Use a simple fault tree to estimate the overall frequency of activation of a relief device caused by either failure of a pressure regulator or overheating of tank contents due to a failed temperature control. Use a failure frequency of 0.1/yr for the pressure regulator and 0.2/yr for the temperature control. Assume a high temperature interlock exists which shuts off heating of the temperature control with a Probability of Failure on Demand (PFD) of 0.1. Show your results