Tritium management in HCLL-PPCS model AB blanket

Abstract

When dealing with activities related to the design and optimisation of the Helium Cooled Lithium Lead (HCLL) blanket, doubts arose in the past about the technical feasibility of the tritium processing system. The questionable feasibility was due to the heavy performance requirements for different tritium processing subsystems, mainly consequence of the high tritium permeation rate from the breeding blanket into the main cooling circuit, which was claimed as an intrinsic characteristic of such a blanket concept. This was directly related to the supposed very low tritium solubility in the liquid lead lithium in eutectic composition. Recent data on the hydrogen-PbLi Sieverts’ constant achieved at ENEA CR Brasimone are one order of magnitude higher than those so far assumed as reference. Because of the consequent much lower tritium permeation rate from the liquid metal into the primary cooling circuit, the performance requirements for the main tritium processing subsystems/technologies in HCLL blanket for PPCS reactor are significantly relaxed. Nevertheless, further efforts have to be focused in lowering the required Coolant Purification System (CPS) feed flow-rate which still remains the most critical tritium processing subsystems.