Document: 10 CFR Part 50
Document ID: ebc72932-4988-4c38-b485-e106d10d737c
Document Type: cfr
Title: Alternate 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-50.61a
Revision Date: 
Chapter: 
Section ID: 50.61a
CFR Part: 50
CFR Title: 10

Content:
he clad-to-base metal interface and three-eighths [ 2 ] of the vessel thickness exceed the size allowable in ASME Code, Section XI, Table IWB-3510-1. ( 5 ) The analyses required by paragraph (e)(4) of this section must address the effects on TWCF of the known sizes and locations of all flaws detected by the ASME Code, Section XI, Appendix VIII, Supplement 4 and Supplement 6 ultrasonic examination out to three-eights of the vessel thickness from the inner surface, and may also take into account other reactor vessel-specific information, including fracture toughness information. ( 6 ) For all flaw assessments performed in accordance with paragraph (e)(4) of this section, the licensee shall prepare and submit a neutron fluence map, projected to the date of license expiration, for the reactor vessel beltline clad-to-base metal interface and indexed in a manner that allows the determination of the neutron fluence at the location of the detected flaws. ( f ) Calculation of RT MAX-X values. Each licensee shall calculate RT MAX-X values for each reactor vessel beltline material using φt. The neutron flux (φ[t]), must be calculated using a methodology that has been benchmarked to experimental measurements and with quantified uncertainties and possible biases. [ 3 ] ( 1 ) The values of RT MAX-AW , RT MAX-PL , RT MAX-FO , and RT MAX-CW must be determined using Equations 1 through 4 of this section. When calculating RT MAX-AW using Equation 1, RT MAX-AW is the maximum value of (RT NDT(U) + ΔT 30 ) for the weld and for the adjoining plates. When calculating RT MAX-CW using Equation 4, RT MAX-CW is the maximum value of (RT NDT(U) + ΔT 30 ) for the circumferential weld and for the adjoining plates or forgings. ( 2 ) The values of ΔT 30 must be determined using Equations 5, 6 and 7 of this section, unless the conditions specified in paragraph (f)(6)(v) of this section are not met, for each axial weld, plate, forging, and circumferential weld. The ΔT 30 value for each axial