Tritium concentration monitoring of the purge gas stream of HCPB breeder blankets in future fusion reactors

In fusion technology it is necessary to monitor tritiated gases for process monitoring. Such a system should be able to monitor the gas without taking samples. It should also be compact, cheap, the system stability should be excellent and it should recognize changes in the activity fast. Standard tools for activity measurements are ionization chambers and calorimeters. Ionization chambers work without sample taking but they are gas species dependent. Also pressures in the 100 mbar range are needed. Calorimeters are not suitable to be used as process monitors and it takes several hours to get a result. For activity measurements with a calorimeter it is necessary to extract gas samples. The Tritium Activity Chamber Experiment (TRACE) is a specially designed prototype to monitor traces of tritium in a gas sample utilizing Beta Induced X-Ray Spectroscopy (BIXS). Future fusion plants like ITER or DEMO could use such a system to monitor the purge gas streams in HCPB breeder blankets. TRACE will explore the possibility to monitor the expected 10 ppm tritium in the helium purge gas stream. We will evaluate if a BIXS system can be used as a standard monitoring system for tritiated gases in the range of (10^-5-10⁰) mbar tritium partial pressure.