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:
the break, but far from the break, the pressure variation is quite different, often peaking near the outer edges of the jet. Therefore, applying the standard’s formulas could lead to nonconservative pressures away from the jet centerline. Jet Dynamic Loading including Potential Feedback Amplification and Resonance Effects Furthermore, unsteadiness in free jets, especially supersonic jets, tends to propagate in the shear layer and induce time-varying oscillatory loads on obstacles in the flow path. Pressures and densities vary nonmonotonically with distance along the axis of a typical supersonic jet, feeding and interacting with shear layer unsteadiness. In addition, for a typical supersonic jet, interaction with obstructions will lead to backward-propagating transient shock and expansion waves that will cause further unsteadiness in downstream shear layers. Moreover, synchronization of the transient waves with the shear layer vortices emanating from the jet break can lead to significant amplification of the jet pressures and forces (a form of resonance) that is not considered in the ANSI/ANS 58.2 Standard. Should the dynamic response of the neighboring structure also synchronize with the jet loading time scales, further amplification of the loading can occur, including that at the source of the jet.2 Some general observations by past investigators are that strong discrete frequency loads are observed when the impingement surface is within 10 diameters of the jet opening, and that when resonance within the jet occurs, significant amplification of impingement loads can result3. Implications for NRC Staff Reviews Given that alternate standards are not yet available to address the topics described above, the staff reviews each new reactor design certification application concerning its dynamic jet load modeling on a case by case basis. 1 Knowledge Base for Emergency Core Cooling System Recirculation Reliability, February 1996, issued by the NEA/CSNI,