Document: NUREG-0800
Document ID: 1877a6e5-f5a2-4394-bd63-c323831e96d0
Document Type: srp
Title: INTRODUCTION - TRANSIENT AND ACCIDENT ANALYSES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML2231/ML22319A149.pdf
Revision Date: 2023-07
Chapter: 15
Section ID: 15.0
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Content:
July 2023 portions of the Commission’s regulations, the staff will use the method described herein to evaluate conformance with Commission regulations. If an application proposes an alternative to a method described herein, the staff will evaluate whether the alternative demonstrates compliance with Commission regulations. The provisions of this SRP section apply to reviews of applications submitted six months or more after the date of issuance of this SRP section. The referenced regulatory guides contain implementation schedules for conformance to parts of the methods discussed herein. VI. DEFINITIONS Term Definition anticipated operational occurrences (AOOs) Conditions of normal operation that are expected to occur one or more times during the life of the nuclear power unit and include but are not limited to loss of power to all recirculation pumps, tripping of the turbine generator set, isolation of the main condenser, and loss of all offsite power. anticipated transient without scram (ATWS) A beyond-design-basis event consisting of an AOO followed by the failure of the reactor trip portion of the protection system specified in GDC 20. critical power ratio (CPR) The power in a fuel assembly that will cause some point in the assembly to experience boiling transition, divided by the actual assembly operating power. beyond-design- basis event A possible accident sequence not fully considered in the reactor design process because it was judged to be too unlikely. When such events are analyzed, analysis is typically performed with best-estimate inputs and assumptions in lieu of conservative design-basis modeling approaches. departure from nucleate boiling ratio (DNBR) The heat flux that will cause some point on a fuel rod to experience a rapid decrease in heat transfer due to the insulating effect of a vapor blanket that forms on the rod surface, divided by the actual local heat flux. 15.0-16 Draft Revision 4 – July 2023 DEFINITIONS (CONTINUED) Term Definition