A reactor, utilizing toxic reagents, at a plant where you are a process engineer is known to experience pressure events once every two years (the pressure likely increases due to buildup of byproduct over time). When a pressure event occurs, the first safety measure in place is the opening of a spring-type relief, so that the release of toxic material is limited. The spring-type relief has an 80% probability of successfully opening and relieving the pressure. If the spring-type relief does not work, there is a back-up rupture disc that relieves the pressure at 1.05 times the maximum set point. This rupture disc has a 99% probability of successfully relieving the pressure. If these two reliefs do not work, the reactor is expected to fail and burst, causing a catastrophic event. If instead the pressure is relieved, either through the spring-loaded relief or through the rupture disc, the vented mass is passed to a flare system to burn off the material and render it non-toxic before being released to the atmosphere. The flare has a 93% probability of success. Failure of the flare leads to the uncontrolled release of toxic material. Fill out the event tree below based on this possible sequence of events (giving the expected occurrence of that event at each decision point) and calculate what is the overall expected occurrence of successful pressure relief with no toxic release, of toxic material release, and a catastrophic reactor failure due to pressure build-up.
Excess byproducts lead to overpressure
2/year