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:
pply to fragilities tied to ground motion parameters (e.g., PGA or Peak Spectral Acceleration at 5 Hz). The ratios of the 10% failure probability capacity C10% to the C1% capacity have been calculated and are shown in the last column of Table 1. The method for demonstrating the adequate seismic ruggedness for mitigation systems would follow the approach for an SMA wherein a defined capacity is shown to exceed the defined demand. In the case of an SMA the demand for the assessment is referred to as the review level earthquake (RLE). The following steps would be undertaken for SSCs within the mitigation systems that undertake the C10% review: • The GMRS will be the RLE for the beyond-design-basis seismic review of the mitigation strategies • The seismic capacity aligned with reasonable protection will be the C10% value. The C10% can be calculated by: o Calculate the C1% capacity using the methods documented in past SPRA and seismic margin documentation and as summarized in the SPID defined in EPRI 1025287. o Multiply the C1% capacity by the C10%/C1% ratio from Table 1 based on the type of SSC being evaluated • Verify that the C10% capacity exceeds the RLE demand Table 1: βC, βR, βU, and C50%/C1% Values for Hybrid Method for Various Types of SSCs Type SSC Composite βC Random βR Uncertainty βU C50%/C1% C10%/C1% Structures & Major Passive Mechanical Components Mounted on Ground or at Low Elevation Within Structures 0.35 0.24 0.26 2.26 1.44 Active Components Mounted at High Elevation in Structures 0.45 0.24 0.38 2.85 1.60 Other SSCs 0.40 0.24 0.32 2.54 1.52 DG-1301, Page 20 2. Licensees relying on the ESEP to demonstrate reasonable protection of equipment necessary to maintain or restore core cooling and containment capabilities should: a. Evaluate the seismic capacity of equipment necessary to maintain or restore SFP cooling capabilities to the GMRS for the reevaluated seismic hazard; and b. Evaluate HF sensitive in-plant SSCs relied upon to maintain or