BB LOCA analysis for the reference design of the EU DEMO HCPB blanket concept

Abstract

Following DEMO configuration in 2015 the design of the Helium Cooled Pebble Bed (HCPB) blanket concept has been significantly improved. For the reference design HCPB2015V3 and the associated primary heat transfer system (PHTS) the breeding blanket (BB) loss of coolant accident (LOCA) has been investigated as the design basis accident (DBA). System code MELCOR186 for fusion is used for the LOCA simulation. The LOCA can take place in the breeder zone (BZ) or in the first wall (FW) of the BB, and it is assumed to be in one affected equatorial blanket module (BM) on the outboard (OB). Different scenarios due to break sizes and plasma shutdown conditions are taken into account. He inventory during normal operation is determined as steady state results. Transient results of LOCA are evaluated for the mass flow rate, pressure, helium temperature, structure temperature and mass. Finally, issues encountered in this analysis are discussed.