This article is an analysis based on our experience with the Fractal component model of the need of reliability for dynamic reconfigurations in component based systems. We make a proposal to ensure this reliability for concurrent and distributed Fractal applications. We started from the definition of ACID properties in the context of dynamic reconfigurations in component models and we propose to use integrity constraints to define system consistency and transactions for guaranteeing the respect of these constraints at runtime. Moreover we manage concurrency between reconfigurations by avoiding potential conflicts between reconfiguration operations. Finally, a recovery mechanism has been conceived to deal with failures.