Document: NUREG-0800
Document ID: 8afa51d9-10c9-4521-a19c-f082a562bcda
Document Type: srp
Title: -
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1602/ML16029A367.pdf
Revision Date: 2023-06
Chapter: 5
Section ID: 5.4.2.1
CFR Part: 
CFR Title: 

Content:
ction program. Rapid and unpredictable degradation includes degradation mechanisms that result from excitation mechanisms, such as fluid-elastic instability. For fatigue, the steam generator tubes and tube-to-tubesheet welds are considered acceptable if they comply with RG 1.207, “Guidelines for Evaluating Fatigue Analyses Incorporating the Life Reduction of Metal Components Due to the Effects of the Light-Water Reactor Environment for New Reactors.” However, acceptable fatigue design does not ensure fluid-elastic instability has been addressed. For degradation mechanisms resulting from a phenomenon such as fluid-elastic instability, the steam generator design and fabrication details should be reviewed on a case-by-case basis as outlined below. 5.4.2.1-8 Draft Revision 4 – April 2016 For a degradation mechanism review of a steam generator design that is similar to existing designs, the reviewer should: Confirm that the thermal-hydraulic and flow-induced vibration analyses used modeling software that has been used in nuclear steam generator designs and has resulted in successful steam generator operation, or was benchmarked successfully against such software. The effectiveness of anti-vibration bars at preventing fluid-elastic instability should be considered in the analyses. 1. Confirm that the most limiting location in the tube bundle was evaluated and that the analyses accounted for tube plugging and tube bundle fouling. 2. Confirm that for analyses of the steam generator tubes, the flow-induced vibration model shows that sufficient margin to fluid-elastic instability (i.e., at least 25 percent) has been maintained. If conditions 1 – 3 are not met, or if the steam generator design is new or unique, a detailed evaluation of the technical basis should be performed. The detailed evaluation may include reviewing scale testing under the expected operating conditions. B. Limits the crevice between the tube and the tube supports. This can be accomplished by using