Document: NUREG-0800
Document ID: c9c204f0-a162-491c-8c25-ee0418212f29
Document Type: srp
Title: PRESSURE-TEMPERATURE LIMITS, UPPER-SHELF ENERGY, AND PRESSURIZED
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0703/ML070380185.pdf
Revision Date: 2023-06
Chapter: 5
Section ID: 5.3.2
CFR Part: 
CFR Title: 

Content:
dix G provides assurance regarding the structural integrity of the RCPB and, specifically, the reactor vessel. The next item discusses the technical rationale for this rule. 5.3.2-8 Revision 2 - March 2007 5. Appendix G to 10 CFR Part 50 establishes that the pressure-retaining components of the RCPB that are made of ferritic materials must meet requirements of the ASME Code, supplemented by the additional requirements set forth in Appendix G to 10 CFR Part 50 for fracture toughness during system hydrostatic tests and any condition of normal operation, including anticipated operational occurrences. Fracture toughness properties of ferritic materials increase significantly above the point referred to as the nil-ductility transition temperature. This temperature is established for the RCPB material in accordance with Section XI of the ASME Code, as supplemented by the requirements of Appendix G to 10 CFR Part 50. The P-T limits established in accordance with the ASME Code and Appendix G to 10 CFR Part 50 are used to establish operating parameters that provide assurance that the RCPB will act in a nonbrittle manner when subjected to stresses associated with normal operations, maintenance, testing, and anticipated operational occurrences. The P-T limits must be adjusted to account for the effects of radiation embrittlement of the RCPB materials over the life of the plant. Compliance with the requirements of Appendix G provides a method of satisfying the requirements of GDC 14 and 31 with regard to ensuring that the RCPB acts in a nonbrittle manner and that the probability of rapidly propagating failure and gross rupture of the RCPB is extremely low. 6. 10 CFR 50.61 establishes fracture toughness requirements for protection against PTS events, which involve transients in PWRs that cause severe overcooling in conjunction with overpressurization. The thermal stresses in combination with the pressure stresses increase the potential for brittle fracture in the presence of an