Document: NUREG-0800
Document ID: c6f58bab-ddce-42eb-a3ef-02dd3da952fc
Document Type: srp
Title: Revision 3 – December 2016
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1608/ML16085A315.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3
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lative usage factor exceeds 0.1. For new reactor design certification reviews, the staff has considered a CUF limit of 0.4 to be acceptable when the effects of EAF are considered in the piping design. As a result of piping reanalysis, the highest stress locations may be shifted; however, the initially determined intermediate break locations need not be changed unless one of the following conditions exists: (i) The dynamic effects from the new (as-built) intermediate break locations are not mitigated by the original pipe-whip restraints and jet shields. (ii) A change is necessary in pipe parameters such as major differences in pipe size, wall thickness, and routing. 3 This term is defined as the extremities of piping runs that connect to structures, components (e.g., vessels, pumps, valves), or pipe anchors that act as rigid constraints to piping motion and thermal expansion. A branch connection to a main piping run is a terminal end of the branch run, except where the branch run is classified as part of a main run in the stress analysis and is shown to have a significant effect on the main run behavior. In piping runs that are maintained pressurized during normal plant conditions for only a portion of the run (i.e., up to the first normally closed valve), a terminal end of such a run is the piping connection to this closed valve. 4 See Footnote 2. BTP 3-4-6 Revision 3 –December 2016 (2) With the exceptions of those portions of piping identified in 2A(ii), breaks in Class 2 and 3 piping (ASME Code, Section III) should be postulated at the following locations in those portions of each piping and branch run: (a) At terminal ends. (b) At intermediate locations selected by one of the following criteria: (i) At each pipe fitting (e.g., elbow, tee, cross, flange, and nonstandard fitting), welded attachment, and valve. Or, where the piping contains no fittings, welded attachments, or valves, at one location at each extreme of the piping run adjacent to the protective