Document: 10 CFR Part 50
Document ID: a6c1b81f-bcf5-4ef9-9e8b-2a055aaed0aa
Document Type: cfr
Title: Fracture toughness requirements for protection against pressurized thermal shock events.
Source: 10 CFR Part 50
Source URL: https://www.ecfr.gov/current/title-10/part-50/section-50.61
Revision Date: 
Chapter: 
Section ID: 50.61
CFR Part: 50
CFR Title: 10

Content:
beltline material, including the assumptions regarding core loading patterns, and must specify the copper and nickel contents and the fluence value used in the calculation for each beltline material. This assessment must be updated whenever there is a significant [ 2 ] change in projected values of RT PTS , or upon request for a change in the expiration date for operation of the facility. ( 2 ) The pressurized thermal shock (PTS) screening criterion is 270 °F for plates, forgings, and axial weld materials, and 300 °F for circumferential weld materials. For the purpose of comparison with this criterion, the value of RT PTS for the reactor vessel must be evaluated according to the procedures of paragraph (c) of this section, for each weld and plate, or forging, in the reactor vessel beltline. RT PTS must be determined for each vessel beltline material using the EOL fluence for that material. ( 3 ) For each pressurized water nuclear power reactor for which the value of RT PTS for any material in the beltline is projected to exceed the PTS screening criterion using the EOL fluence, the licensee shall implement those flux reduction programs that are reasonably practicable to avoid exceeding the PTS screening criterion set forth in paragraph (b)(2) of this section. The schedule for implementation of flux reduction measures may take into account the schedule for submittal and anticipated approval by the Director, Office of Nuclear Reactor Regulation, of detailed plant-specific analyses, submitted to demonstrate acceptable risk with RT PTS above the screening limit due to plant modifications, new information or new analysis techniques. ( 4 ) For each pressurized water nuclear power reactor for which the analysis required by paragraph (b)(3) of this section indicates that no reasonably practicable flux reduction program will prevent RT PTS from exceeding the PTS screening criterion using the EOL fluence, the licensee shall submit a safety analysis to determine what, if