Risk-based inspection guide for Three Mile Island Nuclear Station Unit 1

Technical Report · Mon Feb 01 04:00:00 EST 1993

OSTI ID:7086891

Harrison, D G; Gore, B F; Vo, T V; Moffitt, N E ^[1]; Young, F I; Hernan, R W ^[2]

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1. Pacific Northwest Lab., Richland, WA (United States)
2. Nuclear Regulatory Commission, Washington, DC (United States)

The level one probabilistic risk assessment (PRA) for Three Mile Island Nuclear Station Unit 1 (TMI-1) has been analyzed to identify plant systems and components important to minimizing public risk, as measured by system contributions to the annual probability of core damage, and to identify the primary failure modes of these components. This report presents a series of tables, organized by system and prioritized by risk importance, which identify components associated with over 95% of the inspectable risk due to plant operation. The systems addressed, in descending order of importance, are: the Decay Heat Removal, High Pressure Injection, Decay Heat Cooling Water, AC Power, Nuclear Services Cooling Water, Main Steam, Emergency Feedwater, Reactor Coolant System Pressure Control, Intermediate Closed Cooling Water, Instrument Air, DC Power, and Engineered Safegards Actuation Systems. This 9 is based on the Fussel-Vesely Importance Measure of risk importance, i.e., the fraction of the total annual probability of core damage which involves failures of the system of interest. Though not involved in the prevention of core damage and thus not ranked, containment protection systems are of fundamental importance in preventing and minimizing public risk due to a release of radionuclides, should core damage occur. Therefore, containment protection systems are included in this report, consisting of the Reactor Building Isolation, Reactor Building Spray, and Reactor Building Emergency Cooling Systems.

• Research Organization: Nuclear Regulatory Commission, Washington, DC (United States). Div. of Systems Safety and Analysis; Pacific Northwest Lab., Richland, WA (United States)
• Sponsoring Organization: NRC; Nuclear Regulatory Commission, Washington, DC (United States)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 7086891
• Report Number(s): NUREG/CR-5488; PNL--7187; ON: TI93009027
• Country of Publication: United States
• Language: English

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