Development of reactor vessel thermal hydraulic evaluation method under natural circulation decay heat removal conditions in sodium-cooled fast reactor

Hamase, Erina; Imai, Yasutomo; Doda, Norihiro; Tanaka, Masaaki

doi:10.1299/jsmemecj.2020.s08111

Cited by 2 publications

(3 citation statements)

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“…It was known that the axial flow is dominant compared with the lateral flow in the wire-wrapped subassembly (Ohshima and Imai, 2006). And, the subchannel CFD model have been validated by comparing numerical results with experimental data for a subassembly in the high and low flow rate conditions (Hamase, et al, 2019(Hamase, et al, , 2020. Hence, it was recognized the γ in the radial advection term has little influence into the evaluation of thermal-hydraulics in the subassembly.…”

Section: Numerical Model Of Subassembliesmentioning

confidence: 99%

“…13(b). In the forward-flow condition, the subchannel CFD model including the mixing correlation have been validated by comparing numerical results with the subchannel thermal-hydraulics analysis code ASFRE and experimental data for a subassembly in the high and low flow rate conditions (Hamase, et al, 2019(Hamase, et al, , 2020. In future work, the subchannel CFD model will be validated for the experiment where the circulation flow in the subassembly occurs by the cooling effect of IWF.…”

Section: Thermal-hydraulics In Subassembliesmentioning

confidence: 99%

“…Therefore, this study constructed a multidimensional thermal-hydraulics analysis model in the RV using a computational fluid dynamics (CFD) code (RV-CFD model) incorporated with a low-resolution mesh arrangement in the subassembly (subchannel CFD model) (Hamase, et al, 2019(Hamase, et al, , 2020, and was intended to validate the RV-CFD model with subchannel CFD model for core-plenum interactions during the D-DHX operation under NC conditions by comparing two numerical simulations with sodium experiments conducted in the PLANDTL-1 (Nishimura, et al, 2000;Kamide, et al, 2000). First, to focus on the radial heat transfer, the D-DHX was not operated; therefore, the penetration flow of cold sodium into the core was negligible, and the temperature difference among subassemblies was made by assigning different power to flow ratios in the experiment.…”

Section: Introductionmentioning

confidence: 99%

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Core thermal-hydraulics analysis during dipped-type direct heat exchanger operation in natural circulation conditions

Hamase

Miyake

Imai

et al. 2022

Mechanical Engineering Journal

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A direct reactor auxiliary cooling system (DRACS) under natural circulation (NC) conditions with a dipped-type direct heat exchanger (D-DHX) in the upper plenum of a reactor vessel (RV) has been investigated for enhancing the safety of sodium-cooled fast reactors. Studies of the past have revealed that core-plenum interactions, which consists of penetration of the coolant from D-DHXs into the subassemblies and the narrow gap between them (IWF: inter-wrapper flow), and the heat transfer through a wrapper tube among subassemblies (radial heat transfer), occurred and increased core cooling performance during the DRACS operation. Therefore, a multidimensional thermal-hydraulics analysis model in the RV using a computational fluid dynamics (CFD) code (RV-CFD model) was developed to evaluate the core cooling performance. For the design study, the RV-CFD model must simulate reasonable calculation costs while maintaining accuracy. In this study, the subchannel analysis method using the CFD code for fuel subassemblies (subchannel CFD model) was applied to the RV-CFD model. In the subchannel CFD model, the porous media approach was used to consider local geometry in the fuel subassembly, and the effective heat conductivity coefficients in a diffusion term of the energy equation were set to fit the actual radial thermal diffusion between subchannels. Two numerical simulations were compared to the experimental data obtained from the sodium experimental apparatus PLANDTL-1. In the first case, the focus was only the radial heat transfer without the D-DHX operation. In another case with the D-DHX operation, the IWF noticeably occurred, and the focus was on the core-plenum thermal interaction. The calculated sodium temperature in the core correlated well with the experimental results. The RV-CFD with subchannel CFD model was validated for core-plenum interactions during the DRACS with the D-DHX operation under NC conditions.

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Section: Numerical Model Of Subassembliesmentioning

confidence: 99%

Section: Thermal-hydraulics In Subassembliesmentioning

confidence: 99%