In-Situ Ultrahigh-Pressure Waterjet Peening of Nuclear Reactor Internals for the Prevention of Stress Corrosion Cracking

114 In-Situ Ultrahigh-Pressure Waterjet Peening of Nuclear Reactor Internals for the Prevention of Stress Corrosion Cracking--Waterjet Technology, Inc., 21414 68th Avenue South, Kent, WA 98032-2439; (206) 872-1925 Mr. David Monserud, Principal Investigator Ms. Diana Suzuki, Business Official DOE Grant No. DE-FG03-97ER82509 Amount: $74,879 Periodic inspection of commercial nuclear power pressure vessels has revealed an increasing occurrence of stress corrosion cracking in weld areas and irradiation-assisted cracking in non-weld areas. The continued safe and economic operation of nuclear powerplants depends on industry effectively addressing this problem. A novel ultra-high pressure waterjet peening process represents an economical solution by conditioning existing reactor internal components in place to prevent stress corrosion cracking. Using waterjets that operate at 55,000 pounds per square inch, this process imparts surface stresses on metal components similar to those resulting from traditional shot peening. Traditional shot peening stops stress corrosion cracking, but the method is not accepted for this application because abrasive particles and air are released. The Phase I feasibility effort will be directed toward the demonstration and experimental characterization of the peening effort in cold working metal surfaces without removing any material. An optimized peening nozzle will be developed, and the test results will be used to generate a conceptual design for the commercial system. In Phase II, a prototype full-scale peening system will be designed and built, and factory and field testing will be conducted. Commercial Applications and Other Benefits as described by the awardee: This technology will enable the continued safe and economic operation of both commercial and military nuclear facilities by preventing both weld-sensitized and irradiation-assisted stress corrosion cracking in reactor internal components. The process will be applicable to any boiling water or pressurized water reactor design. Benefits may include the mitigation of existing intergranular corrosion and radiation-induced segregation. The use of only ultra-high pressure water will facilitate packaging a small yet powerful tool capable of conditioning a wide variety of surfaces in crowded reactors. Such a tool will be economical for ownership by both nuclear service companies and reactor utilities themselves.