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:
nd 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 weld calculated as specified by Equation 1 of this section must be calculated for the maximum fluence (φt AXIAL-WELD ) occurring along a particular axial weld at the clad-to-base metal interface. The ΔT 30 value for each plate calculated as specified by Equation 1 of this section must also be calculated using the same value of φt AXIAL-WELD used for the axial weld. The ΔT 30 values in Equation 1 shall be calculated for the weld itself and each adjoining plate. The ΔT 30 value for each plate or forging calculated as specified by Equations 2 and 3 of this section must be calculated for the maximum fluence (φt MAX ) occurring at the clad-to-base metal interface over the entire area of each plate or forging. In Equation 4, the fluence (φt WELD-CIRC ) value used for calculating the plate, forging, and circumferential weld ΔT 30 value is the maximum fluence occurring for each material along the circumferential weld at the clad-to-base metal interface. The ΔT 30 values in Equation 4 shall be calculated for the circumferential weld and for the adjoining plates or forgings. If the conditions specified in paragraph (f)(6)(v) of this section are not met, licensees must propose ΔT 30 and RT MAX-X values in accordance with paragraph (f)(6)(vi) of this section. ( 3 ) The values of Cu, Mn, P, and Ni in Equations 6 and 7 of this section must represent the best estimate values for the material. For a plate or forging, the best estimate value is normally the mean of the measured values for that plate or forging. For a weld, the best estimate value is normally the mean of the measured values for a weld deposit made using the same weld wire heat number as the critical vessel weld. If these values are not available, either the upper limiting values given in the material