Document: NUREG-0800
Document ID: b8d2b8f5-432a-4c0a-81ab-20231f7d0f28
Document Type: srp
Title: PROBABILISTIC RISK ASSESSMENT AND SEVERE ACCIDENT EVALUATION FOR
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1508/ML15089A068.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.0
CFR Part: 
CFR Title: 

Content:
32. The seismic demands to equipment defined in terms of the required response spectra should use CSDRS-based (or hard rock high frequency, if applicable) seismic input and account for the structural amplifications caused by the supporting structures, including soil-structure interaction effects and supporting systems, and incorporate an additional seismic margin factor, as appropriate. 33. The HCLPF value for an SSC is earthquake motion level at which there is a high (95%) confidence of a low (at most 5%) probability of failure. The composite uncertainty (Beta c) may be used to approximate the HCLPF, which would be the ground motion level at which the composite probability of failure is at most 1%. 34. The HCLPF value should be expressed in terms of PGA in the PRA-based SMA process. 35. The plant-level HCLPF capacity should be determined based on the sequence-level HCLPF values for all sequences as identified in the design-specific plant system and accident sequence analysis. 36. The Min-Max method4 is acceptable for computing sequence-level HCLPF values. 37. The staff will determine whether the design-specific plant-level HCLPF value has been demonstrated to be equal to or greater than 1.67 times the CSDRS PGA. III. REVIEW PROCEDURES General Principles The reviewer will select material from the procedures described below, as may be appropriate for a particular case. These review procedures are based on the identified SRP acceptance criteria. If the application deviates from these acceptance criteria, the staff should determine 4 A Min-Max method is used to determine the HCLPF capacity for an accident sequence from the HCLPF capacities of the contributing SSC failures, or the HCLPF capacity for the plant as a whole from the HCLPF capacities of the group of seismic- initiated accident sequences. The overall HCLPF capacity of two or more SSCs that contribute to a sequence using OR Boolean logic is equal to the lowest individual HCLPF capacity of the constituents of