| Abstract Scope |
Helium cooled, high-temperature gas reactors are a proven power generation technology that is being commercialized for widescale deployment by X-energy. Due to the unique advantages of helium gas as a coolant, system temperatures range between ~285-750°C and require a variety of structural alloys from conventional pressure vessel steels to highly alloyed iron-based and nickel-based alloys. For the pressure vessel steels, few issues exist in weldability or weld performance as their use in the Xe-100 reactor system is bounded by light water reactor experience. For the 316H austenitic stainless steel used in the steam generator system, weldability is well understood and stress relaxation cracking can be mitigated by design and fabrication. However, the Alloy 800H used in the hottest parts of the system presents unique challenges as the alloy does not have an ASME code-qualified matching filler metal, it’s susceptibility to stress relaxation cracking is known but has not been quantified, and degradation in helium gas is a potential concern. This presentation discusses how X-energy is mitigating these gaps to ensure the long term performance of structural alloys and welds in the Xe-100 reactor system. |