Document: NUREG-0800
Document ID: 89a50aec-b387-4999-9c8e-3b8e4f289a55
Document Type: srp
Title: Revision 3 - March 2007
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0708/ML070800027.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3
CFR Part: 
CFR Title: 

Content:
rotective structures as specified in A.2, pipe breaks should be postulated at the following locations in each piping or branch run within the confines of the structures or compartments that enclose or adjoin areas containing systems and components important to safety: a. the terminal ends9 of piping or branch run (except as exempted by A.4), if located within the boundary of the confining structure or each compartment within the structure; and b. any intermediate 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 + SA)8 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 BTP 3-3-18 Revision 3 - March 2007 length except that no intermediate locations 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.)