Upgrade of main separation planes (HDR) of steam generator primary and secondary headers and side manholes

Repairs performed during the Bohunice V-1 reactor and Bohunice V-2 reactor operation are briefly described. Grooves were repaired in all headers in turn. Crack indications were found in the border area between the austenitic weld deposit and the basic material, and the sealing surfaces of primary header covers were repaired by local grinding-out and welding. Special devices and technologies were developed for this purpose. An upgrade of the main separation planes was elaborated in order to replace nickel seals with graphite-based seals. The upgrade technology has already been applied to 2 pieces of primary header covers, the other upgrade technologies will be applied starting from 1999. (M.D.)