Document: NUREG-0800
Document ID: d8b522d4-dee5-4122-89d4-b2b45d0ca729
Document Type: srp
Title: REACTOR COOLANT PRESSURE BOUNDARY MATERIALS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070420.pdf
Revision Date: 2023-06
Chapter: 5
Section ID: 5.2.3
CFR Part: 
CFR Title: 

Content:
xamination are reviewed. 4. Fabrication and Processing of Austenitic Stainless Steel Austenitic stainless steels in a variety of product forms (including several stabilized product forms) are used for construction of pressure-retaining components in the reactor coolant pressure boundary. Unstabilized austenitic type stainless steels, which include American Iron and Steel Institute (AISI) Types 304 and 316, are normallyfrequently used. Because these compositions are susceptible to stress corrosion cracking when 16 exposed to certain environmental conditions, process controls must be exercised during all stages of component manufacturing and reactor construction to avoid severe sensitization of the material and to minimize exposure of the stainless steel to contaminants that could lead to stress corrosion cracking. Items 4.a, 4.b, 4.d, and 4.e are reviewed by MTEB; and item 4.c is reviewed I by CMEB. Upon request the CMEB will review corrosion testing data.17 a. Sensitization is caused by intergranular precipitation of chromium carbide in austenitic stainless steels that are exposed to temperatures in the approximate DRAFT Rev. 3 - April 1996 5.2.3-4 range of 430 C to 820 C (800 F to 1500 F) . Precipitation of the chromium 18 carbide at the grain boundaries increases with increasing carbon content and exposure time. Control of the application and processing of stainless steel is needed to eliminate the occurrences of stress corrosion cracking in sensitized stainless steel components of nuclear reactors. Test data and service experience demonstrate that sensitized stainless steel is significantly more susceptible to stress corrosion cracking than nonsensitized (solution heat treated) stainless steel. The following areas are reviewed: requirements for solution heat treatment of stainless steel; plans to avoid partial or severe sensitization during welding, including information on welding methods, heat input, and interpass temperatures; and a description of the material