Nuclear energy requires lots of heat and might get even hotter.

Increased heat is part of what makes a new type of reactor so promising. But it's not only the way the heat is used, but also the way it is safely contained that leads some to believe that Molten Salt Reactors, or MSRs, will play a major role in reducing or even freeing the U.S. from its dependence on fossil fuels for electricity. 

The most recent display of optimism comes in the form of a $40 million grant awarded by the Department of Energy to Southern Co. -- which already operates a fleet of conventional nuclear plants throughout the South -- to develop what the company calls a Molten Chloride Fast Reactor, which is a type of MSR. 

In an MSR, the nuclear fuel that is put into the reactor is immediately dissolved in the salt and continuously circulated, creating non-stop fission. The reactor also operates at a much higher temperature than conventional reactors (about 700 degrees Celsius vs. 200 degrees Fahrenheit), which is made possible because the salt has a far higher boiling point than coolants traditionally used in reactors, such as water.  

It is unclear how many other companies applied for the grant, and both the DOE and Southern declined to provide a full copy of the company's grant application, saying that it contained sensitive proprietary information. But a spokesman for the DOE said that Southern had offered to fund 40 percent of the cost of the project -- the department wanted applicants willing to pay at least 20 percent -- which will take place at a DOE laboratory in Oak Ridge, Tennessee, and will include collaboration from another nuclear energy firm, TerraPower, along with the nonprofit Electric Power Research Institute and Vanderbilt University. 

Steve Kuczynski, the chief executive of Southern Nuclear Operating Co., the division that will be leading the project, said he envisions a multi-year research and development process that will hopefully culminate in a commercially viable product by around 2030. 

Kuczynski said he believes the technology could be a game-changer in a number of ways. 

"There's an opportunity to use the heat from this reactor not just to generate electricity but other things, like generating hydrogen or desalinating water or selling it to industry," he said. 

Payment of the full $40 million is not guaranteed unless the DOE is satisfied with the project's progress at various stages. The agency said it set aside $6 million for 2015 to be split between Southern and X Energy, a startup that was similarly awarded a $40 million grant to develop a pebble bed modular reactor. That will be followed by $12.5 million in fiscal 2016, but funding in following years is contingent on results of the research.

What makes molten salt reactors truly revolutionary, explained Erich Schneider, an associate professor of nuclear engineering at the University of Texas at Austin, is that they will be able to use almost all of the nuclear fuel put into them. That contrasts with conventional reactors which typically only use about 5 percent of the fuel before the fuel rod has to be taken out and disposed.

"The other 95 percent we kind of don't know what to do with it," he said. "There are parts that remain radioactive for millions of years."

But in an MSR, he added, "You can leave the fuel in there until it's entirely used up." 

That not only suggests that nuclear power could become much more efficient and economical, but far safer. Instead of generating large amounts of extremely hazardous unused fuel, MSRs generate a far less radioactive residue that is only hazardous for several hundred years. 

That's a big improvement over the assurances from officials that any waste stored at some point at, say, the Yucca Mountain Nuclear Waste Repository in Nevada, would be safely contained for at least 10,000 years, a timeframe that Schneider points out exceeds recorded human history. 

"I can say as an engineer that we can build a facility that can keep that waste safe and totally isolated from harming anybody for 300 years," he said. "But 10,000 years -- it almost becomes a philosophy debate. It's outside the human context." 

Like most other reactors these days, the MSR has a "negative temperature coefficient" that automatically shuts down the reactor if temperatures get too high. But what promises to prevent Fukushima-style disasters, said Schneider, is that the salt in which the fuel is mixed keeps it cool even after the reactor shuts down. 

While environmental groups with close ties to Democrats, including the Sierra Club and the League of Conservative Voters, have historically opposed nuclear power as an unacceptable compromise between fossil fuels and renewable energy, the Obama administration clearly sees a future role for nuclear in the economy. 

"I think the administration has been very consistent that they believe through their actions that nuclear has to remain a part of our portfolio," said Kuczynski. 

Affirming as much, a statement from a DOE spokesman included the following note: "As the nation's largest source of clean electricity, nuclear energy is an important part of the solution to the nation's energy challenges."

Schneider, who collaborates with researchers at the Massachusetts Institute of Technology on efforts to develop MSRs, believes the technology means that nuclear could replace natural gas as the dominant partner of renewable sources, such as wind and solar. 

"What I'm really interested in is moving toward synergy between nuclear with the renewables, because the renewables can't do it alone," he said. 

For now, however, conventional nuclear power plants, which are expensive to build and maintain, aren't an economical alternative to natural gas, especially now that it's so cheap. Also, nuclear reactors stay running 24/7 and lose money when the wind is blowing hard and there is no demand for additional energy from the grid. 

Hopefully, said Schneider, a new generation of nuclear power plants that are much cheaper to build and present far fewer safety headaches will be able to knock carbon out of the electricity game entirely. That, in turn, could make electricity an even more attractive solution for powering transportation, ultimately reducing or eliminating our dependence on petrol.  

"It's hard to get to a low or carbon free economy without nuclear," he said.  

 

http://www.energybiz.com/article/16/02/southern-explores-potential-molten-salt-reactors