Document: NUREG-0800
Document ID: b6b57a00-5b85-4f0c-965c-ca89ef4265e7
Document Type: srp
Title: DETERMINATION OF RUPTURE LOCATIONS AND DYNAMIC EFFECTS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1608/ML16088A041.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.6.2
CFR Part: 
CFR Title: 

Content:
ural response. iii. The time variation of the jet thrust forcing function should be related to the pressure, enthalpy, and volume of fluid in the upstream reservoir and the capability of the reservoir to supply a high energy flow stream to the break area for a significant interval. The shape of the transient function may be modified by considering the break area and the system flow conditions, the piping friction losses, the flow directional changes, and the application of flow-limiting devices. iv. The jet thrust force may be represented by a steady state function if the energy balance model or the static model is used in the subsequent pipe motion analysis. In either case, a step function amplified as indicated in Subsection III.5.B(ii) or III.5.B(iii), above, is acceptable. The function should 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. 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 3.6.2-11 Revision 3 – December 2016 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