Document: NRC Regulatory Guide
Document ID: bbd6ed7f-058c-4bd2-8849-f708d0179bbf
Document Type: regulatory_guide
Title: Flexible Mitigation Strategies for Beyond-Design-Basis Events + HISTORY - HISTORY 11/2015 – DG-1301 , Proposed Revision 0
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1316/ML13168A031.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.226
CFR Part: 
CFR Title: 

Content:
for reasonable protection as follows: a. Qualitatively based on Seismic Experience. EPRI NP-6041-SL and EPRI TR- 104871, “Generic Seismic Technical Evaluations of Replacement Items for Nuclear Power Plants,” (Ref. 40) provide guidance on rugged SSCs. Such equipment that was not included within the ESEP review and that have high seismic capacities would require no further actions to demonstrate reasonable assurance to withstand the new seismic hazard. These SSCs include: 1. Piping, cabling, conduit, and their supports 2. Manual valves, check valves, and rupture disks DG-1301, Page 18 3. Power operated valves not required to change state as part of the FLEX mitigation strategies 4. Nuclear steam supply system components (e.g. reactor pressure vessel and internals, control rod drive mechanisms (CRDMs), fuel rods, reactor coolant pumps and seals, etc.) 5. Portable FLEX equipment (tie downs and seismic interactions should be addressed using the approach 3 below) 6. Safety-related buildings b. Quantitatively as described in item c below for SSCs and seismic interactions that were not included in the ESEP review and cannot be justified to be inherently rugged for seismic accelerations and displacements. Examples of these SSCs and seismic interactions include: 1. Haul Path – including liquefaction, slope stability and interactions 2. FLEX Equipment Storage Building and Non-Seismic Category 1 Structures 3. Operator Pathways – interaction pathway review, use the beyond-design- basis seismic evaluation criteria described in § 6.1.2.2.1.c, below, if calculation is required 4. Tie down of FLEX portable equipment that are required to be restrained during the earthquake c. Beyond-Design-Basis Seismic Evaluation Criteria In order to demonstrate reasonable protection of equipment that was not included in the ESEP review and is not inherently rugged for seismic accelerations, a licensee should demonstrate that the GMRS level of seismic hazard at the site results in an