Extension of the German database for common cause failure events

The first German data base for Common Cause Failures (CCF) had been set up for the German Risk study, Phase B, published in 1989. It was based on three sources: international operating experience from the OECD Incident Reporting System, the national operating experience reflected in the collection of reportable events and plant specific operating experience from the Nuclear Power Plant Biblis unit B. This data base was subsequently substantially extended in terms of additional events and extended observation periods where additional information was collected in the frame of further PSA studies und CCF projects. The reportable events were the key source for this extension. Using this improved data base an updated calculation of CCF probabilities has been performed which was published in the document on PSA data associated to the regulatory PSA guideline.