[1N05-09] Applications of Quantum Beam and Targets 1

[1N07] R&D on Mercury Target for Spallation Neutron Source to Improve the Durability under High Power Operation

(3) Experimental observation of bubble coalescence phenomenon and development of numerical prediction code

*Gen Ariyoshi¹, Kei Ito², Hiroyuki Kogawa¹, Masatoshi Futakawa¹ (1. JAEA, 2. Kyoto Univ.)

Keywords:Mercury spallation target, Pressure wave, Cavitation damage, Microbubble, Liquid-metal two-phase flow

Cavitation damage caused by pressure waves is one of the important issues which threaten the integrity of the mercury spallation target vessel in J-PARC. To mitigate the damage, technology using mercury-helium two-phase flow has been developed. Although effective bubble radius for absorption/attenuation of the waves is evaluated as less than 100 μm, actual bubble radius might be different from the evaluated one due to microbubble coalescence phenomena. Therefore, the purpose of present study is to clarify and predict the bubble radius distribution in the target. To achieve that, visualization of microbubble coalescence phenomena was performed by using air-water two-phase flow as a model flow. Obtained experimental results and numerical prediction code presently developed will be explained.