Gas circulator repairs

The failure in May 1983 of the thrust bearing of a gas circulator on one of the Magnox gas-cooled reactors at Oldbury-on-Severn power station gave rise to a series of problems not previously experienced in the maintenance and repair of circulators. Investigations to discover the extent of damage revealed defects that were traced back to original manufacturing standards and testing procedures. The thrust bearing failure prompted a more critical examination of maintenance dismantling/rebuild procedures and standards, leading to changes in the organization and quality control of circulator maintenance activities. A longer-term programme to improve the build standards of all the eight gas circulators has been adopted. (author)