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 50 fatalities, 100 permanently injured, 300 seriously injured and 1000 slightly injured. The rate of this explosion happening has been analysed to be about 1 x 10-3 per year, which is 1 in 1,000 per year. 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 burner controls will be fitted with a flame out detection sensor that will trip out the main and pilot gas supplies as soon as the flame is lost. This function is separate from the purge timer sequencing control system operating the ignition unit for the pilot flame, the flame failure protection system is clearly going to qualify as a functional safety system. Using values in Table 1, determine how much could the company reasonably spend to eliminate (reduce to zero) the risk from the explosion?

Level of Harm VPF/VPI Individual Death resulting from Accident (Value of Preventing a Fatality - VPF) f2,000,000 Individual Permanently incapacitating RIDDOR' Injury (Value of Preventing an Injury - VPI) E229,291 Individual Recoverable Serious RIDDOR Injury (Value of Preventing an Injury - VPI) f23,689 Individual Slight Non-RIDDOR Injury (Value of Preventing an Injury - VPI) (2,099 Table 1 - The monetary valuations of preventing health and safety effects on people