Question 1

A plant is refining and processing brown sugar, which is more flammable than white sugar. Plant lifetime is 30 years.

a) Name one possible risk and one possible hazard that can occur at the plant.

b) A single channel trip has a failure rate of 0.37 failures per year on a duty where the demand rate is 1.5 demands per year. What is the plant hazard rate for proof test intervals of 1 week, 1 month and 1 year?

c) An operator in the plant is working in the control room. The FAR in his/her occupation is 2. What is the probability of the operator being killed at work in a given normal 40-hour work week?

d) A major incident occurred at the plant due to dust explosion. The explosion resulted in 8 fatalities, 15 permanent injuries, 30 serious injuries and 60 minor injuries. The probability of this explosion occurring has been estimated at 1 in 100 000 years. The disproportion factor (DF) for such a high hazard is 10. The cash valuations of preventing health and safety effects on people are presented in Table Q1.

FATALITY	1,336,800
INJURY
Permanent	207,200
Major	20,500
Minor	300

Calculate the reasonably practicable financial costs of avoiding the occurrence of this explosion.

e) This dust explosion in Q1d could have been prevented.

(i) Define dust explosion.

(ii) Describe in a few lines how dust explosions can occur.

(iii) Give suggestions on preventing dust explosions.