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Chapter 19 Risk management 597
Failure over time is often represented as a failure curve. The most common form of this is the
so-called ‘bath-tub curve’ which shows the chances of failure being greater at the beginning
and end of the life of a system or part of a system.
Failure analysis mechanisms include accident investigation, product liability, complaint analysis,
critical incident analysis, and failure mode and effect analysis (FMEA).
➤ How can failures be prevented?
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There are four major methods of improving reliability: designing out the fail points in the operation,
building redundancy into the operation, ‘fail-safeing’ some of the activities of the operation,
and maintenance of the physical facilities in the operation.
Maintenance is the most common way operations attempt to improve their reliability, with three
broad approaches. The first is running all facilities until they break down and then repairing
them, the second is regularly maintaining the facilities even if they have not broken down, and
the third is to monitor facilities closely to try to predict when breakdown might occur.
Two specific approaches to maintenance have been particularly influential: total productive
maintenance (TPM) and reliability-centred maintenance (RCM).
➤ How can operations mitigate the effects of failure?
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Risk, or failure, mitigation means isolating a failure from its negative consequences.
Risk mitigation actions include:
– Mitigation planning.
– Economic mitigation.
– Containment (spatial and temporal).
– Loss reduction.
– Substitution.
➤ How can operations recover from the effects of failure?
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Recovery can be enhanced by a systematic approach to discovering what has happened to
cause failure, acting to inform, contain and follow up the consequences of failure, learning to
find the root cause of the failure and preventing it taking place again, and planning to avoid the
failure occurring in the future.
The idea of ‘business continuity’ planning is a common form of recovery planning.
Case study
The Chernobyl failure 13
At 1.24 in the early hours of Saturday morning on 26 April
1986, the worst accident in the history of commercial nuclear
power generation occurred. Two explosions in quick
succession blew off the 1,000-tonne concrete sealing
cap of the Chernobyl-4 nuclear reactor. Molten core fragments
showered down on the immediate area and fission
products were released into the atmosphere. The accident
cost probably hundreds of lives and contaminated vast
areas of land in Ukraine.
Many reasons probably contributed to the disaster.
Certainly the design of the reactor was not new – around
30 years old at the time of the accident – and had been