Research reactor FRM II in Garching
Photo: Peter Kneffel/ dpa
The FRM II research reactor in Garching near Munich is currently at a standstill.
Damage to the system has been repaired since 2020.
But the complex is supposed to start up again – and that's why there's a dispute.
It is about the question of which fuel the reactor is operated with and for how long.
So far, highly enriched uranium has been used as fuel in the FRM II.
That means: The proportion of the isotope uranium-235 in the fuel rods is 93 percent.
Nuclear opponents speak of weapons-grade material.
In fact, uranium with an enrichment level of at least 85 percent is used for nuclear weapons.
The critics are suing the Bavarian Administrative Court against the operation and are demanding that the fuel should only have an enrichment level of less than 50 percent.
New modeling now suggests that the FRM II can also be operated with low-enriched uranium.
Researchers from the Technical University of Munich (TUM) and experts from the USA came to this conclusion, the TUM announced on Friday in Garching.
She spoke of a "pioneering calculation".
This provides the theoretical basis for the implementation of the permit requirements in order to dispense with highly enriched uranium in the future.
In a complex study, Christian Reiter, reactor physicist at FRM II and head of the Theory Division at the TUM Center for Nuclear Safety and Innovation, calculated changes with his group.
The result: A fuel element with low-enriched uranium is physically possible for the FRM II and can be operated with the existing systems.
A major conversion of the neutron source is not necessary.
The new approval process is scheduled to start in 2025
Independent calculations at Argonne National Laboratory (ANL) in the US state of Illinois have confirmed the results of the TUM researchers, it said.
Reiter emphasized that, as a prerequisite for the calculations in his study, he was assuming that the new fuel would have to be licensable in Germany and that the new fuel elements could be manufactured with the proposed changes.
The study makes no statement about the actual technical feasibility of these conditions.
The reactor's operating license dates back to 2003. It stipulated that the plant should be converted to a lower-enriched fuel as soon as possible.
In 2020, the federal and Bavarian science ministries decided to decide on the fuel variant three years later - based on the research results available up to that point.
The new approval process is scheduled to start by 2025.