Document: NRC Regulatory Guide
Document ID: ad61f8a3-1cce-4446-9542-dcdda55c1ec6
Document Type: regulatory_guide
Title: Comprehensive Vibration Assessment Program for Reactor Internals During Preoperational and Initial Startup Testing + HISTORY - HISTORY 07/2015 – DG-1323 , Proposed Revision 4 03/2013 – Periodic Review of Revision 3 – No Issues Identified 11/2006 – DG-1163 , Proposed Revision 3 (Rev. 4)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1508/ML15083A390.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.20
CFR Part: 
CFR Title: 

Content:
ge 5 licensed under 10 CFR Part 52. For example, ITAAC for reactor internals in a BWR nuclear power plant may include the following: • Reactor internal structures meet American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (BPV) Code, Section III, “Nuclear Power Plant Components,” Subsection NG- 3000 (Ref. 4), as incorporated by reference in 10 CFR 50.55a. [The applicant may propose relaxed weld quality factors for secondary welds in BWR steam dryers where justified.] • The set of as-built BWR steam dryer instrumentation includes an adequate number of pressure sensors, strain gages, and accelerometers to apply the steam dryer analysis program based on startup test data. • The design and construction of MSL branch lines and safety/relief valve and safety valve standpipe geometry in BWR nuclear power plants will preclude first and second shear layer wave acoustic resonances. • Maximum calculated alternating stress intensity for a BWR steam dryer at the detailed design stage provides a margin of safety compared to the ASME BPV Code limit in Subsection NG. The acceptable margin of safety will be established as part of the application review based on the design and analysis details. In addition, the NRC staff has imposed license conditions to address BWR steam dryer monitoring during and after plant startup. “Reactor internals,” as used in this regulatory guide, consist of core support structures and adjoining internal structures inside the RPV. Specifically, those core support and internal structures are defined in Article NG-1120 of Section III, of the ASME BPV Code. For example, for BWR nuclear power plants, reactor internals might include the following components: • chimney and partitions • chimney head and steam separator assembly • steam dryer assembly • feedwater spargers • standby liquid control header and spargers and piping • RPV vent assembly • core plate • top guide • control rod drive housing and guide