Tritium Recovery from a Solid Breeder Demo Blanket

The main task of a Tritium Extraction System (TES) for a helium cooled Li₄SiO₄ DEMO blanket is the tritium recovery from a purge gas stream. On the basis of several TES proposals published for a NET/ITER solid breeder blanket, a new concept has been developed which is especially appropriate to cope with large purge gas streams.

As tritium is expected to appear in two chemical forms (HT and HTO) two specific process steps are used for its removal from the primary purge gas loop: a cooler to freeze out Q₂O at 173 K (Q = H,T), and a molecular sieve bed to absorb Q₂ at 78 K.

Only these components including some additional devices for the gas pre-conditioning like a compressor and a precooler, are subjected to the high gas flow rates mentioned above. All further processing is done in relatively small secondary loops during and after warmup of the cooler and the molecular sieve bed. Q₂O reduction by using the water gas shift reaction, and separation of Q₂ with Pd/Ag diffusors are the main process steps in the secondary loops.

The feasibility of the proposed method is very promising as all process steps are based on well known technical and radiochemical experience.