Document: NUREG-0800
Document ID: dd4f84a9-8976-44c4-b631-d7c0254f4efc
Document Type: srp
Title: PROBABILISTIC RISK ASSESSMENT AND SEVERE ACCIDENT EVALUATION FOR
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1416/ML14161A594.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.0
CFR Part: 
CFR Title: 

Content:
A numerical changes should be reported when the cumulative risk impact of the changes resulting from the plant modifications, design changes or departures from the DC is more than a 10% change (either positive or negative) in the total CDF or total LRF from what was previously reported. B. All changes in key assumptions per RG 1.200 and all changes in risk insights as defined in RG 1.206 including differences between the updated risk insights and the certified design risk insights should also be reported to the NRC in accordance with the guidance in Section C.III of RG 1.206. C. All changes or departures from the design that result in a revision of PRA-based qualitative results should also be reported to the NRC. 19. 10 CFR 50.71(h)(2) states that each COL holder must maintain and upgrade the PRA required by 10 CFR 50.71(h)(1). This means that COL holders, in accordance with 10 CFR 50.71(h), must upgrade the PRA used to support the COL to cover those initiating events and modes of operation contained in NRC-endorsed consensus standards that exist one year prior to each required upgrade. The ASME PRA Standard describes “PRA upgrade” as the incorporation into a PRA model of a new methodology or significant changes in the scope or capability. This could include items such as new human error analysis methodology, new data, updated methods, new approaches to quantification or truncation, or new treatment of CCF. 20. RG 1.200 describes the elements of a PRA maintenance and update program that is acceptable to the staff. If the staff can confirm that the applicant’s proposed program includes the key elements described in RG 1.200, it may conclude that such a program is acceptable. 21. In the analysis of high winds, tornado frequencies developed with methods and data in NUREG/CR-4461, Revision 1, and based on data for the central region of the United States will normally be acceptable because the central region of the country has the highest occurrence rate of