Leak detection system in ITER

This article describes the current design status of a leak detection system in International Thermonuclear Experimental Reactor (ITER). The ITER leak detection system is comprised of residual gas analyzers (RGAs) and mass spectrometer leak detectors (MSLDs) with different specifications, and targets leaks in the torus, cryostat and other miscellaneous components. For fine leak testing in the torus and cryostat, a 4He background gassing rate (Qback) will be a dominant factor in determining an actual time response of the leak detection system. The Qback should be reduced to less than 10−12 Pa m3 s−1, in order to achieve a reasonable time response of ∼90 s for a 10−8 Pa m3 s−1 4He leakage. To eliminate the drain and dry out scheme of the leak checking procedure for the torus in-vessel water cooling circuits, a spiking method, which adds some soluble tracers to circulating waters, has been proposed although further R&D is required.