Document: NUREG-0800
Document ID: 25cb3efc-9642-430d-a72f-52decd59b34f
Document Type: srp
Title: INTRODUCTION - TRANSIENT AND ACCIDENT ANALYSES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0707/ML070710376.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.0
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ns: • Major rupture of a 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) The sections of the SRP dealing with the individual events address specific postulated accidents and appropriate variations (e.g., design-specific variations). B. Categorization According to Type. AOOs and postulated accidents are also categorized according to type. The type of AOO or postulated accident is defined by its effect on the plant. For example, one type of AOO or postulated accident will cause the RCS to pressurize and possibly jeopardize RCS integrity. Another type will cause the RCS to depressurize and possibly jeopardize fuel cladding integrity. It is useful to categorize and organize analyses of AOOs and postulated accidents according to type, so that analysts can compare them on common bases, effects, and safety limits. Such comparisons can help to identify limiting events and cases for detailed examination and eliminate nonlimiting cases from further consideration. AOOs and postulated accidents can be grouped into the following seven types: (1) Increase in heat removal by the secondary system (2) Decrease in heat removal by the secondary system (3) Decrease in RCS flow rate (4) Reactivity and power distribution anomalies (5) Increase in reactor coolant inventory (6) Decrease in reactor coolant inventory (7) Radioactive release from a subsystem or component The review of AOOs and postulated accident analyses, within a type, can (and should) encompass a variety of cases, each designed to produce effects or results that challenge designated safety limits. For example, one case study of the turbine trip event, an