A probabilistic modular Petri net framework for modeling IFMIF-DONES short beam stop maintenance operations

This paper introduces a modular high-level Petri net-based simulation framework designed to model the short beam stop (SBS) maintenance operations of the IFMIF-DONES irradiation facility. Building on earlier work focused solely on the test cell (TC), this study extends the simulation to the entire IFMIF-DONES facility using a modular Petri net (PN) approach, enabling downtime estimation and the assessment of shift configurations at both subsystem and facility levels. The modular approach decomposes the system into functional modules and submodules that represent workforce allocation and shift scheduling. Evaluation of the model is performed by integrating a randomized quasi-Monte Carlo (RQMC) simulation tool, complemented with a global sensitivity analysis (GSA) framework to quantify maintenance uncertainties, guide workforce distribution, reduce downtime, and enhance maintenance scheduling strategies. Simulation results show that initial SBS downtime projections exceed the facility’s 3-day operational threshold. However, the simulation-based search identifies the best workforce arrangements that reduce downtime by 62.5% compared to worst-case scenarios. This framework revealed diminishing returns beyond ten workers and highlighted practical strategies for workforce allocation. The study concludes with heuristic scheduling strategies to enhance workforce distribution and scheduling, providing a robust and scalable foundation for simulation-based maintenance planning and scheduling in advanced irradiation facilities.