Development of measures for the truncation uncertainty in fault tree analysis

The fault tree quantification uncertainty from the truncation error has been of great concern in the reliability evaluation of large fault trees and probabilistic safety analysis (PSA) in the nuclear field. This paper presents measures to estimate the amount of truncation error when quantifying fault trees with a truncation limit. The functions to calculate the measures are programmed into the new fault tree quantifier FTREX (Fault Tree Reliability Evaluation eXpert) and a Benchmark test was performed to show the efficiency of the measures. The developed measures are easily implemented into the existing fault tree solvers