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:
ems should be equivalent to the following: (a) ASME Section III Code Class I piping2 breaks should be postulated to occur at the following locations in each piping run3 or branch run: (1) The terminal ends; (2) And intermediate locations between terminal ends where the primary plus secondary stress intensities S (circumferential or longitudinal) derived on an elastically calculated basis under the loadings associated with one-half safe shutdown earthquake and operational plant conditions4 exceeds 2.0 S 5 for ferritic steel, and 2.4 S for austenitic steel; m (3) Any intermediate locations between terminal ends where the cumulative usage factor (U)6 derived from the piping fatigue analysis and based on all normal, upset, and testing plant conditions exceeds 0.1; and (4) At intermediate locations in addition to those determined by (1) and (2) above, selected on a reasonable basis as necessary to provide protection. As a minimum, there should be two intermediate locations for each piping run or branch run. (b) ASME Section III Code Class 2 and 3 piping breaks should be postulated to occur at the following locations in each piping run or branch run: (1) The terminal ends; (2) Any intermediate locations between terminal ends where either the circumferential or longitudinal stresses derived on an elastically calculated basis under the loadings associated with seismic events and operational plant conditions exceed 0.8 (Sb + SA)7 or the expansion stresses exceed 0.8 SA; and (3) Intermediate locations in addition to these determined by (2) above, selected on a reasonable basis as necessary to provide protection. As a minimum, there should be two intermediate locations for each piping run or branch run. 3.6.1-17 Rev. 2 - October 1990 3. The criteria used to determine the pipe break orientation at the break locations as specified under (2) above should be equivalent to the following: (a) Longitudinal 8 breaks in piping runs and branch runs, 4 :%.ches nominal pipe size and