Consider the chemical reactor system shown in Figure 11-8. This system is identical to the system shown in Figure 10-6, except that a high-temperature alarm has been installed to warn the operator of a high temperature within the reactor. The event tree for a loss-of-coolant initiating event is shown in Figure 11-9. Four safety functions are identified. These are written across the top of the sheet. The first safety function is the high-temperature alarm. The second safety function is the operator noticing the high reactor temperature during normal inspection. The third safety function is the operator reestablishing the coolant flow by correcting the problem in time. The final safety function is invoked by the operator performing an emergency shutdown of the reactor. These safety functions are written across the page in the order in which they logically occur.