How can a process occurring in the Sun be replicated on Earth?

University of Latvia (LU) researchers are working on future nuclear fusion technologies.

Author: Matīss Sondars (Researcher at the Institute of Chemical Physics, Faculty of Exact Sciences and Technology, University of Latvia)

Nuclear fusion is a process in which a large amount of energy is released through the merging of light atomic nuclei. This process also takes place inside the Sun. Although nuclear fusion is not yet used for commercial energy production, scientists worldwide are working on its development, as it could provide efficient energy generation in the future with relatively low levels of radioactive waste.

Researchers from the Institute of Chemical Physics (ICP) at the Faculty of Exact Sciences and Technology of the University of Latvia are also involved in this field, collaborating with the Latvian companies Naco Technologies and Allatherm. They are developing solutions for the separation and purification of tritium—a radioactive isotope of hydrogen. As tritium is intended for use as nuclear fuel in fusion reactors in the future, efficient methods for its production and processing are crucial for the development of nuclear energy.

What is tritium, and why is it important?

Tritium is an isotope of hydrogen that differs from the most common hydrogen isotope—protium—by having two additional neutrons in its atomic nucleus; consequently, its nucleus is unstable and radioactive. In nuclear fusion, energy is generated through the fusion of tritium and deuterium (heavy hydrogen) nuclei, a process that releases a vast amount of energy.

In addition to its potential use in nuclear fusion, tritium is employed as a radiotracer in water cycle studies and in the fields of biology and environmental science, as well as in certain self-illuminating materials and devices, such as watch dials.

Tritium occurs in nature in very small quantities. A small fraction is formed in the atmosphere under the influence of cosmic radiation, while elevated levels of tritium in the environment have historically also resulted from nuclear weapons testing.

However, a significant portion of tritium today is associated with the nuclear energy sector—it is produced as a by-product in nuclear reactors and is also found in the radioactive waste of nuclear power plants.

Why must tritium be separated?

Currently, tritium separation technologies are being developed primarily for nuclear fusion applications. They are important both for the recovery and purification of tritium—for instance, from nuclear power plant cooling water—and for the fusion fuel cycle. This is crucial because the fusion process consumes only a small fraction of the deuterium and tritium; the unused fuel must therefore be separated and purified for reuse.

Tritium separation is also important for certain types of nuclear power plants—specifically fission reactors that use heavy water (water containing deuterium, or "heavy hydrogen," instead of ordinary hydrogen). Significant amounts of tritium can accumulate in the water during the operation of such reactors, necessitating its separation and purification for safety and efficiency reasons. Europe's first tritium separation facility is currently under construction in Romania.

Tritium separation technologies are also vital for environmental protection, particularly in the event of radiological accidents where large quantities of tritium could be released into the environment — as occurred following the 2011 accident at the Fukushima Daiichi nuclear power plant.

Separating tritium from ordinary hydrogen is challenging because the chemical and physical properties of these isotopes and their compounds are very similar. Consequently, complex and energy-intensive methods—such as cryogenic distillation or chemical catalytic exchange processes—are traditionally used for their separation. Although these technologies are effective, they require extensive infrastructure and significant resources.

Research at the University of Latvia

Scientists at the LU are investigating how membrane properties affect tritium separation efficiency during water electrolysis and how this process can be improved by incorporating nanomaterials into the membranes. This approach is unique because it enables not only more efficient isotope separation but also the creation of materials capable of operating under high-radiation conditions. Developing such solutions remains a significant area of ​​global research. Additionally, in collaboration with the Latvian company "Naco Technologies," catalysts for electrolyzers are being developed, and their impact on hydrogen isotope separation is being studied.

Nacos’ input in the project

Naco will use its vast knowledge and magnetron sputtering equipment to coat the necessary catalyst and protective coatings directly on the membranes and other electrolyser parts. Although role of catalysts is not the primary research objective in this project the impact is significant. Correct choice of materials and application conditions will make a difference in the outcome of the project. In this project Naco coatings will not only need to survive the already harsh environment dictated by the electrolysis processes but also withstand the damaging nature of tritium exposure.

In addition to fundamental research, the LU team is working with the company "Allatherm" on a prototype device designed for the efficient separation of tritium from water. The system combines an electrolyzer—where tritium is concentrated—with a fuel cell, allowing for the recovery of purified water and the simultaneous generation of electricity. Through this research, LU scientists are making a significant contribution to the development of sustainable energy by creating innovative technological solutions that could facilitate the safe and sustainable use of fusion energy in the future.

Project No. Project 1.1.1.3/1/24/A/122, "Development of polymer electrolyte membranes with carbon nanostructure additives for electrochemical tritium enrichment in fusion applications," is being implemented by the Institute of Chemical Physics of the University of Latvia in cooperation with SIA "Naco Technologies" and SIA "Allatherm".