Community Research and Development Information Service - CORDIS


The knowledge handbook describes the theoretical aspects, the analysis methods and the main characteristics of FTA and PTD modules of the ASTRA toolkit, a Windows 95/NT interactive programme package for fault tree analysis.

ASTRA allows to analyze fault trees containing the following logical operator: AND, OR, NOT, K/N, XOR and INH. Boundary conditions can be defined to rapidly analyze trees conditioned to the state of one or more components.

Two different methods can be used to determine the minimal cut sets (MCs): one is based on the Binary decision Diagrams approach, while the other method implements the Bottom Up reduction technique of the classical cut sets manipulation approach.

Besides cut-off methods based on cut sets order and probability, a new cut-off type has been implemented based on the number of significant MCS (SMCS). For documentation purposes, the user may customize the contents of the output file; it can contain both alphanumerical data and graphical representation of the input fault tree. ASTRA-FTA is a complete fault tree analysis program , it also contains the probabilistic sub-module to determine; unavailability, expected number of failures and components importance measures at the mission time. This report also describes the set of equations implemented in the ASTRA-PTD program for time dependent probabilistic analysis lysis

Additional information

Authors: CONTINI S, ISIS, Ispra (IT)
Bibliographic Reference: EUR 18727 EN, (1999) 55pp.
Availability: Available free of charge from CCR Ispra (IT)
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