Integrating waste management into small modular reactor design from the start – “We aim to support the development of advanced reactor technologies”

Small modular reactors offer one of the most promising routes to decarbonising energy systems, which is why the policies and technologies surrounding them are advancing rapidly right now. For developers of small modular and advanced reactors, early consideration of waste management is essential. Decisions made during the early phases of reactor and fuel cycle design can have long-term implications for safety, licensing, costs and sustainability.

“For advanced reactors and SMRs, waste management cannot be considered only after the technology has been developed. It needs to be integrated into the design process from the very beginning to ensure lifetime cost efficiency and licensing,” says Erika Holt, Lead for Nuclear Energy Back End at VTT.

Key aspects in SMR waste management that need to be addressed include, for example:

• waste inventory, both from used fuel and reactor components,
• treatment, conditioning and recycling,
• storage and transport
• and final disposal. 

Waste management is s currently being studied by the OECD Nuclear Energy Agency’s WISARD project (Waste Integration for Small and Advanced Reactor Designs). This project explores how front-end and design phase decisions impact back-end strategies for sustainable future nuclear systems.

VTT is among the organisations contributing to the project, bringing expertise in nuclear systems, safety, and waste management to support the development of sustainable advanced reactor solutions.

“Finland is a global forerunner in nuclear waste management. Through the WISARD project, we are bringing together expertise across the nuclear fuel cycle to understand better how new reactor concepts will interact with existing waste management solutions,” says Holt.

One of the project’s key objectives is to identify areas where current back-end solutions may require adaptation or further innovation. By integrating waste management considerations early in the reactor lifecycle, developers can, for example:

• better understand the implications of different fuel cycle options,
• optimise reactor designs from a whole-system perspective,
• identify potential material challenges early and avoid costly changes later and
• improve the long-term sustainability of nuclear technologies.

The WISARD project is a three-year international collaboration bringing together organisations from across the nuclear sector. Officially launched by the NEA in May 2025, the initiative includes 21 participants from Europe, North America and Asia, representing research institutes, national laboratories, industry players and advanced reactor developers. 

VTT has been working on SMR and advanced reactor technologies for years, including the development of a simple low-cost nuclear reactor for district heating, LDR-50. The concept is currently being commercialized by a spin-out company Steady Energy for whom VTT works as a subcontractor.  

”SMRs are a potential way to decarbonise energy systems. At VTT, we actively study these technologies and support companies in evaluating reactor concepts and developing their roadmaps. With our comprehensive expertise from the nuclear field, we aim to support the development of advanced reactor technologies that are not only innovative but also sustainable across their entire lifecycle,” says Jani Halinen, Vice President of Nuclear Energy at VTT.

Companies and organisations working on advanced reactors and SMRs can turn to VTT for support in areas such as:

• Feasibility studies of SMR technology in the local energy networks for both power and heat production or connected to an industrial plant.  
• SMR technology evaluations, roadmapping and licensing.  
• Quantitative analysis of reactor physics and safety using VTT tools such as Apros®, Serpent, Kraken and others.  
• SMR fuel and reactor material inventory evaluations to assess back-end decommissioning and waste management, including final disposal.