Research underway in a UH Cullen College of Engineering laboratory to make “heavy water” less expensively could soon make nuclear energy safer, eliminating real-life disasters like those that have occurred at the Fukushima and Chernobyl nuclear power plants.
It may seem impossible, but Stanko Brankovic, associate professor of electrical and computer engineering, Lars Grabow, assistant professor of chemical and biomolecular engineering and Ognjen Miljanic, associate professor of chemistry, have received a $400,000 grant from the National Science Foundation to make the impossible come true.
Their mission is to find a way to make heavy water, the coolant used in wet nuclear reactors, as accessible as, well, water.
Reactor safety: wet vs. dry
When it comes to nuclear energy and safety, it all boils down to the type of nuclear reactor that’s powering the plant. In the cases of Fukushima, Chernobyl and 66 percent of all nuclear reactors in the world, the reactors are classified as light water, or dry reactors. They use weapons-grade enriched uranium or plutonium as fuel, and their primary coolant is water. They are hard to control and can go supercritical, which means the nuclear chain reaction cannot be stopped and the reactor core can melt down.
On the other hand, no nuclear spills or emissions involving heavy water reactors, also known as wet reactors, have ever occurred. Heavy water nuclear reactors use either mildly-enriched uranium, which contains about 4 percent of the radioactive isotope, or natural uranium, which only has about 0.7 percent.
“The nuclear fuel used in a wet reactor cannot be used for a nuclear bomb, so proliferation of this technology to the world is a safe way of securing affordable energy for everybody,” said Brankovic. “Wet reactors cannot go supercritical, and their operation and control involves less risk for nuclear pollutant emission.”
The heavy water used as coolant in wet reactors is made with a heavy isotope of hydrogen; this kind of water is literally heavier than the H20 that runs out of our water faucets.
For every 10,000 molecules of regular water, only one molecule will actually contain an element known as deuterium which, with oxygen, makes a D2O, or deuterium oxide. This is the heavy isotype of hydrogen, or the heavy water so in demand.
With something as rare as D2O, the cost to separate it far surpasses the cost of enriching the nuclear fuel or making plutonium. That’s why the wet reactors are less popular, even though they are much safer.
“Therefore, making the heavy water more affordable will make safe nuclear energy more affordable and more widespread across the United States and world,” said Brankovic.”
Breaking up is hard to do
In life and with water molecules, separation doesn’t come cheaply. “But if we can have a catalyst that is more efficient in separating D2O from regular water, we’re saving energy, which means the price of the heavy water will go down and wet reactors will be more financially beneficial,” said Brankovic.
Brankovic is no stranger to the catalyst design business. In 2001, he was highly cited for his work on creating a catalyst for fuel cells, the kind that ultimately brought us the electric car.
The catalysts Brankovic, Grabow and Miljanic are making are special strained platinum and palladium monolayers that will increase the strength of the adsorbed hydrogen bond, leading to better isotope separation efficiency.
Nuclear safety and world peace?
“Safe nuclear energy is one of the solutions to many of the world’s problems,” said Brankovic. He talks about a world where more wet nuclear reactors are online using the heavy water that he will create so inexpensively. Those reactors will also be using natural uranium.
“The whole problem now is that you don’t know if anyone is enriching uranium for their reactors to produce electricity or because they want to make nuclear bombs,” said Brankovic. “How do you police this?”
He thinks there is one certain way. By using heavy water reactors and providing methods to collect enough heavy water affordably. When heavy water is plentiful, dry reactors will no longer be needed and neither will the enriched uranium or plutonium used to make nuclear bombs.
“Ideally we can make the world a safer place,” said Brankovic. That global safety may one day be traced back through Brankovic and team to the UH Grants to Enhance and Advance Research (GEAR) program, which provided funding as they were preparing grant proposals.
“This allowed my colleagues and me to create a competitive proposal that will lead to breakthrough research,” said Brankovic.