APPLICATION OF FBOLES - A PROTOTYPE EXPERT-SYSTEM FOR FAULT-DIAGNOSISIN NUCLEAR-POWER-PLANTS

The basic concept of a frequency-based on-line expert system (FBOLES) approach for the on-line fault diagnoses of nuclear power plants has b een previously presented in our companion papers. This paper reports o n the status of the prototype software development and the real time o n-line experiment results. The main steam and feedwater condensate sys tem (MSFCS, namely, the secondary loop) of a nuclear power plant (950 MW, three loops) simulated by the Tsinghua simulator has been selected as a target system at the present stage of development. The knowledge bases for MSFCS have been initially constructed. A total of 62 signal s from the simulator have been selected as the on-line evidence for di agnosis. Thirty-three fault experiments were performed in which 21 wer e detected accurately (only one candidate) by FBOLES immediately after the first abnormal signals were received and the other 12 were detect ed accurately within 0.5 to 3 min as the development of abnormality. T hese experiments include not only the failures of pumps, valves, pipes , etc., of MSFCS itself, but also the failures outside MSFCS. Three of them involve non-initiating events. As a software package, FBOLES can perform either the on-line diagnosis where the signals are input from the simulator directly or the off-line diagnosis that either repeats the on-line diagnosis in a selectable time scale by using the data rec eived on-line and stored on disk or allows users to input signals from a keyboard. Also, the integrated information base, including the modu lar mini knowledge bases and other necessary data, can be edited and a ssembled by users easily and compiled by FBOLES into coded format.