Document: NUREG-0800
Document ID: e89cc26c-d19a-42b8-818a-fb598c05ccee
Document Type: srp
Title: PLANT DESIGN FOR PROTECTION AGAINST POSTULATED PIPING FAILURES IN FLUID
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340548.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.6.1
CFR Part: 
CFR Title: 

Content:
location within the boundary of the confining structure or each compartment within the structure where the stresses5 under the loadings associated with specified seismic events6 and operational plant conditions7 exceed 0.8 (Sh + S de or, in lieu of these calculated stress-related locations, at each fitting (i.e., elbow, tree, cross, non-standard fitting); and c. a minimum of two separated locations within the boundary of the confining structure of each compartment within the structure in piping or branch runs exceeding twenty pipe diameters in length; a minimum of one location in piping or branch runs twenty pipe- diameters or less in length except that no intermediate locations 3.6.1-25 Rev. 2 - October 1990 need to be postulated in branch runs that are three pipe-diameters or less in length. Intermediate break locations should be selected such that the maximum pipe whip and jet impingement will result, assuming for this purpose an unrestrained ruptured pipe. 4. For those portions of the piping passing through primary containment penetrations and extending to the first outside isolation valve, pipe breaks need not be postulated provided such piping is conservatively reinforced and restrained beyond the valve such that, in the event of a postulated pipe break outside containment, the transmitted pipe loads will neither impair the operability of the valve nor the integrity of the piping or the containment penetration. (A terminal end of such piping is considered to originate at this restraint location.) B. Moderate-Energy Fluid Systems 1. For piping systems that by plant arrangement and layout are isolated and physically separated and remotely located from systems and compo- nents important to safety, through-wall leakage cracks need not be postulated. 2. For piping systems that are located in the same areas as high-energy fluid systems which, by the criteria of A.1 to A.3 have postulated pipe break locations, through-wall leakage cracks need not be postulated. 3.