Addressing end of commercial operation challenges and emerging issues often require innovative and multidisciplinary solutions that involve elements of engineering from: materials, chemistry, stress analysis, thermal-hydraulic analysis, probabilistic assessment methods, examination and inspection approaches, and operational strategies. This is the case for most major nuclear plant systems and components, regardless of reactor type. The focus for the MCFD-2026 Conference is on the challenges, innovations, and experiences encountered when addressing issues of chemistry, materials, or fitness-for-service in nuclear power plants.