Chemical decontamination of BWR fuel and core materials: Examination of irradiated stainless steel specimens: Interim report

Dilute chemical decontaminations using AP-LOMI and Ap-CAN DECON solvent were performed on mill annealed, irradiated Type 304 stainless steel to evaluate its effect on surface corrosion and intergranular stress corrosion cracking (IGSCC). Constant extension rate tensile (CERT) specimens were fabricated from an irradiated tie rod of a La Crosse control blade. These specimens were then mounted on the fuel channel of a spent fuel bundle. These specimens and spent fuel bundles were decontaminated in the spent fuel pool at Quad Cities Nuclear Power Plant. The decontaminated CERT specimens were then returned to the GE Vallecitos Nuclear Center for evaluation. The specimen surfaces were examined following CERT SCC testing in a simulated BWR coolant environment. All the testing and examinations were remotely conducted in the hot cell. The surface examinations provided an assessment of chemical attack, particularly intergranular attack (IGA) during the decontamination processing. The CERT tests provided an assessment of any possible degradations of IGSCC resistance following decontaminating. Results of post-decontamination evaluation indicated that neither the AP-LOMI nor AP-CAN DECON processes led to any chemical attack or evidence of IGA. Irradiation assisted IGSCC was observed on all of the specimens tested in water with 8 ppm dissolved oxygen. However, the two dilute chemical decontaminations did not affect IGSCC susceptibility. 4 refs., 17 figs., 4 tabs