Multi-Unit Analyses across Application Domains

Reliable systems such as nuclear power plants, oil tanks, computation clusters, wind farms, or satellites fail rarely. One could argue that studying accidents of an individual unit provides sufficient insight for risk-informed decision making. This approach might hide potential risks that arise from the fact that there are multiple units with a similar risk profile that share dependencies. A nuclear power plant might consist of several units located at the same site, an oil terminal contains almost identical tanks, and a wind farm comprises multiple wind turbines. Studying the effects of dependencies between units might increase risk understanding and provide new perspectives for system design and operation. We investigate feasibility of a multi-unit analysis for applications where models for individual units exist. The analysis methods might differ on the basis of the size and complexity of the models. Large nuclear power plant fault trees might require different algorithms than significantly smaller models of oil tanks. Our exploration is based on the multiunit sequence method developed for the nuclear industry. We also include comparisons with analyses that use Monte Carlo simulations.

Keywords: Multi-unit risk, Dependencies, Multi-unit sequences, Analysis algorithms.