ENRESA-CIEMAT Agreement 2026: what it means for the nuclear sector

Key data

Nuclear facilities and radioactive waste managers in Spain have a new element to monitor: the agreement signed between ENRESA and CIEMAT to develop an R&D project on the inventory of long-lived radionuclides and toxic and hazardous metals in low and medium activity waste (LMAW). The Resolution of April 10, 2026 from the Under-Secretariat published this agreement on April 18, 2026.

Although it does not impose direct obligations on private companies at this time, the nature of the project—improving technical knowledge about the most common waste in the nuclear sector—anticipates that its conclusions may condition future management plans and the requirements imposed on facilities that generate this type of waste.

What does this regulation establish?

The agreement formalizes collaboration between two key bodies in the Spanish nuclear system to address a specific technical need: to extend and optimize the inventory of long-lived radionuclides and toxic and hazardous metals present in low and medium activity waste.

The central elements of the agreement are:

• Promoting and waste management entity: ENRESA (Empresa Nacional de Residuos Radiactivos, SA, S.M.E.), responsible for managing radioactive waste in Spain.
• Research entity: CIEMAT (Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, O.A., M.P.), a leading public organization in energy and nuclear research.
• Project objective: Extension and optimization of the inventory of long-lived radionuclides and toxic and hazardous metals in low and medium activity waste (LMAW).
• Purpose: To strengthen national technical capacity in nuclear waste management, with direct implications for radiological safety and regulatory compliance.

Low and medium activity waste (LMAW) is the most voluminous waste in the nuclear cycle. It includes contaminated materials, tools, protective clothing, filters and other elements generated in nuclear power plants, medical and industrial facilities. Proper characterization of its inventory—especially of long-lived radionuclides and toxic metals—is essential to ensure long-term safety of permanent storage facilities.

Economic and operational impact

This agreement does not generate direct costs or immediate economic obligations for private companies in the sector. Its impact is indirect but potentially relevant in the medium term:

• Future regulatory requirements: The project results could lead to new waste characterization requirements for nuclear facilities, which would imply additional costs for analysis, classification and documentation.
• Waste management plans: The R&D conclusions could modify national radioactive waste management plans, affecting the obligations of waste-generating facilities.
• Radiological safety and compliance: Better inventory characterization strengthens the radiological safety framework, which may result in more stringent inspections or updating of internal protocols.
• Opportunities for the research sector: The agreement strengthens public-private collaboration in nuclear R&D, opening potential participation lines for companies specialized in nuclear services.

Who does it affect?

• Operating nuclear power plants: They are the main generators of LMAW and the most exposed to future changes in waste characterization requirements.
• Radioactive waste managers: Companies and organizations that manage, transport or store low and medium activity waste.
• Nuclear facilities undergoing decommissioning: They generate large volumes of LMAW and are subject to management plans that could be affected by the project results.
• Medical and industrial facilities with radioactive sources: They generate smaller volumes of LMAW but are equally subject to management regulations.
• Public research organizations: CIEMAT and similar entities that participate in the technical development of the nuclear sector.
• Nuclear services companies: Providers of analysis, characterization and waste management services that could see modified demand for their services.

Practical example

A nuclear power plant undergoing decommissioning generates thousands of cubic meters of low and medium activity waste: from contaminated equipment to construction materials. Currently, the characterization of this waste follows the protocols established in the current management plan.

If the R&D project between ENRESA and CIEMAT concludes that certain long-lived radionuclides or toxic metals were not sufficiently inventoried, the regulator could require a review of the inventory of already classified waste. This would imply for the facility: new laboratory analyses, updating safety documentation and, potentially, reclassification of some waste with the consequent impact on management and storage costs.

This is not an immediate risk, but rather a scenario that companies in the sector should keep on their medium-term planning radar.

What should companies do now?

1. Identify if your facility generates LMAW: Determine whether your activity produces low and medium activity waste and in what volume, to assess your exposure to future regulatory changes.
2. Review the current status of your waste inventory: Check that the characterization of your waste—especially regarding long-lived radionuclides and toxic metals—is up to date and documented in accordance with current requirements.
3. Monitor the results of the ENRESA-CIEMAT project: Establish a mechanism to track publications and conclusions from the R&D project, as its results could anticipate regulatory changes.
4. Review your waste management plans: Ensure that your LMAW management plans are aligned with current regulations and have room for adaptation to possible new requirements.
5. Consult with your specialist advisor in nuclear regulations: If your company is directly exposed to LMAW management, it is advisable to evaluate with an expert the potential impact of this agreement's results on your compliance obligations.