Document: NUREG-0800
Document ID: 7916b088-fb90-4163-84fe-027bd315bcc5
Document Type: srp
Title: REVIEW OF RISK INFORMATION USED TO SUPPORT PERMANENT PLANT-
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0717/ML071700658.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.2
CFR Part: 
CFR Title: 

Content:
accident scenarios. 19.2-83 June 2007 • Degrade multiple levels of defense, or cornerstones in the reactor oversight process, through plant operations or situations not explicitly considered in the development of the regulations, for example, advanced applications of digital instrumentation and controls in which the licensee does not address or comply with regulatory guidance concerning evaluation of defense in depth and diversity in digital instrumentation and control systems. • Significantly reduce the availability or reliability of structures, systems, or components that are risk significant but are not required by regulations, for example, amendment requests that as an unintended consequence compromise the effectiveness of the Mark I hardened wetwell vent system in protecting against containment overpressure failures in accidents beyond the design basis, or the diversity of the turbine-driven auxiliary feedwater pumps provided in response to NUREG-0737, Section II.E.1.1. • Involve changes for which the synergistic or cumulative effects could significantly impact risk, for example, power uprate requests that would increase operating power well beyond the levels approved in previous uprates and would introduce or substantially increase the frequency of risk-significant core damage sequences. If, upon further consideration, it is believed that approval of the request would compromise the safety principles described in Regulatory Guide 1.174 and substantially increase risk relative to the risk acceptance guidelines contained in the regulatory guide, the reviewers should inform NRC management of the risk concerns and the need to further evaluate the risk associated with the request. In such instances, the reviewers, with management concurrence, should ask the licensee to address the safety principles and the numerical guidelines for acceptable risk increases contained in Regulatory Guide 1.174 in its submittal. The reviewers may alternatively ask the licensee