Expert systems for emergency alarms analysis during accident situations in nuclear reactors

Abstract Expert system development is an important application of artificial intelligence. During the last few years, many successful expert systems have been developed in various fields like medical diagnosis, geological exploration, office management, etc. Expert systems is a computer software which solves reasonably complex problems where normally one needs an expert in that field to solve them. Recently efforts are being made in developing expert systems to support the operating staff in nuclear reactors. Nuclear power plant is one of the most complex engineering systems and safe and reliable operation is of primary importance. In spite of many automatic and redundant safety systems there are some occasions when the operating staff have to analyse the alarms and take further safety actions. Few of the severe accidents like Three Mile Island in USA and Chernobyl in USSR are attributed to the errors made by the operating staff and/or management. Nuclear engineers or systems analysts who may be expert in analysing an accident situation and advise corrective safety actions may not be readily available during the accident situations in the nuclear power plants. It is possible to model such expert knowledge in expert systems and this can be applied in diagnosing an accident situation like the loss of coolant accident (LOCA) and act as an additional confirmatory aid to the operating staff. Two small expert systems examples have been developed and are explained in this paper. One identifies a spurious LOCA alarm in a heavy water research reactor. The second example identifies the type of medium/small leakage (LOCA) in a coolant circuit of a PWR and suggests the subsequent safety actions. Both the examples have been developed using the expert systems shell VP-expert. They are off-line usable and user interactive. We do not propose expert system application for very fast response safety actions like reactor scram. These two small expert system examples are essentially to support the feasibility study in their applications during accident situations in nuclear power plants.