Monitoring coolant gas composition at TBM-like operating conditions

Abstract When helium cooled test blanket modules (TBM) are tested in ITER, the gas composition has to be monitored constantly. In this paper, we present results of measurements performed with a mass spectrometer, while the Helium Loop Karlsruhe (HELOKA) facility was operated at TBM-like conditions (300 °C – 400 °C and 8 MPa). An accuracy of 1 ppmv or lower is reachable with a well calibrated instrument. Measurements are reproducible and can be automated. The measurements showed that the loop filling procedures ensure that the helium stream in HELOKA has a low level of impurities in the range of 0.02 % even after long time operation.