Leak detection system in ITER

摘要

This article describes the current design status of a leak detection system in Internationa1 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 4~He background gassing rate (Q...,) will be a dominant factor in determining an actual time response of the leak detection system. The Q..., should be reduced to less than 10~-l2 Pa m~3 s~-1, in order to achieve a reasonable time response of ~ 90 s for a l0~-8 Pa m~3 s~-l ~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 circu1ating waters, has been proposed although further R&D is required.