A new hybrid method for fault tree analysis

This paper describes a new method for determining the significant minimal cut sets of complex fault trees. It can be classified as hybrid, being based on the application of both Top Down and Bottom Up reduction approaches. This solution has been adopted particularly to accurately estimate the truncation error when the probabilistic cut-off technique is applied. Experimental results on real fault trees proved that the degree of conservatism of the truncation error is negligible at any practical combination of the probabilistic and logical threshold values. ew fault tree analysis procedure has been implemented, in C language, in the second version of the computer programme ISPRA-FTA.