Lessons Learned From the Decommissioning Process Affected by an Accident During Operation: The Case of A1 NPP in Slovakia

Decommissioning of NPP’s with standard shutdown is currently well known process. The A1 NPP in Slovakia was shutdown in 1977 after the accident in the core which caused the damage of the fuel and contamination of systems. Long period from 1977 to 2008 was needed to manage issues resulting from affecting the systems and structures of A1 NPP and the environment by the accident. Management of the damaged spent fuel, decontamination of the primary circuit and other processes generated large amounts of alpha bearing waste, mostly liquid, having sludge phases with specific physical-chemical and radiological properties. Up to 1994, the approach for eliminating the consequences of the accident was based on safety priorities. The systematic approach, which includes also the rehabilitation of the affected environment, was implemented in the period 1994–2008. The process includes also establishing of the decommissioning infrastructure, legislative and funding system with the aim to implement the standard decommissioning procedures after 2008. However, the specific aspects, especially the level and radio-nuclide composition of contamination of systems and structures will remain. For final decommissioning 2008–2033, the approach was selected which foresees four licensed phases. This approach enables proper planning and performing of individual decommissioning phases.