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:
le Protection for Exceedances Limited to High Frequency Staff Position: If the ground motion response spectrum (GMRS) for a licensee’s reevaluated seismic hazard is fully bounded by the licensee’s design basis seismic hazard from 1 Hz to 10 Hz, but exceeds the design basis seismic hazard above 10 Hz, the licensee should evaluate high frequency (HF) sensitive in-plant SSCs relied upon for execution of the mitigating strategies using the methodologies of the EPRI Report 3002004396, “High Frequency Program: Application Guidance for Functional Confirmation and Fragility Evaluation,” (Ref. 27) consistent with its endorsement by letter dated September 17, 2015, (Ref. 28). 6.1.2. Alternate Mitigating Strategies Staff Position: Development of an Alternate Mitigating Strategy (AMS) that provides a capability to mitigate the BDBEE by mitigating or preventing an ELAP that would occur as a result of the BDBEE through exhaustion of fuel for operating emergency power sources is an acceptable method of compliance with 10 CFR 50.155(b)(1) when the hazard level for the AMS is identified. a. Reevaluated seismic hazard should be used in place of the safe shutdown earthquake (SSE) as described in Section 6.1 of this RG. b. The initial condition of NEI 12-06, Rev. 1A, Section 3.2.1.3.1 should be modified to reflect the reevaluated seismic hazard as the initiating event for the associated AMS. Timing of the loss of off-site power should reflect impact of the flooding mechanism on the delivery of off-site power to the facility. DG-1301, Page 16 c. The initial condition of NEI 12-06, Rev. 1A, Section 3.2.1.3.2 should be modified to reflect the availability of emergency on-site ac power sources and station blackout alternate ac power sources unless and until they are rendered unavailable by the reevaluated seismic hazard. 6.1.2.1. Case 1: Demonstration of Reasonable Protection Based upon the Individual Plant Examination of External Events Licensees completed the Individual Plant