Document: NUREG-0800
Document ID: 9b735916-a58a-4bd3-b7e0-826b84cb6e43
Document Type: srp
Title: FRACTURE PREVENTION OF CONTAINMENT PRESSURE BOUNDARY
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070465.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.2.7
CFR Part: 
CFR Title: 

Content:
ocess as an engineered safety feature, as is, for example, the emergency core cooling system. Regulatory Guide 1.26 is silent with respect to the containment pressure boundary, but does assign Group B Quality Standard to the emergency core cooling system. Regulatory Guide 1.26 assigns correspondence of Group B Quality Standard to ASME Code Section III Class 2.23 Mandatory fracture toughness testing of ASME Code Section III Class 2 materials was first identified in the Summer 1977 Addenda Code Class 2 rules. As a result, cases exist where Class 2 ferritic materials of the reactor containment pressure boundary were not fracture toughness tested, because the ASME Code Edition and Addenda in effect at the time the components were ordered, did not require that they be tested. The staff's assessment of the fracture toughness of materials that were not fracture toughness tested is based on the metallurgical characterization of these materials and fracture toughness data presented in NUREG-0577, "Potential for Low Fracture Toughness and Lamellar Tearing on PWR Steam Generator and Reactor Coolant Pump Supports," USNRC, October 1979 (Draft)(Reference 6) and ASME Code Section III, Summer 24 1977 Addenda, Subsection NC. The metallurgical characterization of these materials, with respect to their fracture toughness, is developed from a review of how these materials were fabricated and what thermal history they experienced during fabrication. The metallurgical characterization of these materials, when correlated with the data presented in NUREG-0577 and the Summer 1977 Addenda of the ASME Code Section III, provides the technical basis for the staff's evaluation of the compliance with Code Class 2 requirements of the materials which were not fracture toughness tested. Technical Rationale:25 The technical rationale for application of the above acceptance criteria to fracture prevention of containments is discussed in the following paragraphs: 1. GDC 1 requires that systems be