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Proceedings of the Eighth International Conference on Probabilistic Safety Assessment & Management (PSAM)

Editor
Michael G. Stamatelatos
Michael G. Stamatelatos
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Harold S. Blackman
Harold S. Blackman
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ISBN-10:
0791802442
No. of Pages:
2576
Publisher:
ASME Press
Publication date:
2006

One great challenge for improving Human Reliability Assessment (HRA) is the lack of relevant data to support the development of models and methods for assessing human performance. This paper reports a Nuclear Boiling Water Reactor simulator study that provides information on context effects on human performance in accident operation. The OECD Halden Reactor Project using the Halden Man-Machine Laboratory (HAMMLAB) performed the study.

Some of the commonly used Performance Shaping Factors used in HRA contain characteristics about impact of concurrent and competing activities, complexity and task load. The study reported here focused on the effect of an ambiguous secondary task on primary task performance. The study contained four variants of a scenario. A primary task of isolating a leakage from a system connected to the reactor tank was repeated in all four scenario versions. The primary task was evaluated as a relatively easy task. The scenario variants 2 to 4 contained a given secondary task with increasing levels of ambiguity. The first level of ambiguity was a missing component indication and the third and fourth level was misguiding process indications. The primary task and the secondary task occurred simultaneously in the scenarios. Seven three-manned control room crews ran all four scenario variants.

The results showed that a low level of secondary task ambiguity did not effect the performance time of the primary task while higher level of ambiguity did effect some of the crews' primary task performance times. The prolonged performance time of the primary task was mediated by crew characteristics such as division of work within the crew and attention to simultaneously occurring tasks. The results inform HRA by giving information on what characteristics of the context can be expected to effect on performance of primary task and what characteristics can be expected to not affect on the primary task.

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