# Model Engineering in a Modular PSA

Abstract : For the purpose of PSA (Probabilistic Safety Analysis) for complex industrial systems, often PSA models in the form of fault and event trees are developed to model the risk of unwanted situations (hazards). While the recent decades, PSA models have gained high acceptance and have been developed massively. This led to an increase in model sizes and complexity. Today, PSA models are often difficult to understand and maintain. This manuscript presents the concept of a modular PSA. A modular PSA tries to cope with the increased complexity by the techniques of modularization and instantiation. Modularization targets to treat a model by smaller pieces (the modules'') to regain control over models. Instantiation aims to configure a generic model to different contexts. Both try to reduce model complexity. A modular PSA enables to apply new functionality for model management. Current PSA model management is often characterized to be limited or inefficient. This manuscript shows new methods to manage the evolution (versions) and deviations (variants) of PSA models in a modular PSA. The concepts of version and variant management are presented in this thesis. In this context, a method to compare and fusion PSA models is precised. Model comparison provides important feedback to model engineers and model fusion targets to combine the work from different model engineers (concurrent model engineering). Apart from model management, methods to understand the content of PSA models are presented. The methods focus on highlighting the dependencies between modules rather than their contents. Dependencies are automatically derived from a model structure. They express relations between model objects (for example a fault tree may have dependencies to basic events). The visualization of those dependencies (for example in form of a model cartography) can constitute a crucial aid to model engineers for understanding complex interrelations in PSA models. Within the scope of this thesis, a software named Andromeda'' has been developed at EDF R&D to test and evaluate the concepts around a modular PSA. Andromeda is based on a modular and extensible architecture that can be customized to specific needs of customers. Apart from research interest, it has recently gained industrial interest. Andromeda has potential to augment existing PSA tools by specific functionality they lack and to promote common modeling standards and techniques within the international PSA community.
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Submitted on : Thursday, January 29, 2015 - 12:16:38 AM
Last modification on : Wednesday, March 27, 2019 - 4:41:27 PM
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### Identifiers

• HAL Id : tel-01110825, version 1

### Citation

Thomas Friedlhuber. Model Engineering in a Modular PSA. Computer Science [cs]. LIX, Ecole polytechnique; EDF R&D, 2014. English. ⟨tel-01110825⟩

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