Document: NUREG-0800
Document ID: 63f62189-691f-402d-9ac9-41fb60ec2261
Document Type: srp
Title: DETERMINATION OF RUPTURE LOCATIONS AND DYNAMIC EFFECTS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1423/ML14230A035.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.6.2
CFR Part: 
CFR Title: 

Content:
hould have a magnitude not less than T = KpA where p = system pressure prior to pipe break, A = pipe break area, and K = thrust coefficient. To be acceptable, K values should not be less than 1.26 for steam, saturated water, or steam-water mixtures or 2.0 for subcooled, nonflashing water. 3.6.2-11 Draft Revision 3 – August 2015 5. The following assumptions in modeling jet impingement forces are consistent, in part, with the guidance in the American National Standard Institute (ANSI)/American Nuclear Society (ANS) Standard 58.2-1988 currently used by industry. The ANSI/ANS 58.2 Standard has been accepted by the NRC. However, based on recent comments from the Advisory Committee on Reactor Safeguards (ACRS), it appears that some assumptions related to jet expansion modeling in the ANSI/ANS 58.2 Standard may lead to nonconservative assessments of the jet impingement loads of postulated pipe breaks on neighboring SSCs. The NRC staff is currently assessing the technical adequacy of the information pertaining to dynamic analyses models for jet thrust force and jet impingement load that are included in this SRP Section and ANSI/ANS 58.2. Pending completion of this effort, the NRC staff will review analyses of the jet impingement forces on a case by case basis. These analyses should show that jet impingement loadings on nearby safety related SSCs will not impair or preclude their essential functions. More details related to the potential nonconservatism of ANSI/ANS 58.2 Standard issue are discussed in Appendix A of this SRP. The assumptions are as follows: A. The jet area expands uniformly at a half angle, not exceeding 10 degrees. B. The impinging jet proceeds along a straight path. C. The total impingement force acting on any cross-sectional area of the jet is time and distance invariant, with a total magnitude equivalent to the jet thrust force as defined in Subsection III.5.C(iv), above. D. The impingement force is uniformly distributed across the cross-sectional area