Development of permeation based hydrogen isotopes sensor and its testing in gas phase and molten Pb-Li

For any nuclear fusion reactor, accurate measurement of bred tritium in the breeding blanket plays a key role for tritium management. These breeding blankets consist of mainly two types of tritium breeders. One is solid breeders, mainly lithium-based ceramic pebbles, and another is liquid breeders, the composite of lithium-based alloys. In a liquid-based breeding blanket, among various proposed breeding materials, a Pb-Li eutectic alloy is one of the most acceptable material in fusion reactors due to its good thermo-physical properties as well as its multiple applications, such as tritium breeder, neutron multiplier and coolant. However, the measurement of bred tritium in molten Pb-Li is equally challenging for any electronic diagnostics due to high-temperature compatibility issues and the corrosive nature of molten Pb-Li. Such a molten Pb-Li compatible sensor is not available commercially either. Therefore, the need for the development of a highly reliable and molten Pb-Li compatible sensor with a fast response time is obvious. Institute for Plasma Research (IPR) has designed, developed, and tested the permeation-based hydrogen isotope sensor in the gas phase (in UHP (Ultra High Pure) hydrogen gas) as well as in the liquid phase (in molten Pb-Li). In the present work, the experimental details, including testing setups for both gas phase and molten Pb-Li phase along with their testing results, are discussed.