ICONE19-43941 DESIGN STUDY FOR BEAM WINDOW OF ADS AND DEVELOPMENT OF LBE FLOW MEASUREMENT TECHNIQUES

Abstract

Accelerator Driven System (ADS) has been developed in JAEA. In this system, liquid Lead Bismuth Eutectic (LBE) alloy would be used for a coolant and a spalltion neutron target materials. For the feasibility of ADS, the study for the design of a beam window, which is the boundary between an accelerator and a subcritical core, is an important factor. At first, the characteristics of the thermal-fluid behavior around the beam window with the proton beam were simulated by CFD analysis. The structural strength of the beam window was estimated by using the CFD results. In this analysis, the dependency of the thermal-fluid behavior by the profile of the proton beam was investigated by changing from a Gaussian profile to a parabolic and a flat one. In the parabolic case, the thermal stress at the top region of the beam window was reduced, and the buckling pressure increased about 20%. However, because of a lack of the experimental data for the validation of this numerical analysis, the estimation for the reliability of a beam window design was not enough. Furthermore, because of the high Re k-ε model used for the CFD analysis, these results given by the consecutive analysis were only averaged evaluation. For the feasibility of ADS, the corrosion of the material in the LBE is also significant issue. If the Oxygen concentration in LBE is extremely low, the surface of materials catches the fatal damage by the flowing LBE. In the diffuser section in JAEA Lead Bismuth Loop-1(JLBL-1) which has been used for the study of the erosion/corrosion, serious erosion was observed. The erosion was caused by the local flow structure and such as a vortex. Thus, it is extremely important to expand the experimental data of the flowing LBE to grasp the local flow structure. However, the flow measurement of the general liquid metals in a high temperature condition was difficult because of its physical characteristics. The flow measurement techniques for LBE flow has been developed by using Ultrasonic Velocity Profiling (UVP) method. UVP is a suitable tool to measure an instantaneous space-time velocity profile especially on a velocity measurement of an opaque liquid flow, such as liquid metal. A developed system realizes the measurement of the velocity vector profiles including the information of the three velocity component simultaneously on time. This system was successfully applied to the actual LBE flow.