TerraPower, the Bill Gates-chaired nuclear company that is developing a fast reactor, is now investigating alternative reactor technologies, including thorium fuel and molten salt reactors.While the company’s “big bet” continues to be on a fast reactor that TerraPower calls a traveling wave reactor (TWR), it is exploring other designs that could offer improvements in safety, waste and economics, CEO John Gilleland told me in a phone interview.“We are an innovation house, so we like to look at other approaches,” Gilleland said. “Our big bet is on the traveling wave reactor because it fulfills so many of the goals that we would like to see nuclear achieve. But we’re always looking for innovations that lead to better safety or minimization of waste and so forth and so we have several things going there. Although those activities are small, that’s the way large activities get started.”TerraPower’s interest in alternatives such as molten salt reactors (MSRs) came to light last month when the company’s director of innovation, Jeff Latkowski, surfaced in the audience at the Thorium Energy Alliance Conference in Chicago. The two-day gathering included presentations on thorium fuel and on reactors including molten salt reactors, high temperature solid fuel reactors, accelerator driven reactors, and others.Latkowski quietly joined the five-year-old Bellevue, Wash., company a year ago to look after alternative approaches to nuclear. “My job at TerraPower is everything outside the Traveling Wave Reactor,” Latkowski told me in an email exchange after the Chicago event.MSR WITH A PROPRIETARY TWISTThat includes MSRs, the design known by its enthusiasts to efficiently and safely produce high temperature heat for electricity generation and for industrial processes. MSRs use liquid fuel that cannot melt down and that harmlessly drains into a holding tank in the event of an emergency. They operate at atmospheric pressure rather than at potentially dangerous high pressures associated with conventional reactors. MSRs augur improvements in waste and a reduction in weapons proliferation threats, especially if they run thorium fuel. Tennessee’s Oak Ridge National Laboratory built an experimental version in the 1960s, under the direction of Alvin Weinberg.Another benefit for MSRs, as Gilleland noted, is that “your fuel is not as susceptible to the sort of neutron damage that other approaches are.” In other words, MSRs have a much higher “burn up” – they make greater use of fuel – than do conventional solid fuel reactors.“We’re thinking about it and trying to work on it and we have a few proprietary ideas that we’re cooking up,” Gilleland said in relation to MSRs. He did provide details of the “proprietary” ideas, noting that, “We like to work on an idea for a while before we run out and tell about it – so we have some ideas which we’re trying to ferret out how good they are.”Director of innovation Latkowski declined to say whether or not TerraPower has filed any MSR patents. In addition to running innovation and related partnerships, Latkowski also “oversees the development, maintenance and protection of TerraPower’s intellectual property portfolio” according to his company bio. TerraPower is a spin out of Intellectual Ventures, an innovation and venture capital firm that makes a business out of patents and is known as a keen collector and protector of intellectual property. It is headed by Nathan Myhrvold, a former Microsoft chief strategist and technology officer who serves as TerraPower’s vice chairman.
I asked CEO Gilleland about the extent to which TerraPower bases its MSR ideas on the Oak Ridge design. “Oh everybody goes back to that as a good reference point, and we have considerable departures from it that we’re thinking about,” he said. “So we’re just having a lot of fun with it. That’s how you get good ideas.”According to Gilleland, MSRs still face technological hurdles, including the avoidance of corrosion in the reactor materials. He also said that TerraPower would want to assure that an MSR could reprocess fuel without having to remove it. Any removal increases proliferation possibilities of waste falling into the wrong hands. (One of the strong suits that TerraPower claims for its TWR is that, unlike other fast reactors, the TWR does not require the expensive and potentially hazardous removal of spent fuel to reprocess into usable fuel).“We prefer a system where you can leave fuel in the reactor for a long time,” he noted.THORIUM TOOTerraPower is also investigating the possibility of deploying thorium, a fuel that Gilleland said could trump uranium by virtue of thorium’s wider availability. There is about four times more thorium than uranium in the world.But Gilleland noted that the attributes of TerraPower’s TWR fast reactor could offset any need for thorium. The TWR is the design that TerraPower has proposed for converting depleted uranium into plutonium that would burn for about 60 years before requiring refueling. It is a type of fast reactor – a reactor that does not slow down or moderate neutrons as today’s commercial “thermal reactors” do.What about other nuclear technology alternatives, such as high temperature solid fuel reactors?“We’re looking at all of them,” said Gilleland. “There’s no one at the top of our list right now.”He described Latkowski’s innovation initiative as a “skunk works” that’s not a formal division but rather is a framework for encouraging lateral thinking. He likened it to innovative information technology companies that facilitate free thinking time for employees.“It’s like Google and other places – the best ideas sometimes came from the person doing the backstroke in the swimming pool, or at home thinking,” said Gilleland. “So we want to just make sure that people have a certain fraction of their time for free thinking.”FORGET THE FUSIONOne nuclear technology that TerraPower most likely won’t be pursuing is fusion.“I have a soft spot in my heart for fusion, having run the ITER program and things like that, but it’s something I can’t count on for my grandchildren,” said Gilleland, whose background includes having served as U.S. managing director on the International Thermonuclear Experimental Reactor (ITER), based now in Cadarache, France. Innovation director Latkowski also comes from a fusion background. Before joining TerraPower last year, he was chief scientist on the commercialization program at the National Ignition Facility, the U.S.’s massive laser fusion project at Lawrence Livermore National Laboratory in California.“We’re focused more on fission rather than fusion,” Gilleland said. “Fusion just takes so much more development and so much more time.” Other companies, like General Fusion, Helion Energy, Lawrenceville Plasma Physics, Tri-Alpha Energy and Lockheed Martin might disagree.So how real are the company’s fission possibilities outside of the TWR?“If we do things right , we’ll have some interesting things to talk about,” he said.His interest in broadening nuclear development at TerraPower echoes remarks made in the past by TerraPower chairman and software billionaire Gates. In a 2010 presentation at the Massachusetts Institute of Technology, Gates pointed out that “nuclear innovation stopped in the 1970s”and encouraged the industry to move to alternative nuclear technologies.Gilleland described reactors such as the MSR as “futuristic” compared to the traveling wave, noting the TWR will come out first. The company thinks the TWR can be ready by the mid-2020s.STOP CHASING THE WAVEDevelopment work and partnerships on the TWR are progressing, and TerraPower has already made a notable design change. AlthoughTerraPower still refers to its reactor as a “traveling wave,” it has turned it into more of a “standing wave” design.In a TWR, first proposed in the 1950s, a cylinder of depleted uranium burns slowly like a candle, breeding plutonium (in a breeding “wave”) which fissions and produces heat. But as the World Nuclear Association notes, TerraPower has, “changed the design to be a standing wave reactor, since too many neutrons would be lost behind the traveling wave of the previous design and it would not be practical to remove the heat efficiently.” (TerraPower’s design calls for removing heat with a liquid sodium coolant).In the new standing wave design, the fission reaction starts “at the centre of the reactor core, where the breeding wave stays, and operators would move fresh fuel from the outer edge of the core progressively to the wave region to catch neutrons, while shuffling spent fuel out of the centre to the periphery,” WNA explains.As Gilleland put it, “We decided to have the fuel move past the wave rather than have the wave move past the fuel.” (The neutron loss might help explain why Gilleland is attracted to the MSR’s tendency to avoid neutron damage).“It’s basically the same physics of what we started out with,” he said. “It’s just the practical considerations associated with making the most use of every neutron, and the engineers’ love of keeping the cooling system in one place, and not chasing the wave. It didn’t set us back at all. It was just sort of a natural evolution and one of the variations on the theme we’d been studying all along and then we just finally decided to switch to this standing wave. It just made some things easier.”TerraPower believes it can start up a 600-megawatt prototype reactor by 2022 and have its first fast reactor ready for deployment by the mid-2020s. To that end, it has entered development partnerships with many international and domestic research groups and companies. The partners include several outfits in Russia, a country that is emphasizing fast reactor development: state nuclear company Rosatom and its TVEL fuel group; the Scientific Research Institute of Atomic Reactors; and A.A. Bochvar High-technology Research Institute of Inorganic Materials.In China, TerraPower has teamed with the China Institute of Atomic Energy, which is developing a fast reactor. Other partners include the Korean Atomic Energy Research Institute, Japan’s Kobe Steel. Domestically, TerraPower is working with, among others, MIT, the University of California Berkeley, Oregon State University, the University of Michigan, Texas A&M University, the University of Nevada and a number of private companies. For a full list see TerraPower’s “partners” page.It will be interesting to see if any MSR partners begin to appear on the website.Photo of Bill Gates talking about nuclear and the environment at a 2010 TED talk is by Steve Jurvetson, via TED and Flickr. Photo of Nathan Myhrvold is a screen grab from a TerraPower video via New America Foundation and YouTube.—NOTE: This version corrects an earlier one that stated the TWR performs online reprocessing. It does not. Its fuel does not require reprocessing. Not only does it not have to remove fuel for reprocessing – an advantage over other fast reactors – it does not have to reprocess at all.. Also, Jeff Latkowski was chief scientist for NIF’s commercialization program, called Laser Inertial Fusion Energy (LIFE), not for all of NIF as originally stated. Corrected July 24 at 3:10 p.m. UK time.