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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m (PWR and BWR) • Minor reactor coolant system (RCS) leak or loss of reactor coolant such as from a ruptured small pipe or from a crack in a large pipe (PWR and BWR) • Minor secondary system break (PWR) • Loss of offsite power (PWR and BWR) • Operation with a fuel assembly in an improper position (PWR and BWR) • Inadvertent opening of a pressure relief valve (PWR and BWR) • Loss of feedwater heating (PWR and BWR) • Trip of any or all recirculation pumps (BWR) • Inadvertent pump start in a hot recirculation loop (BWR) • Condenser tube leak (BWR) • Startup of an idle recirculation pump in a cold loop (BWR) Postulated accidents are unanticipated occurrences (i.e., they are postulated but not expected to occur during the life of the nuclear power plant). Note that some licensing basis documents may use the term “limiting fault” consistent with RG 1.70. The following are examples of postulated accidents considered in previous licensing reviews for currently operating PWR and BWR designs: 15.0-4 Draft Revision 4 – July 2023 • Rupture of a large pipe containing reactor coolant up to and including double-ended rupture of the largest pipe in the reactor coolant pressure boundary (PWR and BWR) • Ejection of a control rod assembly (PWR) • Control rod drop accident (BWR) • Major secondary system pipe rupture up to and including double- ended rupture (PWR and BWR) • Single reactor coolant pump locked rotor (PWR) • Seizure of one recirculation pump (BWR) • Steam generator tube rupture (PWR) • Fuel handling accident or cask drop (PWR and BWR) Finally, insights from operating experience have prompted regulatory actions to address a limited set of events beyond the scope of the design-basis criteria used to evaluate reactor designs. These beyond-design-basis events involve conditions not fully considered in the design process (e.g., the occurrence of multiple, independent failures) because they were judged to be too unlikely. Considering