The Advanced Candu reactor annunciation system - Compliance with IEC standard and US NRC guidelines

Annunciation is a key plant information system that alerts Operations staff to important changes in plant processes and systems. Operational experience at nuclear stations worldwide has shown that many annunciation implementations do not provide the support needed by Operations staff in all plant situations. To address utility needs for annunciation improvement in Candu plants, AECL in partnership with Canadian Candu utilities, undertook an annunciation improvement program in the early nineties. The outcome of the research and engineering development program was the development and simulator validation of alarm processing, display, and information presentation techniques that provide practical and effective solutions to key operational deficiencies with earlier annunciation implementations. The improved annunciation capabilities consist of a series of detection, information processing and presentation functions called the Candu Annunciation Message List System (CAMLS). The CAMLS concepts embody alarm processing, presentation and interaction techniques, and strategies and methods for annunciation system configuration to ensure improved annunciation support for all plant situations, especially in upset situations where the alarm generation rate is high. The Advanced Candu Reactor (ACR) project will employ the CAMLS annunciation concepts as the basis for primary annunciation implementations. The primary annunciation systems will be implemented from CAMLS applications hosted on AECLmore » Advanced Control Centre Information System (ACCIS) computing technology. The ACR project has also chosen to implement main control room annunciation aspects in conformance with the following international standard and regulatory review guide for control room annunciation practice: International Electrotechnical Commission (IEC) 62241 - Main Control Room, Alarm Function and Presentation (International standard) US NRC NUREG-0700 - Human-System Interface Design Review Guidelines, Section 4 - Alarm System (Regulatory review guide) In order for the ACR annunciation system to comply with IEC-62241 and NUREG-0700, the CAMLS concepts must satisfy their respective requirements and guidelines. This paper will provide a summary of how CAMLS complies with IEC-62241 and NUREG-0700. Overall, the CAMLS-based annunciation requirements conform to the intent of the recommended annunciation practices included in both these documents. However, there are minor differences in requirements interpretation and annunciation practice between CAMLS implementation concepts and the recommended practice in each document. Generally the differences with IEC-62241 revolve around definitions, the display properties of new alarms, and video display unit (VDU) alarm display organization. The differences with NUREG-0700 revolve around segregation of status alarms, the use of spatially dedicated, continuously visible displays, simultaneous display of high-priority alarms, audible signals for alarm states and reminder signals, blank lines in alarm message lists and manual silencing. These minor differences are discussed and rationales for the CAMLS implementation concepts are provided. (authors)« less