Tritium is a rare and radioactive hydrogen isotope that sits at the heart of two major challenges in nuclear energy. In fusion reactors, it is the primary fuel. In fission reactors, particularly the next-generation designs under development in Europe, it is an unwanted byproduct that must be carefully monitored, contained, and managed.

For decades, the fusion and fission communities worked on tritium largely in parallel, each developing their own tools and methods. The TITANS project (Tritium Impact and Transfer in Advanced Nuclear ReactorS) set out to change that, by creating a genuine two-way exchange of knowledge and technologies between the two domains.

The technologies at the heart of TITANS originated from years of fusion R&D carried out at CIEMAT in Spain, CEA and CNRS in France, and the Jozef Stefan Institute in Slovenia, building on previous Euratom projects such as TRANSAT.

In the fusion context, these institutions developed a comprehensive suite of tools to handle tritium across all its forms:

• Transport modelling and simulation tools, including the EcosimPro TRITIUM toolkit developed by CIEMAT and EAI, designed to simulate tritium permeation, retention, and release in breeding blankets and plasma-facing components of devices such as ITER and DEMO.
• Advanced coatings and permeation barriers applied to structural steels (Eurofer) in liquid metal environments such as lead-lithium alloys.
• Innovative measurement techniques, including autoradiography, NMR, nuclear reaction analysis, and LIBS, enabling precise detection and quantification of tritium in solid, liquid, and gaseous phases.

Each of these was originally built with fusion reactors in mind. TITANS asked a straightforward question: do they also work in fission environments?

The TITANS consortium applied and benchmarked these fusion-derived methods against fission-oriented scenarios, focusing particularly on Sodium Fast Reactors (SFRs), a Generation IV reactor concept where tritium migration and retention represent critical safety and environmental concerns.

The results validated both the robustness of the fusion-derived tools and their practical applicability in fission settings. Modelling codes were cross-validated with fission-oriented simulations. Coating technologies were tested under sodium and lead-lithium conditions relevant to next-generation fission designs. Measurement techniques were refined to work reliably across both reactor types.