Tritium evacuation performance of a large oil-free reciprocating pump

A large oil-free reciprocating pump, with carbon polyimide composite piston rings and dynamic metal bellows seal, has been developed for tritium services at the Tritium Process Laboratory of the Japan Atomic Energy Research Institute. The design pumping speed is 54 m3 h−1 for hydrogen gas at 5 Torr suction pressure and 875 Torr discharge pressure. Tritium evacuation performances were measured at 400–675 Torr discharge pressure at the Tritium Systems Test Assembly (TSTA) of the Los Alamos National Laboratory under the US-Japan collaboration programme on fusion fuel technology. The pumping speed for tritium was greater than 120 m3 h−1 at 4 Torr suction pressure and 500 Torr discharge pressure. The ultimate pressure with tritium was 0.8 Torr at 500 Torr discharge pressure. Performance data for tritium were slightly better than those for H2, D2, He and N2. The discharge pressure did not affect the evacuation performance. In order to check the long-term effect with tritium on pump, semicontinuous tritium pumping operations were performed for a total of 350 hours within 3 months. However, no performance changes were found. After stand-alone tests, the pump was successfully demonstrated as a DT fuel vacuum and transfer pump during a TSTA loop run.