Draw the event tree for the following problem and find the probabilities for shut$-$down and runway outcomes.

$$ Initiating Event: Loss of coolant

Four safety interventions

$-$High temperature alarm

$-$Operator noticing the high temperature during normal inspection

$-$Operator re$-$establishes the coolant flow

$-$Operator performs emergency shutdown of reactor

Assume loss of coolant occurs once per year $($occurrence frequency $1/$yr$)$

Alarm failure rate is $0\mathrm{.}015$ failures$/$demand

Operator fails to notice high reactor temperature $0\mathrm{.}20$ failures$/$demand

Operator successfully restart coolant flow $0\mathrm{.}70$ success$/$demand

Operator successfully shuts down reactor $0\mathrm{.}88$ success$/$demand

Outcomes

$-$Continued operation

$-$Shut down

$-$Runaway $($Evacuation$)$