Development of a situation awareness measure to evaluate advanced alarm systems in nuclear power plant control rooms

Abstract

The process controller is required to remain updated regarding developments in the dynamically changing process state, this being referred to as the maintenance of situation awareness. Alarm systems play an important role within this task, and therefore a measure of how effective the system is for enhancing the operator's situation awareness is desirable. One proposed measure is the Situation Awareness Control Room Inventory (SACRI). The methods and results of four simulator studies undertaken to develop and evaluate SACRI are outlined in this paper. It is concluded that SACRI is of use alongside measures such as detection time and diagnostic accuracy in simulator-based evaluations of alarm system design. IntroductionThe operator of a nuclear power plant must have knowledge of the current process state at all times, and the ability to use this knowledge effectively in predicting future process states and controlling the process to attain operational goals (Bainbridge 1978, Bainbridge 1983, Endsley 1995a, Wickens 1992, Wirstad 1988. Critical to this is information obtained from alarm systems, since alarms will often be the operator's first indication of a change in the process state information, and will then also act as invaluable process status information when the operator comes to diagnose disturbance causes and plan remedial actions (Haugset 1990, Marshall and Baker 1994, Stanton 1994. As a negative example of this, nuclear power plant incidents such as at Three Mile Island (Kemeny 1979) have shown inadequate alarm systems to be a significant contributing factor within the failure to correctly diagnose the disturbance cause, and it is such incidents that have motivated the development of advanced computer-based alarm systems (Bye et al. 1994).Advanced alarm systems use new methods of alarm generation, structuring, and presentation to enhance the effectiveness with which alarm information is obtained and processed by the operator. Example design concepts include the following (Bye et al. 1994):

Comparative study of three training methods for enhancing process control performance: Emphasis shift training, situation awareness training, and drill and practice

“…Endsley, 1995b), but in recent years other fields have followed, including process control (e.g. Hogg, Follesø, Strand-Volden, & Torralba, 1995). In process control, operators have to monitor plant states, alarm screens and panels, and to observe the state of numerous system parameters and patterns among them in order to gather information about the functioning of the system and future process state changes (Endsley, 1995b;Vicente, Mumaw, & Roth, 2004).…”

“…There were twelve questions in total (six measurements with each two items). The responses were then compared to logged CAMS data to determine whether the responses by the participants were correct (for this approach see Hogg et al, 1995Hogg et al, , p. 2411.…”

“…To check whether SA training was improving SA, we measured the latter index by means of the SA Control Room Inventory (Hogg et al, 1995), which was adapted for application to CAMS. The inventory was developed for use in process control research based on the Situation Awareness Global Assessment Technique (Endsley, 1995a).…”

Situation awareness measurement: A review of applicability for C4i environments

“…Techniques such as SAGAT (Endsley 1995b) and SART (Taylor 1990) have been applied in a number of areas, including military aviation (Endsley 1995b), air traffic control (Endsley and Kiris 1995), military operations , driving (Walker, Stanton and Young 2004) and the process industry (Hogg et al 1995).…”

“…The situation awareness control room inventory (SACRI) is an adaptation of SAGAT (Endsley 1995b) and uses the freeze technique to administer control room based SA queries. SACRI was developed as the result of a study investigating the use of SAGAT in process control rooms (Hogg et al 1995).…”