E.3 Common Cause Failure Analysis
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Fig. E.3 Probability of
human failure in responding
to a loss event
A significant challenge within the field of human reliability analysis (HRA) is
the limited availability of data (statistics) to describe human reliability in a realistic
environment (such as from training in a plant simulator).
Table E.1 Examples of types of human errors
HRA error category
Type of deviation
Error of omission
Omission error:
– Task forgotten
– Step neglected
Error of commission
Operation error:
– Wrong operations
– Wrong positions
– Wrong command/information
– Wrong sequence
– Time error (too early/too late)
– Quantitative error (too much/too little)
Error of cognition
Perception, diagnostics, decision error:
– Wrong correction measure
– Mix-up
– Ignorance of critical deviation
E.3
Common Cause Failure Analysis
As introduced in Sect. 7.1.2, multiple safeguards are often used in the chemical
process industry to reduce process risks. This means that an accident can only
occur when multiple safeguards fail. This can result from the independent failure
of each safeguard or from a single failure event that causes multiple safeguards
simultaneously to fail. The latter is known as a dependent failure event or as a
common cause failure.