Assessment on F/W electrical cutting for reduction of electromagnetic force on the blanket module

For mitigating the electromagnetic (EM) force acting on the first wall (F/W) during plasma disruption, effects of toroidally electrical cutting slits on copper heat sink of F/W have been investigated by EM analysis of the blanket module designed for the International Thermonuclear Experimental Reactor (ITER). The analytical studies include 1) effects of F/W material and its thickness on eddy current reduction, and 2) effects of number of toroidal cutting slits on copper heat sink and of gap length of the slit on the eddy current reduction in the copper heat sink. The following conclusions were obtained and the effectiveness of toroidal cutting of copper heat sink was clarified by a series of analyses; a)A change of F/W material from copper alloy (DSCu) to SS316 decreases the eddy current and electromagnetic force on the F/W at plasma disruption. In the case of SS316, reduction effect is remarkable in the range of the thickness less than 50mm. b)Toroidal cutting on F/W DSCu region can reduce total eddy current acting on the F/W. By increasing number of toroidal slits with 1mm gap length up to 17 (corresponding to maximum limit), about 60% of the eddy current in the F/W runs away through the SS316 support plate located at the behind of copper alloy heat sink. (author)