RW undertook a comprehensive technical programme to assess the suitability one of our alloys as a sealing solution for our nuclear decommissioning customers. The work focused on verifying sealing performance, material behaviour under nuclear relevant scenarios. This programme responded to the needs of nuclear customers who require highassurance, evidence based justification before adopting new technologies. The alloy seal needed to maintain integrity under plant operating pressure cycles, temperature variations, radiation exposure and corrosion environments.
Pressure cycling
M3Spray seals were applied on representative stainless steel pipe defects and tested up to 15 bar, achieving 100% leak mitigation. Specimens were then subjected to a pressure cycling regime representing 8.5 years of plant operation ranging between 1.5 bar and 8 bar. The seal maintained complete integrity throughout.
Temperature Cycling
Both M3Spray and M3Cast samples were put through temperature cycles representing extreme weather conditions over ten plus years. Seal performance at operating pressure was unchanged after 20 years of cycles, and at 10 bar, multiple times operational pressure, minor degradation was seen.
Radiation Exposure
Specimens of alloy on polyethylene, cast iron and stainless steel substrates were exposed to Co60 gamma radiation up to 56.8 kGy. Results showed no material degradation when analysed after exposure, and demonstrated a beneficial shielding effect.
Galvanic and Atmospheric Corrosion Testing
Galvanic testing of alloy with 304SS and cast iron in seawater and caustic environments showed low and decreasing galvanic currents, indicating insignificant longterm galvanic corrosion effects.
Atmospheric corrosion testing in a yearlong UK coastal exposure of a M3Cast seal demonstrated stable performance, with only minor surface deposits seen, and improving leak sealing performance at 10 bar during post exposure retesting.
Conclusion
Across all testing streams, the alloy seal maintained consistent sealing performance under operational cycling, radiation, and corrosion inducing environments. The findings provide a strong technical basis supporting the alloy’s use in nuclear decommissioning environments.
