Preparation and analysis of helium purge gas mixture to be used in tritium extraction system of LLCB TBM

Hydrogen isotopes are extracted from the ceramic breeder and liquid breeder zones of Lead Lithium Ceramic Breeder (LLCB) Test Blanket Module (TBM) with Helium purge gas. 1000 ppm of hydrogen gas is mixed with the purge helium gas to facilitate improved extraction of hydrogen isotopes due to hydrogen swamping reactions. An experimental set-up is developed for making up the purge gas mixture with a composition similar to the purge gas composition provided at the inlet of the ceramic breeder zones and detritation column of LLCB TBM. This is achieved by introducing different ppm levels (500-5000 ppm) of hydrogen in helium gas by flow control mechanism. The analysis of the purge gas mixture is performed using a highly sensitive gas chromatograph system. In this work, parametric analysis is performed to optimize the process parameters viz., flow rates, temperatures etc. for achieving the required mixture of hydrogen and helium. This paper describes the detailed design of the experimental set-up along with parametric analysis results leading to optimized experimental conditions. (author)