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:
for φ <4.39 × 10 10 n/cm 2 /sec Where: φ [n/cm 2 /sec] = average neutron flux t [sec] = time that the reactor has been in full power operation φt [n/cm 2 ] = φ × t f(Cu e ,P) = 0 for Cu ≤0.072 f(Cu e ,P) = [Cu e −0.072] 0.668 for Cu >0.072 and P ≤0.008 f(Cu e ,P) = [Cu e −0.072 + 1.359 × (P−0.008)] 0.668 for Cu >0.072 and P >0.008 Where: Cu e = 0 for Cu ≤0.072 Cu e = MIN (Cu, maximum Cu e ) for Cu >0.072 maximum Cu e = 0.243 for Linde 80 welds maximum Cu e = 0.301 for all other materials g(Cu e ,Ni,φt e ) = 0.5 + (0.5 × tanh {[log 10 (φt e ) + (1.1390 × Cu e )−(0.448 × Ni)−18.120]/0.629} Equation 8: Residual (r) = measured ΔT 30 −predicted ΔT 30 (by Equations 5, 6 and 7) Equation 10: Maximum credible heat-average residual = 2.33σ/n 0.5 Where: n = number of surveillance data points (sample size) in the specific data set σ = standard deviation of the residuals about the model for a relevant material group given in Table 5. Where: m is the slope of a plot of all of the r values (estimated using Equation 8) versus the base 10 logarithm of the neutron fluence for each r value. The slope shall be estimated using the method of least squares. se(m) is the least squares estimate of the standard-error associated with the estimated slope value m. Where: r is defined using Equation 8 and σ is given in Table 5 Table 1—PTS Screening Criteria Product form and RT MAX-X values RT MAX-X limits [ °F] for different vessel wall thicknesses 6 (T WALL ) T WALL ≤9.5 in. 9.5 in. <T WALL ≤10.5 in. 10.5 in. <T WALL ≤11.5 in. Axial Weld—RT MAX-AW 269 230 222 Plate—RT MAX-PL 356 305 293 Forging without underclad cracks—RT MAX-FO 7 356 305 293 Axial Weld and Plate—RT MAX-AW + RT MAX-PL 538 476 445 Circumferential Weld—RT MAX-CW 8 312 277 269 Forging with underclad cracks—RT MAX-FO 9 246 241 239 6 Wall thickness is the beltline wall thickness including the clad thickness. 7 Forgings without underclad cracks apply to forgings for which no