Forces on the Jet vacuum vessel during disruptions and consequent operational limits

Disruptions at high current cause large forces and stresses at the JET vessel. Particularly undesirable are vertical disruptions due to possible failure of the vertical stabilisation system. Forces and stresses are being assessed on the basis of magnetic measurements, vessel deflections, strain gauge measurements at vertical supports and by a finite element mechanical analysis. The present operating restrictions may be relaxed after implementation of two support rings at the inner periphery of the vessel which supplement those at the outer periphery and will prevent unacceptable radial deflections