Abstract
To perform basic Research and Development for future Accelerator-driven Systems (ADSs), Japan Proton Accelerator Research Complex (J-PARC) will construct an ADS target test facility. A Lead–Bismuth Eutectic (LBE) spallation target will be installed in the target test facility and bombarded by pulsed proton beams (250 kW, 400 MeV, 25 Hz, and 0.5 ms pulse duration). To realize the LBE spallation target, cavitation damage due to pressure changes in the liquid metal should be determined, preliminarily, because such damage is considered to be very critical, from the viewpoint of target safety and lifetime. In this study, cavitation damage due to pressure waves caused by pulsed proton beam injection and turbulent liquid metal flow, were studied, numerically, from the viewpoint of single cavitation bubble dynamics. Specifically, the threshold of cavitation and effects of flow speed fluctuation on cavitation bubble dynamics, in an orifice structure, were investigated in the present work. The results showed that the LBE spallation target did not undergo cavitation damage, under normal nominal operation conditions, mainly because of the long pulse duration of the pulsed proton beam and the low liquid metal flow velocity. Nevertheless, the possibility of cavitation damage in the orifice structure, under certain extreme transient LBE flow conditions, cannot be neglected.
Highlights
Heavy Liquid Metals (HLM) are usually employed as spallation materials and coolants in spallation targets, which are key components of neutron sources and Accelerator-Driven Systems (ADSs) [1,2]
By means of a numerical simulation, we investigated the possibility of occurrence of cavitation damage to the Lead–Bismuth Eutectic (LBE) spallation target, due to pressure waves and turbulent
It was noticed that the incubation period of the cavitation damage extended to approximately 109 pulses of proton beam injections, and there was hardly any cavitation damage on the test specimens, when the MIMTM power was lower than 185 W [17,18,19]
Summary
Heavy Liquid Metals (HLM) are usually employed as spallation materials and coolants in spallation targets, which are key components of neutron sources and Accelerator-Driven Systems (ADSs) [1,2]. In such systems, high-power pulsed proton beams are injected into the HLM to initiate the spallation reaction, to produce neutrons exhibiting various spectra for frontier scientific and industrial applications. The collapse of a cavitation bubble close to the HLM container wall, after reaching its maximum radius, causes cavitation damage on the wall It is well-known that, in addition to the pressure waves, turbulent HLM flow can create a negative pressure in liquid. The effects of flow fluctuation on cavitation bubble dynamics in an orifice-like structure are discussed as well
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