Common Cause Failure
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A common cause failure (CCF) - also refered to as Common Mode Failure - is a failure where:
- The function of multiple CI is disrupted or destroyed by the same cause or hazard affecting the CI at the same location or area in the same time frame (e.g., a hurricane blocking roads and affecting telecommunication and power lines; a collapsed bridge which blocks inland shipping, road transport and caused disruption of gas, power and telecommunication lines)
- Item failures result from a single shared cause and coupling factor (or mechanism)
Contents
Definitions
National Definitions
Australia
Common mode failure is the coincident failure of two or more independent components as the result of a single cause; of particular concern in an instrument system incorporating redundancy where an event causes coincident failure of two or more of the normally independent channels. [1]
International Definitions
IAEA
Common cause failure is the failure of two or more structures, systems or components due to a single event or cause. [2]
Common mode failure is the failure of two or more structures, systems or components in the same manner or mode due to a single event or cause. [2]
Standard Definition
Discussion Topic
See also
- Geographical dependency - incorrect term often used for Common cause failure