Optimum design of beam window's diameter and thickness of Hyper target system

HYPER is designed to transmute long-lived TRU and fission products such as Tc-99 and I-129. Pb-Bi is used as the coolant and spallation target material at the same time. HYPER is expected to need about 20mA proton beam to sustain a 1000MWth power level. The cylindrical beam tube and spherical window is adopted as the basic window shape of HYPER. The window diameter and the window thickness are varied to find the maximum allowable current based on the design criteria : Pb-Bi temperature < 500 .deg. C, window temperature < 600 .deg. C, Pb-Bi velocity < 2m/s and window stress < 160MPa. The LAHET code is used to simulate heat generation. CFX is also used for the thermal-hydraulics calculation. Based on our design criteria, the maximum allowable current is calculated to be about 9.2mA, which is smaller than the required current. Therefore, an upgrade of the target system design is required