Cold trap and cryogenic molecular sieve adsorber: components for tritium extraction from the purge gas of the HCPB-breeder blanket for ITER

The helium purge gas loop for tritium extraction from the ceramic breeder blanket (Helium Cooled Pebble Bed, HCPB) of ITER (International Thermonuclear Experimental Reactor) includes as main components a liquid-nitrogen cooled cold trap (CT) for the retention of tritiated water produced in the breeder, and a liquid-nitrogen cooled molecular sieve adsorber bed to extract various isotopic species of hydrogen (H2, T2, HT) as well as N2 and O2. In a preliminary test rig, a CT was operated under once through conditions to obtain data for the final design. The results of humidity measurements confirm the efficiency of the system. To demonstrate hydrogen extraction from a helium gas flow at the operating temperature of 78 K, the test rig will also include a liquid-nitrogen cooled adsorber bed designed and constructed at the Forschungszentrum Karlsruhe. As the next step, a test facility on a technical scale (one-sixth of the flow rate of the ITER-HCPB) will be built in a glovebox in the Tritium Laboratory Karlsruhe (TLK) for tritium experiments with the two main components of the extraction process, i.e. the CT and the molecular sieve bed.