Optimization of design of the LBE spallation target at JAEA

Wan, T.; Obayashi, Hironari  ; Sasa, Toshinobu   

Japan Atomic Energy Agency (JAEA) will build a spallation target in Japan Proton Accelerator Research Complex (J-PARC) to perform basic R&Ds for future Accelerator Driven Systems (ADSs). A Lead-Bismuth Eutectic (LBE) spallation target with a Beam Window (BW) will be bombed by high-power pulsed proton beams. However, it was found that the original LBE target design leads to some stagnant/re-circular flow regions in LBE and an extreme off-balance flow pattern in the annular flow channel. In the present study, optimization of the entire target design was performed on the basis of the target head design experiences obtained in our former studies. Efforts were focused on to eliminate those stagnant/re-circular flow regions and to balance the flow velocity in the annular flow channel. Parameters having impacts on the LBE flow pattern were systematically investigated. A number of case studies were performed and several original design measures were figured out to optimize the LBE flow behavior. Thermal-hydraulic and structural analyses results showed that the stagnant and re-circular flow regions can be reduced effectively, and a relative balance LBE flow can be obtained in the annular flow channel due to the modified designs. Maximum temperature and generated stress on BW have been greatly reduced. The updated target design improves the target safety margin.