Fuel-cladding research yields results
fter two years of study, engineering physics researchers learned enough about gadolinium, a material commonly used to “eat” neutrons during a reactor power-up, that they crossed it off their list of candidates for coating the zirconium tubes that hold a reactor’s fuel. During power-up, the uranium-dioxide fuel pellets emit a blast of neutrons that passes through the zirconium tubes’ walls. Boron or gadolinium mixed with the pellets helps diminish the neutron blast; however, the mixing process is costly, heavily regulated and detrimental to the fuel’s efficiency.
Working with Westinghouse Corporation and Sandia National Laboratories, Senior Scientist Kumar Sridharan and Associate Scientist Mark Anderson tested a method to take the boron or gadolinium out of the fuel pellets and place it into the outer surface of the zirconium tubes.
The two successfully alloyed the gadolinium and boron onto zirconium using a high-energy ion blast. But when the researchers tested each material to see how it responded under reactor-like conditions, the gadolinium-alloyed zirconium corroded substantially.
The boron on zirconium, however, passed
with flying colors, says Sridharan. “Boron did not corrode at all in the autoclave tests,” he says. “So thats a real success story.”
With extended funding via the U.S. Department of Energy’s Nuclear Energy Education Research program, he and Assistant Professor Todd Allen will expand the substrate material from zirconium to ferritic martensitic and austenitic steels. “Another addition to the work will be the radiation testing,” says Sridharan, “because after all, we want to see how these alloyed layers behave under radiation.”
With collaborators at Idaho National Lab, the two have started radiation-testing the boron-alloyed zirconium at the lab’s reactor facilities.