CFD applications to pressurized thermal shock-related phenomena (Contract research, Translated document)

Okagaki, Yuria; Hibiki, Takashi*; Shibamoto, Yasuteru

JAEA-Review 2024-047, 58 Pages, 2025/02

JAEA-Review-2024-047.pdf:2.22MB

In PWR accident scenarios, the injection of water from the ECCS (ECC injection) might result in thermal stratification in the case of the insufficient mixing of cold and hot water and induce a PTS, affecting the RPV integrity. Therefore, PTS is a vital research issue in reactor safety, and its analysis is essential for evaluating the integrity of RPVs, which determines the reactor life. The PTS analysis comprises a coupled analysis between thermal-hydraulic and structural analysis. Especially in the thermal-hydraulic approach, reliable CFD simulations should play a vital role in the future because predicting the temperature gradient of the RPV wall requires data on the transient temperature distribution of the DC. This study reviewed from the viewpoint of the turbulence models most affecting PTS analysis based on papers published since 2010 on single- and two-phase flow CFD simulation for the experiment on PTS performed in the ROCOM, Transient TOPFLOW, UPTF, and LSTF.

Numerical simulation of bubble hydrodynamics for pool scrubbing

Okagaki, Yuria; Shibamoto, Yasuteru; Wada, Yuki; Abe, Satoshi; Hibiki, Takashi*

Journal of Nuclear Science and Technology, 60(8), p.955 - 968, 2023/08

https://doi.org/10.1080/00223131.2022.2161656

A Comparative CFD exercise on bubble hydrodynamics using Euler-Euler and interface tracking approaches

Dehbi, A.*; Cheng, X.*; Liao, Y.*; Okagaki, Yuria; Pellegrini, M.*

Proceedings of 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19) (Internet), 15 Pages, 2022/03

A Numerical investigation on the heat transfer and turbulence production characteristics induced by a swirl spacer in a single-tube geometry under single-phase flow condition

Abe, Satoshi; Okagaki, Yuria; Satou, Akira; Shibamoto, Yasuteru

Annals of Nuclear Energy, 159, p.108321_1 - 108321_12, 2021/09

https://doi.org/10.1016/j.anucene.2021.108321

LES-WALE simulation on two liquid mixing in the horizontal legs and downcomer; The Open-test condition in the TAMU-CFD benchmark (IBE-5)

Abe, Satoshi; Okagaki, Yuria; Ishigaki, Masahiro; Shibamoto, Yasuteru

Proceedings of OECD/NEA Workshop on Virtual CFD4NRS-8; Computational Fluid Dynamics for Nuclear Reactor Safety (Internet), 11 Pages, 2020/11

Experimental investigation of decontamination factor dependence on aerosol concentration in pool scrubbing

Sun, Haomin; Shibamoto, Yasuteru; Okagaki, Yuria; Yonomoto, Taisuke

Science and Technology of Nuclear Installations, 2019, p.1743982_1 - 1743982_15, 2019/06

https://doi.org/10.1155/2019/1743982

Heat conduction analyses on rewetting front propagation during transients beyond anticipated operational occurrences for BWRs

Yonomoto, Taisuke; Shibamoto, Yasuteru; Satou, Akira; Okagaki, Yuria

Journal of Nuclear Science and Technology, 53(9), p.1342 - 1352, 2016/09

AA2015-0497.pdf:1.05MB

https://doi.org/10.1080/00223131.2015.1108882

Our previous study investigated the rewetting behavior of dryout fuel surface during transients beyond anticipated operational occurrences (AOOs) for BWRs, which indicated the rewetting velocity was significantly affected by the precursory cooling defined as cooling immediately before rewetting. The present study further investigated the previous experiments by conducting additional experimental and numerical heat conduction analyses to characterize the precursory cooling. For the characterization, the precursory cooling was firstly defined quantitatively based on evaluated heat transfer rates; the rewetting velocity was investigated as a function of the cladding temperature immediately before the onset of the precursory cooling. The results indicated that the propagation velocity appeared to be limited by the maximum heat transfer rate near the rewetting front. This limitation was consistent with results of the heat conduction analysis.

Thermal hydraulic safety research at JAEA after the Fukushima Dai-ichi Nuclear Power Station accident

Yonomoto, Taisuke; Shibamoto, Yasuteru; Takeda, Takeshi; Satou, Akira; Ishigaki, Masahiro; Abe, Satoshi; Okagaki, Yuria; Sun, Haomin; Tochio, Daisuke

Proceedings of 16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-16) (USB Flash Drive), p.5341 - 5352, 2015/08

Safe storage of zeolite adsorbents used for treatment of accident-generated water at Fukushima Daiichi Power Station

Yamagishi, Isao; Nagaishi, Ryuji; Terada, Atsuhiko; Kamiji, Yu; Kato, Chiaki; Morita, Keisuke; Nishihara, Kenji; Tsubata, Yasuhiro; Ji, W.*; Fukushima, Hisashi*; et al.

IAEA-CN-211 (Internet), 5 Pages, 2013/01

http://www-pub.iaea.org/iaeameetings/IEM4/29Jan/Yamagishi.pdf

Since the accident at Fukushima Daiichi Nuclear Power Station, a large amount of radioactive contaminated water has been generated to cool damaged reactor cores. Adsorption of cesium with zeolite-like media was employed for treatment of this contaminated saline water. As spent zeolite media are highly radioactive, their safe storage is a pressing issue. Japan Atomic Energy Agency has extensively conducted R&D on the management of secondary wastes produced by the operation of the treatment system. Subjects on the safe storage of spent zeolites include the analysis of their characteristics and the evaluation of effectiveness of the present safety measures in consideration of decay heat emission and hydrogen generation by water radiolysis as well as durability of vessels exposed to saline. Preliminary results obtained are described in the present paper.

Numerical analysis of turbulent flow with heat transfer in a square duct with 45 degree ribs

Okagaki, Yuria*; Sugiyama, Hitoshi*; Kato, Naoto*; Terada, Atsuhiko; Hino, Ryutaro

Proceedings of 19th International Conference on Nuclear Engineering (ICONE-19) (CD-ROM), 8 Pages, 2011/10

Turbulent flow and heat transfer characteristics in a square duct of 100 mm height with 45 degree square ribs of 10 mm height was analyzed numerically by using algebraic Reynolds stress model including the fixed turbulent Prandtl number and algebraic turbulent heat flux models. In this research, analytical results were compared with the experimental and predicted data reported by Bonhoff et al, which were measured and analyzed turbulent flow fields at Reynolds number 50000 based on bulk velocity and duct height by means of a PIV system and a Reynolds stress model. As a result of this study, it was verified that the presented method was able to predict turbulent flow in duct with ribs through the comparison of calculated results with the experimental data.