Fusion Science and Technology / Volume 41 / Number 3P2 / May 2002 / Pages 764-775
Hydride and Storage / Proceedings of the Sixth International Conference on Tritium Science and Technology Tsukuba, Japan November 12-16, 2001
Titanium was selected for evaluation as a tritium storage material. Titanium-deuterium desorption isotherm data at 550, 600, 649, 700, and 760°C are presented and were used to evaluate storage vessel design loading limits. Two prototype Hydride Storage Vessels (HSVs) containing a nominal 4400 grams of Ergenics HY-STOR 106™ titanium sponge were tested to determine activation, loading, and desorption conditions. HSV titanium activation was performed using two methods. The first was vacuum evacuation using stepped temperature holds up to 600°C. The second, and preferable method, was a dry gas purge for several hours at up to 350°C followed by heated evacuations at temperatures up to 600°C. The vessels were allowed to sit idle after activation for five days before loading to determine the quality of the activation process. HSV gas loadings were performed through the process tube inserted into the hydride at 5, 7.5, 10, 15, 20 SLPM, and under conditions to simulate direct loading from a 1500 liter process tank. Temperature measurements made at various locations around the vessel showed the internal maximum temperature ranged from 500°C to 700°C and varied with loading rate. Maximum external temperatures ranged from 300°C at 5 SLPM to 400°C at 20 SLPM. Loading the HSV at 20 SLPM from the tube above the level of the hydride generated at maximum internal temperature of 800°C. HSV desorptions were done under a variety of vacuum conditions at temperatures up to 700°C. HSV desorption/gas removal was greatly reduced at temperatures below 700°C, the use of one instead of both process tubes, and the choice of vacuum pumps. Integration of mass flow data was considered a more reliable method of determining HSV gas inventory than the use of titanium isotherm data. Up to 84 vol% of the gas inventory can be removed from the HSV by desorption in 24 hours, but tritium removal by isotopic exchange will be needed for vessel disposal - even if longer evacuation times were used.