$4\mathrm{.}1.$ Consider the reactor shown in Figure $4\mathrm{.}1.$ The reaction is exothermic. A cooling system is

provided to remove the excess energy of reaction. In the event of cooling function is lost, the

temperature of the reactor would increase. This would lead to an increase in reaction rate

leading to additional energy release.

The results could be a runaway reaction with pressures exceeding the bursting pressure of the

reactor. The temperature within the reactor is measured and is used to control the cooling water

flow rate by a valve.

Figure $4\mathrm{.}1$: Schematic representation of a reactor.