Impact of low PRF tritium permeation barriers-on the water cooled lead lithium blanket: A safety analysis

A summary is here presented concerning the first results in evaluating the safety features of the European water-cooled lead lithium blanket in which tritium permeation barriers on the external surface of the breeder cooling pipes are not used or, if used, a lower efficiency is required for them. As a consequence, in this design concept, a significant amount of tritium must be recovered through the water detritiation system. The technical and economical feasibility of such a tritium management strategy was demonstrated up to a tritium permeation rate of 10+15 g/day, accepting, at the same time, a higher tritium activity in the primary coolant in order not to overload the water detritiation system. A safety analysis has then been performed to evaluate the impact of a higher tritium specific activity in the primary coolant, both in normal operation and in accidental condition. Tritium release to the environment in case of a LOCA was found to satisfy the limits recommended by the ITER Project Design Guidelines for accidental tritium release, while the respect of the limits for chronic release strongly depends on the water leak rate from the primary to the secondary circuit.