Containment by-pass and isolation failure detection with the expert system ALIBABA

In the event of an accident arising in an EDF (Electricite de France) pressurized water reactor, the IPSN Emergency Technical Centre (CTC) would be entrusted to provide the safety authorities with technical assistance. As pad of this responsibility it would analyse and forecast the barriers status (fuel clad, reactor coolant system, containment building), and the related safety functions (subcriticality, water inventory, primary pressure and temperature control, confinement). Its assignments would also require it to evaluate the kinetics and magnitude of a possible fission products release, in progress or to come, so as to advise necessary counter measures in order to ensure the surrounding population's protection, should the occasion arise. A realistic assessment of the release requires a good knowledge of the containment quality. It is therefore important to detect potential isolation faults (isolation failure or by-pass of the third barrier) as soon as possible. Once these leaks are identified, the plant operator will set required corrective arrangements rapidly. The CTC would follow up his actions closely. If none of them happen to be effective, containment leakage would be taken into account when estimating releases. Work of the emergency team lies indeed in two main points: early localization of isolation failure or containment by-pass; following up of the plant operator actions meant to remedy the problem. In order to meet these two requirements IPSN has developed an expert system named ALIBABA. Part one presents its advantages, whereas part two describes the expert system. Part three deals with the software environment and part four offers an example of the help provided by ALIBABA