Professor and Director, Staatliche Materialprüfungsanstalt, University of Stuttgart, Stuttgart,
Pages: 14 Published: Jan 1983
The structural integrity of pressure vessels of light-water reactors is decisively controlled by the ductility of the vessel material. Layout and design principles as well as the chemical composition of the materials have been optimized for new plants as redundant measures to assure sufficient toughness during the whole lifetime history, an approach termed the Basis Safety Concept.
Adequate measures had to be taken to sustain the necessary safety margin in two older vessels that did not meet these advanced requirements. The necessary safety has been achieved by changing the core configuration to reduce the end-of-life fluence and thus limit the loss of toughness, and setting pressure and temperature limits on the heat-up and cool-down procedure to assure the load path, as well as by instituting an enhanced nondestructive evaluation program, especially on the joint weld of the belt line region, as a basis for fracture mechanics analysis.
Apart from surveillance and plant-specific irradiation programs, additional research and development programs are being performed to investigate irradiation damage by means of linear elastic and elastic-plastic fracture mechanics.
light water reactors, pressure vessel steels, irradiation embrittlement, surveillance programs, fracture mechanics, annealing
Paper ID: STP31849S