(Simulation Code System for Integrated Safety Assessment)

Safety Margin Applications and Assessment.

SCAIS is a simulation framework; it is being developed to check the validity and consistency of many assumptions used in the Safety Analysis. This diagnostic method is based on advanced dynamic reliability techniques on top of using classical Probabilistic Safety Analysis (PSA) and Deterministic Safety Analysis (DSA) technics, and allows for checking at once many aspects of the safety assessments, making effective use of regulatory resources.

Apart from a theoretical approach that is at the basis of the method, application of ISA requires a set of computational tools. Steps done in the development of ISA started by development of a suitable software package called SCAIS that comprehensively implies an intensive use of code coupling techniques to join typical TH analysis, severe accident and probability calculation codes. The final goal is to dynamically generate the event tree that stems from an initiating event, improving the conventional PSA statistic approach and calculate Damage Exceedance Frequency (DEF), figure of merit for Safety Margin Assessment..

In this figure, we  the obtained Dynamic Event Tree (DET) and the pressure of primary system  of a tarnsient simulated with SCAIS is shown.

The current SCAIS development includes as main elements DENDROS, the Event Scheduler Management Module. The Dynamic Probability Calculator, the Simulations Driver, BABIECA, and the Plant Models, figure 2.