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:
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 underclad cracks have been detected and that were fabricated in accordance with Regulatory Guide 1.43. 8 RT PTS limits contribute 1 × 10 −8 per reactor year to the reactor vessel TWCF. 9 Forgings with underclad cracks apply to forgings that have detected underclad cracking or were not fabricated in accordance with Regulatory Guide 1.43. Table 2—Allowable Number of Flaws in Welds Through-wall extent, TWE [in.] Maximum number of flaws per 1,000-inches of weld length in the inspection volume that are greater than or equal to TWE MIN and less than TWE MAX TWE MIN TWE MAX 0 0.075 No Limit. 0.075 0.475 166.70. 0.125 0.475 90.80. 0.175 0.475 22.82. 0.225 0.475 8.66. 0.275 0.475 4.01. 0.325 0.475 3.01. 0.375 0.475 1.49. 0.425 0.475 1.00. 0.475 Infinite 0.00. Table 3—Allowable Number of Flaws in Plates and Forgings Through-wall extent, TWE [in.] Maximum number of flaws per 1,000 square-inches of inside surface area in the inspection volume that are greater than or equal to TWE MIN and less than TWE MAX . This flaw density does not include underclad cracks in forgings TWE MIN TWE MAX 0 0.075 No Limit. 0.075 0.375 8.05. 0.125 0.375 3.15. 0.175 0.375 0.85. 0.225 0.375 0.29. 0.275 0.375 0.08. 0.325 0.375 0.01. 0.375 Infinite 0.00. Table 4—Conservative Estimates for Chemical Element Weight Percentages Materials P Mn Plates 0.014 1.45 Forgings 0.016 1.11 Welds 0.019 1.63 Table 5—Maximum Heat-Average Residual [ °F] for Relevant Material Groups by Number of Available Data Points (Significance Level = 1%) Material group σ [ °F] Number of available data points 3 4 5 6 7 8 Welds, for Cu >0.072 26.4 35.5 30.8 27.5 25.1 23.2 21.7 Plates, for Cu >0.072 21.2 28.5 24.7 22.1 20.2 18.7 17.5 Forgings, for Cu >0.072 19.6 26.4 22.8 20.4 18.6 17.3 16.1 Weld, Plate or Forging, for Cu