Faced with a lack of fresh fuel for nuclear research reactors, the Department of Energy has dug into its inventory of used fuel to keep the University of Maryland’s reactor operating at top efficiency. The fuel, which had been stored at DOE’s Idaho National Laboratory, was delivered to the university in March.
The shortage is due to the temporary shutdown of TRIGA International in France, which is the sole manufacturer of fuel for reactors of the type installed at Maryland. Research reactors, whose primary function is the production of neutrons for experiments, require far less fuel than power reactors but a much higher level of uranium-235 enrichment—up to 20%, compared with 3–4% for generating energy.
Without fresh fuel, the Maryland reactor’s core has been producing about 20% less power than its 250 KW capacity, says Timothy Koeth, director of the university’s radiation facilities. Because fission products known as poisons build up and absorb neutrons, the reactor can be operated just twice a week for eight hours at a time. The reduced neutron flux means experiments have had to run longer, with heightened noise relative to signal.
Not all the fuel will be replaced, and Koeth says that modeling is currently under way to determine which of the old fuel elements will be swapped with the slightly irradiated fuel. The refueling process, which requires licensing by the Nuclear Regulatory Commission (NRC), could take a year to complete.
Nuclear regulators ordered the French fuel facility’s hiatus for safety and security upgrades that are expected to be completed in 2019. DOE, which has committed $10 million toward the $32 million upgrade cost, will receive top priority when the first shipments become available in 2020 and will pay a reduced price for the fuel. The agency retains ownership of the fuel, supplies it to university reactors, and disposes of the used fuel at no cost to institutions.
The University of Maryland is one of 11 US universities with a Training Research, Isotopes, General Atomics reactor, better known as a TRIGA reactor, and eight of those can handle the 400 slightly irradiated fuel elements stored in Idaho. That’s enough to keep all the reactors operating throughout the shortage, a DOE spokesperson said. The fuel shipped to Maryland is virtually indistinguishable from new fuel, Koeth says, as it contains 99% of its original fissionable content.
In December 2016 the 44-year-old Maryland reactor had its operating license renewed for 20 years by the NRC, which also approved the DOE supply initiative. Koeth says the reactor is used for training operators and other nuclear-related workers. It is also used for research, mainly neutron radiography. One PhD student is studying the degradation of antiquities by using neutrons to examine Italian stone that has been eroded by water and acid rain. The goal is to find coatings at the atomic level that could preserve the surface of an artifact without affecting aesthetics.
“This partnership between DOE and the university will enable students to continue their education in nuclear energy while also putting an existing fuel source to good use,” said Raymond Furstenau, DOE’s acting assistant secretary for nuclear energy.
