Regional Basic Professional Training Course in Korea

11. Human Performance: A Perspective on Human Factors
Examples of action tasks include operating equipment, performing line‐ups, starting
pumps, conducting calibration or testing, and other activities performed during the course
of following plant procedures or work orders. Diagnosis tasks consist of reliance on
knowledge and experience to understand existing conditions, planning and prioritizing
activities, and determining appropriate courses of action. Base error rates for the two task
types associated with the SPAR‐H method were calibrated against other HRA methods.
The calibration revealed that the SPAR‐H human error rates fall within the range of rates
predicted by other HRA methods.
11.4.2. Cognitive Control Based Technique
Erik Hollnagel has developed this line of thought in his work on the Contextual Control
Model (COCOM) [Hollnagel, 1993] and the Cognitive Reliability and Error Analysis
Method (CREAM) [Hollnagel, 1998]. COCOM models human performance as a set of
control modes ‐‐ strategic (based on long‐term planning), tactical (based on procedures),
opportunistic (based on present context), and scrambled (random) ‐‐ and proposes a
model of how transitions between these control modes occur. This model of control
mode transition consists of a number of factors, including the human operator's estimate
of the outcome of the action (success or failure), the time remaining to accomplish the
action (adequate or inadequate), and the number of simultaneous goals of the human
operator at that time. CREAM is a human reliability analysis method that is based on
COCOM.
CREAM is a second generation HRA method. However compared to many other such
methods, it takes a very different approach to modeling human reliability. There are two
versions of the technique, the basic and the extended version, both of which have in
common two primary features; ability to identify the importance of human performance
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