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Description:
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Due to the scarcity of Human Reliability Analysis (HRA ) data , one of the key
elements of any HRA analysis is use of engineering judgment . The Electric Power
Research Institute (EPRI ) HRA Calculator guides the user through the steps of any
HRA analysis and allows the user to choose among analytical HRA methods . It applies
Accident Sequence Evaluation Program (ASEP ) , Technique for Human Error Rate
Prediction (THERP ) , the HCR /ORE Correlation , and the Caused Based Decision Tree
Method (CBDTM ) . This program is intended to produce consistent results among
different analysts provided that the initial information is similar . Even with this
analytical approach , an HRA analyst must still render several judgments . The objective
of this study was to evaluate the use of engineering judgment applied to the
quantification of post -initiator actions using the HRA Calculator . The Comanche Peak
Steam Electric Station (CPSES ) Level 1 Probabilistic Risk Assessment (PRA ) HRA was
used as a database for examples and numerical comparison . Engineering judgments
were evaluated in the following ways : 1 ) Survey of HRA experts . Two surveys were completed , and the participants
provided a range of different perspectives on how they individually apply
engineering judgment .
2 ) Numerical comparison among the three methods .
3 ) Review of CPSES HRA and identification of judgments and the effects on the
overall results of the database .
The results of this study identified thirteen areas in which an HRA analyst must
interpret and render judgments on how to quantify a Human Error Probability (HEP ) and
recommendations are provided on how current industry practitioners render these same
judgments . The areas are : identification and definition of actions to be modeled ,
identification and definition of actions to be modeled , definition of critical actions ,
definition of cognitive portion of the action , choice of methodology , stress level , rule - ,
skill - or knowledge -based designation , timing information , training , procedures , human
interactions with hardware , recoveries and dependencies within an action , and review of
final HEP . |