analysis including microstructure of metallic debris investigated by Electron Probe Micro Analyzer (EPMA) are discussed. During the test, melting of the control blade happened with sudden wave of strong heat release relatively slowly (several cm/min) spread from the hottest area downwards along the degrading control blade and channel box consuming the walls made of Zircaloy-4. A significant damage happened with the sample supporting plate as well. The investigation of microstructure of such metallic debris would allow understanding of a mechanism of enhanced local core degradation. The nature of strong heat release and possibility of spreading to the surrounding materials is to be confirmed after thorough phase identification by EPMA. The difference between Fe-B eutectic debris and Zr-Fe eutectic debris will be outlined. It is especially important for understanding of the lower core plate melt-through and a possibility of a Zr-Fe molten material progression into the lower plenum.

Raman investigation of the CLADS-MADE-02 test debris to confirm the mechanism of the volatile and non-volatile boron compounds formation

Pshenichnikov, A.; Nagae, Yuji; Kurata, Masaki

Proceedings of TopFuel 2021 (Internet), 12 Pages, 2021/10

Features of a BWR neutron absorber melt relocation in an oxidative environment during the CLADS-MADE-02 test

Pshenichnikov, A.; Nagae, Yuji; Kurata, Masaki

Proceedings of 28th International Conference on Nuclear Engineering (ICONE 28) (Internet), 7 Pages, 2021/08

https://doi.org/10.1115/ICONE28-65129

On the degradation progression of a BWR control blade under high-temperature steam-starved conditions

Pshenichnikov, A.; Nagae, Yuji; Kurata, Masaki

Mechanical Engineering Journal (Internet), 7(3), p.19-00503_1 - 19-00503_10, 2020/06

https://doi.org/10.1299/mej.19-00503

New research programme of JAEA/CLADS to reduce the knowledge gaps revealed after an accident at Fukushima-1; Introduction of boiling water reactor mock-up assembly degradation test programme

Pshenichnikov, A.; Kurata, Masaki; Bottomley, D.; Sato, Ikken; Nagae, Yuji; Yamazaki, Saishun

Journal of Nuclear Science and Technology, 57(4), p.370 - 379, 2020/04

https://doi.org/10.1080/00223131.2019.1691070

Oxidation kinetics of silicon carbide in steam at temperature range of 1400 to 1800C studied by laser heating

Pham, V. H.; Nagae, Yuji; Kurata, Masaki; Bottomley, D.; Furumoto, Kenichiro*

Journal of Nuclear Materials, 529, p.151939_1 - 151939_8, 2020/02

AA2019-0197.pdf:1.61MB

https://doi.org/10.1016/j.jnucmat.2019.151939

Fundamental study on segregation behavior in U-Zr-Fe-O system during solidification process

Sudo, Ayako; Mizusako, Fumiki*; Hoshino, Kuniyoshi*; Sato, Takumi; Nagae, Yuji; Kurata, Masaki

Nihon Genshiryoku Gakkai Wabun Rombunshi, 18(3), p.111 - 118, 2019/08

https://doi.org/10.3327/taesj.J18.029

Cooling rate of molten core materials during solidification significantly affects the segregation of major constituents of fuel debris. To understand general tendency of the segregation, liquefaction/solidification tests of simulated corium (UO, ZrO, FeO, BC and sim-FP oxides) were performed. Simulated corium was heated up to 2600C under Ar atmosphere and then cooled down with two different cooling processes; furnace cooling (average cooling rate is approximately 744C/min) and slow cooling (cooling rate in 2600C2300C is 5C/min and in 2300C1120C is approximately 788C/min). Element analysis detected three oxide phases with different composition and one metal phase in both solidified samples. Solubility of FeO in these oxide phases was mostly fixed to be 125at% in both samples, which is in reasonable accordance with the value estimated from UO-ZrO-FeO phase diagrams. However, a significant grain-growth of one oxide phase, rich in Zr-oxide, was detected only in the slowly cooled sample. The composition of this particular oxide phase is comparable to the initial average composition. The condensation is considered to be caused by the connection of remaining liquid agglomerates during slow solidification.

Features of a control blade degradation observed during severe accidents in boiling water reactors

Pshenichnikov, A.; Yamazaki, Saishun; Bottomley, D.; Nagae, Yuji; Kurata, Masaki

Journal of Nuclear Science and Technology, 56(5), p.440 - 453, 2019/05

https://doi.org/10.1080/00223131.2019.1592724

The Behaviour of materials in case of solidified absorber melt - oxidized BWR channel box interaction revealed after CLADS-MADE-01 test

Pshenichnikov, A.; Kurata, Masaki; Nagae, Yuji; Yamazaki, Saishun

Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR 2019) (Internet), 4 Pages, 2019/05