Incidence of Intergranular Stress Corrosion Cracking (IGSCC) In Reactor Tanks and Piping.

摘要

Visual inspections of welds in the walls and around the outlet nozzles of the reactor tanks have been conducted on a regular basis since the mid-60's. No cracks have been detected during these inspections, nor by limited dye penetrant inspection of welds in L- tank. Furthermore, no leaks have been detected in P-K-L reactor tanks over the operating life of the reactors. The knuckle in C-tank provides the only case of a tank leak and associated intergranular stress corrosion cracking (IGSCC). In contrast, IGSCC has been found by ultrasonic examination (UT) in the heat-affected-zones (HAZ) of approximately seven percent of the circumferential welds in process water piping that is 12-inch diameter and larger. Several small leaks have been detected and sections of pipe replaced. The behavior of the tanks and pipes appears contradictory as the conditions that are necessary for IGSCC are expected to be present in both the tanks and the pipes. The current study was undertaken to explore the parameters that influence IGSCC to identify factors that would explain the apparent difference in the incidence of IGSCC in the tanks and pipes. (ERA citation 13:053838)