Regulatory framework for declassification in Spain
In 2017, the process to obtain clearance authorization began. That same year, Order ETU/1185/2017 was published, establishing for the first time in Spain a specific regulatory framework for the clearance of residual materials from nuclear facilities. This regulation replaced the previous case-by-case authorization system and allowed licensees to carry out clearance directly, provided that the established reference levels were met.
Test Plan and equipment validation
Under this regulatory framework, the plant was required to submit to the Nuclear Safety Council (CSN) a schedule for implementing the Radiological Characterization Test Plan. The main tasks included, among others, the development of procedures, the execution of commissioning tests for the equipment, and the development of a methodology to determine hard-to-measure radionuclides.
The commissioning tests aimed to validate the gamma-spectrometry equipment (in this case ISOCS) for different geometries and waste configurations, ensuring their suitability as radiological characterization tools for material clearance. More than 500 tests were performed with varying fill levels, densities, measurement times, source distributions, and activity levels. The results demonstrated that both systems were adequate.
Hard-to-measure radionuclides and final authorization
Regarding hard-to-measure radionuclides—mainly alpha and beta emitters—the plant needed to develop its own scaling factors, as the existing ones were not applicable. Between 2017 and 2023, 43 samples were analyzed. Due to the low activity of key radionuclides, it was decided to assign an activity concentration (CdA) to each radionuclide based on geometric means and conservative values. Additionally, an annual verification procedure was established for future waste.
The documentation process included criteria for forming assessment units (UV), verification of clearance criteria, rejection management, quality control, and transfer to the Environmental Department.
The Test Plan, carried out in September 2024 in the presence of the CSN, verified all phases of the process.
Finally, on 6 November 2025, the CSN granted authorization for the clearance of scrap metal, limited to CMT containers under specific conditions of density, composition, filling level, measurement method, and isotopic type.
