A fault tree analysis is used to demonstrate the quantification of risk. The first step is the performance of a sensitivity analysis which gives an ordering of the critical components in the order of their importance. The second step is to quantify the failure probabilities of those components shown to be critical by the probit method using the applicable stress function. Component probabilities are reassembled with a data management program to obtain a quantification of the failure probability of the system. The costs incurred and/or saved in adjusting the system failure are coupled with probability to give a cost/benefit analysis.