Remote maintenance issues concerning vacuum pumping system isolation: regeneration gate valves proposed for experimental fusion reactors

Large diameter gate valves suitable for high vacuum operation are being studied for application to primary exhaust systems proposed for large fusion reactors. The valves must be leak-tight, radiation resistant, and dust tolerant. Remote exchange of the valve internal working parts (disc/seal) is also a requirement. This paper describes remote maintenance techniques for the handling of the valve internals in inert gas at atmospheric pressure when the reactor is shut-down. An alternative handling method is described which provides for seal exchange while under vacuum. Remote inspection of the valve seating surfaces and seals is also described. (author)