RESULTS OF RESEARCH-AND-DEVELOPMENT FOR LITHIUM VANADIUM BREEDING BLANKET DESIGN/

The self-cooled lithium/vanadium blanket concept has several attractiv e features for fusion power systems, including reduced activation, res istance to radiation damage, accommodation of high heat loads and oper ating to temperatures of 650-700 degrees C. The primary issue associat ed with the lithium/vanadium concept is the potentially high MHD press ure drop experienced by the lithium as it flows through the high magne tic held of the tokamak. The solution to this issue is to apply a thin insulating coating to the inside of the vanadium alloy to prevent the generation of eddy currents within the structures that are responsibl e for the high MHD forces and pressure drop. This paper presents the p rogress in the development of an insulator coating that is capable of operating in the severe fusion environment, progress in the fabricatio n development of vanadium alloys, and a summary of MHD testing. A larg e number of small scale tests of vanadium alloy specimens coated with CaO and AlN have been conducted in liquid lithium to determine the res istivity and stability of the coating. In-situ measurements in lithium have determined that CaO coatings, similar to 5 mu m thick, have resi stivity times thickness values (pt) exceeding 10(6) Omega cm(2). Thes e results have been used to identify fabrication procedures for coatin g a large vanadium alloy V-4Cr-4Ti) test section that was tested in th e ALEX (Argonne Liquid metal Experiment) facility. Similar test sectio ns have been produced in both Russia and the USA. (C) 1998 Published b y Elsevier Science S.A. All rights reserved.