Document: NUREG-0800
Document ID: 0e333e1a-276a-43f1-b2ab-fdf1009c6f92
Document Type: srp
Title: Draft Revision 3 – August 2015
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1422/ML14227A646.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3
CFR Part: 
CFR Title: 

Content:
Systems Qualifying as High-Energy or Moderate-Energy Systems. Through-wall leakage cracks instead of breaks may be postulated in the piping of those fluid systems12 that qualify as high-energy fluid systems for only a short operational period but qualify as moderate-energy fluid systems for the major operational period. 3. Type of Breaks and Leakage Cracks in Fluid System Piping (i) Circumferential Pipe Breaks The following circumferential breaks should be postulated individually in high- energy fluid system piping at the locations specified in 2.A of this BTP: (1) Circumferential breaks should be postulated in fluid system piping and branch runs exceeding a nominal pipe size of 1 inch, except where the maximum stress range13 exceeds the limits specified in 2.A(iii)(1) and 2A(iii)(2), and the circumferential stress range is at least 1.5 times the axial stress range. Instrument lines, as well as 1 inch and less nominal pipe or tubing size, should meet the provisions of Regulatory Guide (RG) 1.11, “Instrument Lines Penetrating Primary Reactor Containment (Safety Guide 11).” (2) Where break locations are selected without the benefit of stress calculations, breaks should be postulated at the piping welds to each fitting, valve, or welded attachment. (3) Circumferential breaks should be assumed to result in pipe severance and separation amounting to at least a one-diameter lateral displacement of the ruptured piping sections unless physically limited by piping restraints, structural members, or piping stiffness as may be demonstrated by inelastic limit analysis (e.g., a plastic hinge in the piping is not developed under loading). (4) The dynamic force of the jet discharge at the break location should be based on the effective cross-sectional flow area of the pipe and on a calculated fluid pressure as modified by an analytically or experimentally determined thrust coefficient. Limited pipe displacement at the break location, line restrictions, flow limiters,