Two Midwestern nuclear plants have hired a Mitsubishi Heavy Industries subsidiary to conduct a water-jet peening process previously used in Japan to treat reactor components susceptible to stress corrosion cracking. The Wolf Creek plant, majority owned by Kansas City Power & Light and Kansas Gas & Electric, and the Callaway plant, owned by Ameren, have hired Mitsubishi Nuclear Energy Systems to treat reactor components during their next refueling outages. Both are single-unit plants using Westinghouse pressurized water reactors in Kansas and Missouri, respectively.The peening will reduce the potential for stress corrosion cracking in alloy 600 reactor pressure vessel components. Alloy 600 is a nickel-based alloy that can eventually become susceptible to cracking under certain conditions. According to the Nuclear Regulatory Commission, its condition and maintenance in operating reactors has been closely watched for 25 years.MHI has used the water peening process to modify components in 21 pressurized water reactors in Japan, according to a release issued Wednesday. Submerged, remotely controlled equipment uses only high-pressure water to modify the metal, with no heat or foreign material applied to the reactor. Terms of the contract were not announced. AZZ WSI of Norcross, Ga., and Structural Integrity Associates of San Jose, Calif., will perform the work using MHI equipment.
They should be using low plasticity burnishing. From what I understand, it achieves significantly deeper compression and is far more effective at preventing and stopping SCC.
Low plasticity burnishing sounds ok for factory fabrication - but can it be performed underwater in-situ?
lpb in theory can be performed underwater in-situ. However, it is based on physical geometry, so the feasibility depends on the component being worked.