CCF Parameter Estimates

Quantitative results of the common-cause failure (CCF) data collection effort are presented for the current data set.

Equipment failures that contribute to CCF events are identified during searches of Licensee Event Reports (LER), Nuclear Plant Reliability Data System (NPRDS) failure reports, and Equipment Performance and Information Exchange (EPIX) failure reports.

The quantitative results are presented as both alpha factors and multiple Greek letter parameter estimations. The alpha factor distributions are also presented.

Same as the Industry Average Parameter Estimates 2020 Update, the CCF Parameter Estimations 2020 Update also used the most recent 15-year period data so that the analysis results could reflect the most recent industry performance yet still provide sufficient data.

Current Results:

• CCF Parameter Estimations 2020, INL/EXT-21-62940, Rev. 1
• CCF Parameter Estimates Spreadsheet 2020, Rev. 1

• Causal CCF Parameter Estimations 2020, INL/RPT-23-72728 (Note that due to the large size of the report, it is best to use the bookmark feature to navigate this PDF file.)
• Causal CCF Parameter Estimates Spreadsheet 2020

• CCF Parameter Estimates using Component-Specific Priors Spreadsheet 2020

Supporting Information:

• Component Boundaries
• Component-Specific CCF Prior Distributions, INL-EXT-21-65527, Rev. 2
• 2015 CCF Generic and Causal Prior Distributions, INL-EXT-21-43723
• Alternative CCF Models for Event Assessment, INL-EXT-21-33376
• Common-Cause Failure Database and Analysis System, NUREG/CR-6268, Rev. 1
• Guidelines on Modeling Common-Cause Failures in Probabilistic Risk Assessment, NUREG/CR-5485

Historical Results:

• Parameter Estimations 2015
• Parameter Estimations 2012
• Parameter Estimations 2010
• Parameter Estimations 2009
• Parameter Estimations 2007
• Parameter Estimations 2005
• Parameter Estimations 2003
• Common-Cause failure Parameter Estimations, NUREG/CR-5497