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GA Researching More Efficient Nuclear Reactor

The U.S. Department of Energy said recently that General Atomics will receive federal funds to develop advanced nuclear reactor technology.

La Jolla-based GA will enter negotiations with the government and expects to come away with about $1 million to investigate a new material for nuclear fuel rods.

That is according to John Parmentola, senior vice president of GA’s Energy and Advanced Concepts Group.

The research dovetails into a more ambitious GA nuclear reactor project, called EM².

In the government-funded work, GA proposes to use a composite material called silicon carbide to encase uranium in nuclear fuel rods. The conventional way to make a fuel rod is to package uranium pellets in something different: a zirconium alloy tube.

The work on the new type of fuel rod will be done over two years, and GA must agree to pick up at least 20 percent of the project costs.

Silicon carbide can withstand much higher temperatures than conventional zirconium alloys, Parmentola said, so adopting the technology would open the door to reactor designs that are different from the conventional water reactor.

The Energy Department made four awards totaling $3.5 million to companies investigating nuclear reactor technology that goes beyond “traditional light water designs.”

Three Other Recipients

The three other recipients are GE Hitachi Nuclear Energy of Wilmington, N.C.; Gen4 Energy of Denver; and Westinghouse Electric Co. of Pittsburgh, Pa.

The projects will address various technical challenges to designing, building and operating the next generation of nuclear reactors, said a statement from the Energy Department. “These steps support the president’s plan to cut carbon pollution and spark innovation across a wide variety of energy technologies including emerging nuclear technologies,” the statement said.

Technologies to be explored include Gen4’s use of two metals — lead and bismuth — to cool reactors. Russian scientists have built lead-bismuth reactors.

GA’s work will look at the nature of ceramiclike composites.

‘Support Future Licensing Efforts’

“Better understanding of silicon carbide composite material will help incorporate this material into advanced nuclear reactor designs and support future licensing efforts,” said the statement from the Energy Department.

Composite materials such as silicon carbide have proven useful in aerospace, Parmentola said. Experimental supersonic combustion ramjets, or “scramjets,” have hit or exceeded speeds of Mach 5 — five times the speed of sound. The aircraft have to operate at very high temperatures, so engineers have had to use composite materials, Parmentola said.

The nuclear industry could likely use something that stands up to heat.

Right now the industry operates large, very complex reactors. They are costly, Parmentola said. The reactors’ steam turbines, which generate electricity, operate at only 33 percent efficiency, he said.

Fuel is depleted relatively quickly.

Parmentola, who holds a doctorate in physics from the Massachusetts Institute of Technology, said the nuclear industry needs to make reactors smaller and more efficient in order to move ahead. “You have to conquer both (challenges) or you’re not going anywhere,” he said.

Size of a School Bus

GA may have an answer to the problem in its EM² reactor, the executive said. The abbreviation stands for Energy Multiplier Module.

The proposed reactor is the size of a school bus, can be produced in a factory and trucked to its site over the public highway system, Parmentola said.

The typical steam-producing reactor operates at 275 degrees Celsius. The EM² reactor operates at much higher temperatures, at 850 degrees Celsius. Instead of water, it uses helium gas to cool the reactor. Helium also runs a high-speed gas turbine to generate electricity.

The design could wring 48-53 percent of the energy from its nuclear fuel, the scientist said. The latter would be a 60 percent improvement over conventional technology.

The heat of the helium reactor poses a problem, however. Many metals can’t withstand a temperature of 850 degrees Celsius. So engineers need to replace metal with a silicon carbide composite — the subject of the government-funded study. Silicon carbide breaks down at about 2,700 degrees Celsius.

‘Very Safe’

The EM² reactor is “very safe,” Parmentola said, adding that it could burn material that is now considered nuclear waste (not to mention depleted uranium — the material left over after the refining process). GA says that the United States has the equivalent of 9 trillion barrels of oil locked up in its inventory of used nuclear fuel alone.

Developing the EM² reactor will require significant amounts of money. Tests would have to be conducted at Department of Energy labs, and that kind of testing is very expensive, Parmentola said.

But it could one day produce a rewarding, efficient reactor, the scientist said.

And it would be better than business as usual.

Use of conventional, light water reactors is akin to running a sawmill, selling the sawdust and throwing the boards away, Parmentola observed.

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