THE DEVELOPMENT AND APPLICATION OF THE ACCIDENT DYNAMIC SIMULATOR FORDYNAMIC PROBABILISTIC RISK ASSESSMENT OF NUCLEAR-POWER-PLANTS

This paper describes the principal modelling concepts, practical aspec ts, and an application of the Accident Dynamic Simulator (ADS) develop ed for full scale dynamic probabilistic risk assessment (DPRA) of nucl ear power plants. Full scale refers not only to the size of the models , but also to the number of potential sequences which should be studie d. Plant thermal-hydraulics behaviour, safety systems response, and op erator interactions are explicitly accounted for as integrated active parts in the development of accident scenarios. ADS uses discrete dyna mic event trees (D-DET) as the main accident scenario modelling approa ch, and introduces computational techniques to minimize the computer m emory requirement and expedite the simulation. An operator model (incl uding procedure-based behaviour and several types of omission and comm ission errors) and a thermal-hydraulic model with a PC run time more t han 300 times faster than real accident time are among the main module s of ADS. To demonstrate the capabilities of ADS, a dynamic PRA of the Steam Generator Tube Rupture event of a US nuclear power plant is ana lyzed. (C) 1996 Elsevier Science Limited.