Document: NUREG-0800
Document ID: 92d817ac-3ce3-4cf7-8d1a-627e8242fbf2
Document Type: srp
Title: PLANT DESIGN FOR PROTECTION AGAINST POSTULATED PIPING FAILURES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070312.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.6.1
CFR Part: 
CFR Title: 

Content:
eria of A.1 to A.3 have postulated pipe break locations, through-wall leakage cracks need not be postulated. 3. For piping systems that are located in areas containing systems and components important to safety, but where no high-energy fluid systems are present, through-wall leakage cracks should be postulated at the most adverse location to determine the protection needed to withstand the effects of the resulting water spray and flooding. C. Side and Types of Pipe Breaks and Cracks 1. The following types of breaks should be postulated at the locations specified by the criteria listed under A. High-Energy Fluid Systems: a. longitudinal breaks in piping runs and branch runs with nominal pipe sizes of 10 cm (4 inches) and larger, 54 b. circumferential breaks in piping runs and branch runs exceeding a nominal pipe size of 2.5 cm (1 inch).55 DRAFT Rev. 3 - April 1996 3.6.1-30 2. The following leakage cracks are postulated at the locations specified by the criteria listed under B, Moderate-Energy Fluid Systems: a. through-wall leakage cracks in piping and branch runs exceeding a nominal pipe size of 2.5 cm (1 inch), where the crack opening is 56 assumed as 1/2 the pipe diameter in length and 1/2 the pipe wall thickness in width. FOOTNOTES High-energy systems include those systems where either of the following conditions are 1a. met: (a) the maximum operating temperature exceeds 95 C (200 F), and 57 (b) the maximum operating pressure exceeds 1900 kPa (275 psig).58 Moderate energy systems include those systems where both of the following conditions 2b. are met: (a) the maximum operating temperature is 95 C (200 F) or less, and 59 (b) the maximum operating pressure is 1900 kPa (275 psig) or less. 60 These criteria are intended for the purpose of designing piping restraints and do not c. preclude consideration of other aspects of the NRC General Design Criteria, such as single failure criteria and other additional protective measures required to provide protection against