SAS-2, a computerised operator support system assisting in plant emergency shutdown

The paper describes a computerised operator support system called SAS-II. It has been developed under a joint research and development programme between Unit 2 at the Swedish nuclear plant Forsmark, the Swedish Nuclear Inspectorate (SKI), Vattenfall AB- former the Swedish State Power Board and the OECD Halden Reactor Project in Norway. The purpose of this project was to develop a function oriented advisory system assisting the shift supervisor in his observation and evaluation task after plant disturbances leading to emergency shut-down. To monitor this shutdown process the supervisor today applies a set of function oriented emergency procedures. After inclusion of SAS-II, this system will continuously give information to support the work with the emergency procedure (EOP). In addition the system will issue critical safety function alarms and explain why the critical safety functions have been challenged. The SAS-II system consists of two parts. One part is developed and executed under control of the real-time expert system G2. A knowledge-base has been constructed that represents non-successful behaviour of the plant automatics and control-systems in terms of the defined plant critical safety functions. The other part of SAS-II consists of a man-machine interface for the shift leader developed and executed under control of the PICASSO graphic display system. The present status of the system is an installation on the compact training simulator in Forsmark. A human factors validation has been undertaken using this installation, and results from this test will be presented. The future plans for the system is to verify the system further on a full-scale simulator, before a possible installation in the control room