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
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Content:
itted. Such an approach may be acceptable if conservative assumptions are used such that it is reasonable to conclude that the results bound those expected with the more detailed approach described in NUREG/CR-6850 with respect to CDF and LRF. Examples of conservative assumptions that have been accepted by the staff in previous reviews are listed below: A. Fire ignition in any fire area continues to grow unchecked into a fully developed fire without credit for fire suppression and causes the maximum possible damage to SSCs in the area. B. Bounding fire initiating event frequencies are applied. C. No credit is taken for the distance between fire sources and targets. D. All fire-induced equipment damage occurs at the beginning of the event. E. Any fire in the switchyard is assumed to result in a reactor trip. F. Although design features have been implemented to prevent spurious actuations induced by a single fire in a building, the PRA should assume that fire propagation in the building may lead to spurious actuation of equipment that could cause initiating events or prevent mitigating systems from operating properly. 2. The reviewer confirms that the fire risk analysis uses the same systems and accident sequence models as the internal events evaluation. 19.0-26 Revision 3 – December 2015 3. The reviewer confirms that the applicant has determined the appropriate internal event sequences based on the specific fire location and correctly modified these sequences to consider the effects of specific fires and include the possibility of fire propagation through potentially failed fire barriers. 4. The reviewer confirms that the applicant reports the CDF and LRF derived from the fire PRA in the FSAR and provides a characterization of the dominant accident sequences and associated major contributors to CDF for each sequence in the FSAR. Design-Specific PRA (Treatment of High Winds) The NRC staff reviews the findings of the peer review to Part 7 of the ASME/ANS PRA