(a) Define Fault Tree Analysis (FTA) and discuss the key elements involved in its application. (b) An operator is required to monitor a steam boiler. Under fault conditions, the operator is at risk from injury from explosion due either (i) the boiler burner being lit when operating with low water conditions (ii) overpressure. The expected frequencies of the failures that would lead to either of these effects are given in table 1. Table 1.0 Failure type Water level detector Electrical fault Pressure switch failure Relieve valve failure Frequency per year 0.1 0.05 0.1 0.05 Effect I (i) or (ii) li li Given that the operator is at risk for 20% of the time that the boiler is operating, construct and quantify a simple fault tree of the top event (injury to the operator)