Summary report for 1990 inservice inspection (ISI) of SRS 100-K reactor tank

The integrity of the SRS reactor tanks is a key factor affecting their suitability for continued service since, unlike the external piping system and components, the tanks are virtually irreplaceable. Cracking in various areas of the process water piping systems has occurred beginning in about 1960 as a result of several degradation mechanisms, chiefly intergranular stress corrosion cracking (IGSCC) and chloride-induced transgranular cracking. The purpose of this inspection was to determine if selected welds in the K Reactor tank wall contained any indications of IGSCC. These portions included areas in and beyond the weld HAZ, extending out as far as two to three inches from the centerline of the welds, plus selected areas of base metal at the intersection of the main tank vertical and mid-girth welds. No evidence of such degradation was found in any of the areas examined. This inspection comprised approximately 60% of the accessible weld length in the K Reactor tank. Initial setup of the tank, which prior to inspection contained Mark 60B target assemblies but no Mark 22 fuel assemblies, began on January 14, 1990. The inspection was completed on March 9, 1990