ALIBABA : a french expert system for PWR containment analysis in case of severe accident.

Severe Accident Management OECD workshop on operator training and instrumentation capabilities, 12-14/03/2001, Lyon, France.

The expert system ALIBABA has been developed by the Institute for Nuclear Safety and Protection (IPSN) in order to help its Emergency Centre evaluate the state of the third barrier and the connected circuits, in case of a severe accident on a 900 MWe French PWR. So as to detect and localize precociously any potential leak paths, the system analyses : - containment equipment availability, - containment isolation reports, - activity readings located in rooms and/or ventilation ducts. ALIBABA’s estimation is required prior to any source-term quantification. Indeed, potential leak paths may not be collected at the stack and such a situation requires the evaluation of an additional leak rate from the containment building. Therefore, ALIBABA enables the calculation of the radioactive release in a way as realistic as possible, before the evaluation of the radiological consequences and the prediction of short term counter-measures. ALIBABA can also be useful to understand which corrective actions could be undertaken in case of containment failure. This is obtained with synoptics of the modelling systems that cross the containment building into auxiliary systems. Should the occasion arise, IPSN may suggest its assumption to the plant operator. In any case, ALIBABA will make it easier for IPSN to analyse restoration actions adopted by the plant operator, in order to include their efficiencies in the source-term evaluation. ALIBABA is regularly used by emergency specialists during training sessions. It can also be used during emergency drills organised by the government authorities, depending on the containment scenario. In the near future ALIBABA will be available for 1300 and 1400 MWe French PWRs in addition to the 900 MWe PWRs. This widening is well under way. Intermediate tools are being developed in order to ease the processing of data and improve quality assurance and maintainability of ALIBABA.