Design improvements and lessons learned for the TFTR Tritium Cleanup and Gas Holding Tank Sampling systems

Abstract

Key to the Deuterium-Tritium operations at TFTR has been the support provided by the Tritium Cleanup System, (TCS) and the associated Gas Holding Tank (GHT) and Sample Loops. The TCS disposes of hydrogen waste products from the Torus by oxidizing them over a catalyst and then absorbing the resulting moist gas onto molecular sieve. The GHT Sample Loops provide the analytical capabilities required to measure gas composition and activity in the GHTs before the gas is passed into TCS. At present we have accumulated significant operating experience running tritium through both TCS and the GHT Sample Loops. As experience has been gained we have made improvements to the system hardware resulting in increased reliability and performance. Hardware changes include the upgrading to metal bellows type vacuum pumps, the addition of service ports for enhanced maintenance capabilities, and improvements made to the diagnostic capabilities for the GHT Sample Loops. The operation of TCS has also provided us with lessons learned in trouble shooting some interesting problems, one being the introduction of sulfur hexafluoride, an insulating gas used in the Neutral Beam system, into TCS and it's effect on the platinum catalyst. Other areas of interest include the experience gained in the continuing task of identification and repair of leaks in the system, and the challenge of instrumentation and flow control with varying gas densities.