Could better cladding on nuclear fuel rods prevent potentially catastrophic leakage when they are exposed in a reactor accident?
That is the focus of research now underway at the University of Texas at Dallas.
Photos: University of Texas - Dallas
“We need to understand how the material behaves
under extreme pressure, temperature, corrosion
and irradiation,” says Dr. Hongbing Lu.
As Japan continues to grapple with its nuclear crisis, Dr. Hongbing Lu is studying how new nanocoating materials might help prevent future cracks in stressed fuel rods and other areas of nuclear reactors.
Lu, a nanomaterials expert with the Erik Jonsson School of Engineering and Computer Science, has been working since last July on the project, underwritten by an $875,000 grant from the Department of Energy.
A microscopic photo image shows contour lines
denoting stress near a propagating crack on
the surface of a nuclear fuel rod.
And while the original goal was to reduce nuclear waste and improve efficiency of the rods, the research could also have safety implications for rods and reactors.
The first phase of the research involves studying material behavior under the stress of a reactor environment.
To that end, Lu is working to simulate the cracks that form in the metal-alloy surface, or cladding, of nuclear fuel rods.
These cracks develop in the stressful reactor environment of tremendous heat, corrosion, irradiation and pressure. They are microscopic in size but can cause a reduction in the fuel burn-up rate, decreasing power station efficiency and increasing nuclear waste.
How Material Behaves
“We’re working on a very general simulation methodology that can be applied to that kind of environment,” Lu said. “It’s more than just crack growth. We need to understand how the material behaves under extreme pressure, temperature, corrosion and irradiation.
“With the methodology we’re using, we’re taking all of those factors into consideration and incorporating material behaviors into some mathematical models to describe them under very complicated conditions.”
Lu and his team are generating data about the effects of pressure and temperature, factoring in DOE information about fission and other labs’ information about the effects of corrosion.
The second step will be hands-on experimentation with nanomaterials, Lu said.
“Once we’ve gathered all of the information on nuclear fuel cladding in that environment, then we’ll be able to plug it all into a simulation code and develop a better understanding of how quickly the cracks grow,” he said.
“At that point, we can go beyond the simulations and begin working on actual materials tested in the government labs.”
The goal is improved cladding material for fuel rods—and perhaps better protective coatings for the rest of the nuclear industry.
“The same simulation methodologies we’re developing can be applied to other parts of a nuclear power station,” Lu said.
“Take the pressure vessels, for instance. The environment may not be as extreme as in the fuel cladding —the temperature and radiation may be lower—but, overall, the two environments are very similar. And if you remove the radiation, you can apply the methodologies to other high-pressure environments such as engines.”
Lu has said that he hopes to assuage people’s concerns about nuclear power, which—at least, until the Japan disaster—has been gaining in popularity, especially in China, India and Europe.
“With the use of modern technology, nuclear energy is really safe,” he said last summer. “It’s quite different from many decades ago. The nuclear physics has already been figured out. Other things are dictating the efficiency of the fuel burn-up. You need people from all disciplines. My contribution has to do with the mechanics and materials aspects of the nuclear fission process.”
Lu holds the first endowed chair at UTD’s Department of Mechanical Engineering. He was unavailable for comment Wednesday (March 16).
Warning on ‘Scaremongering’
Meanwhile Wednesday, British scientists warned against “scaremongering” over the Japan crisis and panic buying of potassium iodide tablets.
Experts at the Royal Society of Chemistry in Cambridge, UK, cautioned against hysteria over the effects of the explosions at the Fukushima nuclear plant, saying that comparisons with the 1986 Chernobyl disaster are unfounded.
U.S. drug stores have reported a sharp surge in potassium iodide sales, with “panic buying” due to developments in northeast Japan, RSC says. One drug supplier says it has sold 250,000 anti-radiation pills to Americans in recent days.
But Americans have no need to stock up on potassium iodide tablets, said Dr. Brian Carter, the RSC’s environmental sciences program manager.
He called it “highly unlikely” that radioactive iodine from Japan could “cause a problem in the United States or anywhere else. …”
“The current situation is not of the same scale as the Chernobyl disaster,” Carter said
He said the jet stream could carry some radioactive iodine to the United States if blown by a major explosion into the upper atmosphere, but “it is unlikely that it would be at the level requiring extensive dosing using potassium iodide tablets.”
For now, only people in and around Japan’s exclusion zone need tablets, Carter said. “Supply is incredibly unlikely to be an issue, provided that people are not driven into buying and using the pills by scaremongering.”