Practical Application of the MFM Suite on a PWR System: Modelling and Reasoning on Causes and Consequences of Process Anomalies

Multilevel Flow Modelling (MFM) is a functional modelling methodology which applies means - end and parts - whole decomposition and aggregation techniques to handle the complexity of engineering systems. It has been adopted in several case studies to model the process goal and functions of PWR systems. Two of the modelling examples can be found in HWR - 990 and HWR - 1059. The inherent causal reasoning capability enabled the developed MFM models to be used for diagnostic and prognostic analysis. These MFM models h ave been used to develop the basis for implementing operator support tools, with the aim to facilitate the plant operators to evaluate and understand plant situations. The theoretical aspects have been established for the cooperative development of an MFM software tool, namely MFM Suite, by the Halden Reactor Project (HRP) and the Technical University of Denmark (DTU). The MFM Suite is equipped with an MFM Model Editing Interface to facilitate the modelling process and MFM model analysis modules to run diag nosis and prognosis analyses based on developed models. New features of the MFM Suite also include making corresponding process diagram for the plant being modelled with MFM and linking the MFM model to its process components. The purpose of this report is to make a comprehensive demonstration of how to use the MFM Suite to develop MFM models and run causal reasoning for abnormal situations. This report will explain the capability of representing process and operational knowledge by using the MFM methodolog y, and demonstrate how the model combined with the MFM reasoning can be used to evaluate the plant state, identify the current situation and support operational decisions. The report will provide a detailed explanation of MFM concepts by modelling the prim ary side system of the Ringhals Westinghouse PWR and demonstrate the MFM reasoning for accident situation.