Appropriate choice of alarm system technologies: EPRI research

Human factors engineering guidance for the review of advanced alarm systems

“…Discussion: EPRI research (Fink et al, 1992) has found that CRT presentations were superior to tiles for highlighting alarms that were "unusual" for a given transient. In addition, this guideline is consistent with the high-level design review principle of Situation Awareness (see Appendix A).…”

“…Discussion: The suppression of alarms, such as the typical alarms associated with reactor and turbine trip, has been shown to reduce the number of "maverick" alarms (those not typically occurring during a plant trip) missed by the operators by 50 percent (Fink et al, 1992). However, it should be noted that some operators may object to such suppression since the timing of some of the normal trip-related alarms facilitates the crew's understanding of transients.…”

“…The roles of alarm systems in NPPs have typically been quite complex, Le., providing a first alert to anomaly or status and providing a source of information to operators to aid decision making. The importance of the multiple roles of alarm systems has been noted by many researchers (e.g., Fink et al, 1992;Kragt et al, 1983;MPR Associates, 1985;Sheehy et al, 1993). To support the different functions of the alarm system, multiple display formats may be required, e.g.…”

“…Finally, in a study conducted for comparing conventional and CRT-based alarm presentations (Fink et al, 1992), one of the experimental conditions included a CRT presentation of alarms where the typical alarms associated with reactor and turbine trip were suppressed. This presentation reduced the number of "maverick" alarms (those not typically occumng during a plant trip) that were missed by the operators by approximately 50 percent in comparison to a typical tile display.…”

“…One study (Fujita, 1988 and found no effect for the detection of initial disturbances, but found improved performance in the detection of secondary malfunctions (which is a significant problem). Another study (Fink et al, 1992) found a positive effect on detection of unusual alarms, but raised a question regarding possible trade-offs with the loss of information making the operator's understanding of events more difficult. Finally, interaction effects with scenarios seems to be an important consideration.…”