[1G13-18] Thermal Hydraulics in Fast Reactor

[1G13] Study on coolant behavior in damaged core of sodium-cooled fast reactor

Evaluation of interfacial drag term for high accuracy pressure drop prediction

*Tomohiro Mizuno¹, Naoya Odaira¹, Daisuke Ito¹, Kei Ito¹, Yasushi Saito¹, Yuya Imaizumi², Kenichi Matsuba², Kenji Kamiyama² (1. Kyoto Univ., 2. JAEA)

Keywords:debris bed, packed bed of spheres, sodium-cooled fast reactor, air-water two-phase flow, interfacial drag

In a severe accident of sodium-cooled fast reactor, ensuring stable cooling and achievement of in-vessel retention of the damaged core materials are important. Two-phase flow may occur due to sodium boiling within the debris bed. In our research group, we observed two-phase flow patterns in the quasi-two-dimensional packed bed system. Our observation revealed the flow patterns in a packed bed system differed from existing flow pattern maps. Interfacial drag is known to affect pressure drop evaluation, but interface drag terms for each flow pattern were scarcely considered. Therefore, we evaluated the influence of the interface drag on pressure drop evaluation for each flow pattern. Also, we examined appropriate interface drag models for the high accuracy pressure drop prediction.