Document: NUREG-0800
Document ID: 38291c4d-6d61-4922-8b44-6af61374cfaa
Document Type: srp
Title: ENGINEERED SAFETY FEATURES MATERIALS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340646.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.1.1
CFR Part: 
CFR Title: 

Content:
oncentration of hydrogen in the containment atmosphere following postulated accidents is controlled to maintain containment integrity, the hydrogen generation resulting from the corrosion of metals by the containment sprays during design basis accident should be controlled as described in Regulatory Guide 1.7, "Control of Combustible Gas Concentrations in Containment Following a Loss-of-Coolant Accident." a. Pressurized Water Reactors (PWRs) To meet the requirement of GDC 4, 14, and 41, the composition of containment spray and core cooling water should be controlled to ensure a minimum pH of 7.0 as given in Branch Technical Posi- tion MTEB 6-1 which is appended to this SRP section. Experience has shown that maintaining the pH of borated solutions at this level will help to inhibit initiation of stress corrosion cracking of austenitic stainless steel components. The hydrogen generation from the corrosion of materials within containment, such as aluminum and zinc, depends upon the corro- sion rate which in turn depends upon such factors as the coolant chemistry, the coolant pH, the metal and coolant temperature, and the surface area exposed to attack by the coolant. The reviewer compares the assumed corrosion rates of materials in containment with standard corrosion rate data. b. Boiling Water Reactors (BWRs) To meet the requirements of GDC 4, 14, and 41, the water used in the engineered safety feature systems should be controlled to provide assurance against stress corrosion cracking of unstabilized austenitic stainless steel components. Water used for emergency core cooling systems and spray systems should be controlled to ensure the following limits: Conductivity = 3 to 10 phos/cm @ 25?C Chloride (Cl-) < 0.50 ppm pH = 5.3 to 8.6 @ 25VC Hydrogen generation in BWR containments is assumed to follow the same characteristics as in PWRs in that the rates of hydrogen generation will rise with increasing zinc corrosion as the temperature rises, and will change with any