Suppose

that a process plant has a large gas fired heater A hazard study has identified that the

combustion chamber could explode if there is a build up of unburnt gas and air after a loss of

flame event, leading to $5$ fatalities The rate of this explosion happening has been analysed to be

about $001$ per year $($every $100$ years$)$ The plant has an estimated lifetime of $20$ years This could

arise if the gas supply is not shut off as soon as the flame is lost The are $3$ functional safety

system options being considered

$$

Baseline Hazard

$$

Baseline hazard consequence

Frequency $=0\mathrm{.}01$ per yr $($every $100$ yrs

$$

Baseline hazard

Severity $=5$ deaths

$$

ALARP Option $1$:

$$

Reduces Frequency by factor of $10($to $0\mathrm{.}001)$: Costs $100$K

$$

ALARP Option $2$:

$$

Reduces Severity by factor of $5($to $1$ death$)$: Costs $10$K

$$

Perform CBA for:

$$

Option $1,$

Option $2,$ Option $1$ and $2$

$$

For purpose of CBA use

Cost of single death $=1,000,000$