Optimal safety system design using fault tree analysis

This paper describes &design optimizatio$cheme for systems that require a high likelihood of functioning on demand. The$nal design specijication is achieved’by solving a sequence,of optimization problems. Each of these problems is dejined by assuming some form of the objective junction and specijying 4sub-region.af the design space over which this function will be representative of the system unavail-ability. An example of a high-pressure protection system has been used to demonstrate the practicality of the technique. Design parameters for this system include redundancy levels, the number of elements required for a voting system to function-'component> selection options and maintenance inspection intervals. Both implicit and explicit constraint forms have been used in the e x h p l e. The implicit constraints require a full system analysis to determine whether the current design is feasible or not. All system assessments have been curried out using fault tree analysis.