20 PWR Reactor Vessel Integrity and Internals Aging Management
Download citation file:
- Ris (Zotero)
- Reference Manager
The integrity of the reactor pressure vessel is critical to plant safety. A failure of the vessel is beyond the design basis. Therefore, the design requirements for vessels have significant margins to prevent brittle or ductile failure under all anticipated operating conditions. The early vessels in the United States were designed to meet the requirements of ASME BPVC Section VIII. The design requirements for these vessels were supplemented by special requirements based on earlier U.S. Navy design experiences. In general, the allowable stress limits were lower than vessels designed to later ASME BPVC Section III requirements. The early design codes did not include the rigorous fracture toughness requirements found in today's codes. Section VIII relied on a “fracture-safe” design approach, which sought to ensure that pressure vessels were operated in a temperature regime (upper-shelf region) where small flaws or cracks would not affect the load-carrying capacity of the structure.