Leak evaluation in JET and its consequences for future fusion machines
During the assembly of the vacuum vessel and the subsequent operation of JET, hundreds of vacuum leaks were found and repaired. Information on leaks has been collected and evaluated since 1981 in an attempt to reveal the causes. In this evaluation a clear distinction was made between leaks occurring during the installation and during the plasma operation phase. Most installation leaks on flanges appeared to be caused by incompatible seals, damage or contamination of the sealing surfaces. Leaks in welded connections were mostly due to impurities, incompatible welding materials or inaccurate setting of the welding parameters. The difficulty of access to flanged or welded connections proved to be responsible for the occurrence of leaks during assembly. Operational leaks were in general the result of design errors, problems with bellows (in particular bellows in water cooling systems ) and mechanical forces on the equipment due to uncontrolled plasma behaviour (disruptions). Recommendations are made on leak prevention for the radioactive tritium phase of JET and for future machines.
Bibliographic Reference: Report: JET-P(89)57 EN (1989)
Availability: Available from the Publications Officer, JET Joint Undertaking, Abingdon, Oxon. OX14 3EA (GB)
Record Number: 199010426 / Last updated on: 1994-12-01
Original language: en
Available languages: en