An important step has been taken in the conversion of the Heinz Maier-Leibnitz Research Neutron Source (FRM II) at the Technical University of Munich (TUM) to low-enriched nuclear fuel: two fuel plates made of a monolithic uranium-molybdenum alloy have been successfully irradiated. This marks the first time a manufacturing process for new fuels with low-enriched uranium has been tested under realistic irradiation conditions.
Bernhard Ludewig / FRM II / TUM The French company Framatome manufactured the fuel plates as part of an EU research project in collaboration with TUM and other European partners. The irradiation test was carried out over two cycles in the BR-2 reactor at the Belgian research centre SCK CEN in Mol. The results show that the newly developed fuel plates can withstand the irradiation conditions that occur in the FRM II, a major success given that previously tested different materials had failed similar tests.
Licence application to be submitted in 2025
"The results confirm our strategy of switching to low-enriched fuel and are an important data point for the licence application that we will submit to the authorities later this year," says Prof. Christian Pfleiderer , Scientific Director of FRM II . "Our top priority is the safe operation of the research reactor. At the same time, our task as a major international research facility is to provide scientists from all over the world with neutrons for their research - for applications ranging from nuclear fusion to the production of radioisotopes for cancer therapy."
The design of the test and the manufacture of the plates are part of a development process that has been ongoing since 2019. "The collaboration between TUM and Framatome, supported by European partners, paves the way for a new generation of safe and efficient fuels for research reactors worldwide," says Ralf Gathmann, Vice President of CERCA at Framatome.
Legal framework
The development of new fuels for the FRM II is part of international efforts to convert research reactors to operate with less than 20 percent uranium-235. The operating licence for the FRM II also stipulates that the reactor must be converted as soon as a suitable fuel becomes available. Researchers at TUM have been working on corresponding concepts since 2003.
After an intensive testing phase, the decision was made in 2023 to use monolithic uranium molybdenum, as it can be packed particularly densely. "Since then, we have further developed the core design and, among other things, reduced the amount of fuel used. This maintains the scientific performance of the FRM II in the 60-day operating cycle," says Christian Reiter , Professor of Applied Nuclear Technology at the TUM School of Engineering and Design , who has scientifically proven the feasibility of a conversion.
