Hot work: Oregon State to test mock reactors
Feb 15, 2013
By BENNETT HALL
Of the Corvallis Gazette-Times
CORVALLIS — A new test facility under construction at Oregon State University could pave the way for next-generation nuclear technology that would do double duty, not only generating electricity but also producing hydrogen for fuel cells.
Work is under way on a small-scale simulator of a very high-temperature nuclear reactor, known in the industry as a VHTR. The $4.8 million research project, funded by grants from the U.S. Department of Energy and the Nuclear Regulatory Commission, is expected to come on line in April.
Like other reactor simulators at OSU's Radiation Center, this one will be heated by electricity rather than uranium. The only nuclear-fueled reactor on campus is a 1.1-megawatt research model, which is considered too small to pose any sort of meltdown risk.
VHTR technology has been around since the 1950s but has not been widely adopted, said project director Brian Woods, an associate professor of nuclear engineering at Oregon State. Recent advances in materials science are prompting renewed interest.
“The base technology is not new,” Woods said. “What is new is the ability to use hotter temperatures.”
Measuring about 6 feet across and 18 feet high, the simulated reactor will be a 1/64-scale model of a commercial reactor. The mock reactor vessel will be fabricated from stainless steel with a ceramic core that mimics the graphite core of a working VHTR. Helium gas will be used as the cooling element.
Computer models suggest that VHTRs built with today's advanced materials could safely operate at temperatures up to 1,000 degrees Celsius (about 1,800 degrees Fahrenheit), roughly three times hotter than conventional water-cooled reactors.
Those high operating temperatures make VHTRs very efficient for spinning electrical turbines as well as a number of other uses, from providing process heat for industrial complexes to running water desalination plants.
But one of the most intriguing applications for these hotter reactors is the production of hydrogen for fuel cells, which offer the potential to power automobiles with zero emissions.
This green energy technology is currently limited by a number of factors, including the difficulty of producing large quantities of hydrogen. There are several methods of cracking water molecules to free the hydrogen atoms inside that require a major heat source, and high-temperature reactors could provide the heat without the need to burn fossil fuels.
“The optimal configuration would be to have a dual purpose,” Woods said. “During the day, when demand is peak, you generate electricity. At night, when demand is low, you switch over to hydrogen generation mode.”
VHTRs also have a number of safety advantages over conventional nukes.
For one thing, they produce only about half as much radioactive waste. For another, their design makes a meltdown impossible — the graphite core can withstand temperatures of 1,600 degrees Celsius, far hotter than the operating level, and won't sustain nuclear fission at that heat.
At least, that's the theory — and that's what the OSU simulator is designed to test. Woods and his students will put the mock reactor through all kinds of situations that might occur in a real-life accident to generate more realistic safety data. The information will be provided to the Nuclear Regulatory Commission, and Woods plans to publish his findings in scientific journals.
“The calculations we've done show that no matter how hot it gets, the core just can't get hot enough to melt,” Woods said. “That's our job, to run those accident scenarios and see what happens in our test reactors.”
When OSU's simulator is finished, it will be the only such facility in the United States and one of only a handful worldwide.
But it could have a short lifespan. The Nuclear Regulatory Commission funding for the project only runs through mid-2014. Unless follow-on funding is obtained, either from the federal government or a corporate partner interested in commercializing the research, it would likely shut down at that point.
“It will be a good facility,” Woods said. “It will be a shame if we don't get to use it quite a bit.”
Information from: Gazette-Times, http://www.gtconnect.com
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