This report presents a study performed on a set of common-cause failure (CCF) events within the Nuclear Energy Agency (NEA) International Common-cause Failure Data Exchange (ICDE) Project. The topic was improving testing.
The main objective of this topical report was to study CCF events where fault states or impairments could not be detected in normal recurrent tests because the scope of tests was insufficient or no appropriate tests existed. The report is mainly intended for designers, operators and regulators to broaden their understanding on reducing CCF risks by improving testing and to provide insight into relevant failure mechanisms.
It summarises the results of two data analysis workshops performed by the ICDE steering group, and presents CCF defence aspects for provision against CCFs by improving testing. The analysis included an assessment of the event parameters, event cause, coupling factor, detection method, corrective action and event severity.