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July 14, 2011

Could Thorium solve the world's energy problems?

Nuclear technologist Kirk Sorensen has spent much of his career researching the potential of thorium fission reactors. Sorensen has recently founded a company, Flibe energy, which is dedicated to developing small, portable thorium power plants. In an interview with Sander Olson (exclusively for Nextbigfuture.com), Sorensen discusses why he believes that thorium could be used to meet all of the earth's future energy needs, and how thorium reactors could eventually produce electricity for a penny per kilowatt hour.

Kirk Sorensen indicates that he is confident to have sufficient funding to have a prototype thorium reactor by 2016.

Kirk Sorensen

Question: How did you first find out about Thorium reactors?

I had just finished grad school, and was working with a group at NASA that does advanced technology work. I read a book on advanced nuclear reactors, and did some web research. I discovered that Thorium reactors have the potential to effectively solve the world's energy requirements.



Question: How does Thorium compare to fusion reactors?

I originally was a big proponent of fusion power. But I took a class on fusion power, and came to the conclusion that the concept was never going to be commercially viable. In fusion, the laws of physics are a serious problem - charged particles do not want to fuse. They want to scatter. I knew a physics professor who was an expert on both fission and fusion, and he noted that fusion requires hundreds of PhDs working for decades, and we still don't fully understand it. By contrast, fission is so simple that high school students can be trained to run the reactor. I follow the various proposed fusion schemes, and I don't think fusion will ever be economically advantageous.

Question: How would a thorium reactor stack up against a conventional fission reactor?

For thorium utilized in a LFTR, thorium has compelling benefits over conventional uranium light water reactors. LFTR has the benefit of operating at high temperature but low pressures. That obviates the need for 9 inch steel pressure vessels, and thick concrete containment structures. Everything gets smaller with Thorium and fluoride salts, and that provides a substantial economic benefit.

Question: What about safety, reliability, and simplicity of operation?

A properly designed LFTR approach would be inherently safer, simpler, and more reliable than conventional fission reactors. Thorium reactors will incorporate a "freeze plug" at the bottom made of the vessel, made from fluoride salt. So if a reactor loses all power, the plug melts, and the core drains out into a passively cooled drain tank. That is something that cannot be done with solid fuels. This passive approach is inherently safer than the active safety measures used in light water reactors.

Question: How extensive are thorium deposits?

Although I'm not a geologist, thorium is actually a surprisingly abundant substance. Thorium is found in the vicinity of rare earth elements, and rare-earth prospectors are practically willing to give thorium away for free. So we have enough thorium to last for centuries, if not longer.

Question: Can Thorium reactors be scaled up to gigawatts?

Yes, the LFTR technology if very favorable to scaling. We could scale down to a megawatt, or up to gigawatts. The real challenge will be getting to the first unit.

Question: What is the anticipated cost per kilowatt-hour?

Although we don't have hard data on this yet, we anticipate that Thorium reactors will provide electricity for less cost than any other competing solution. I think that it is feasible to eventually get to 1 cent per kilowatt hour using this technology.

Question: When could the first prototype Thorium LFTR come online?

The first reactor could come online within five years. To do this, we would need several hundred million dollars for engineering R&D and military regulatory authority backed by a strong need. The first LFTR will probably only be designed to operate for perhaps a decade. The advantage of the salts we use is that the salts can be easily reused.

Question: Can any of the parts of the reactor besides the salts be recycled?

Our ultimate aim is to get reactors that are completely recycled. We plan on making mobile units which can be taken back to the factory and disassembled. The salts would be removed and recycled, as well as the graphite core. We believe that the goal of a nearly entirely recyclable thorium reactor is feasible.

Question: How does the burning of thorium in a LFTR compare with the burning of uranium in a light water reactor?

In a conventional light water reactor, only a tiny portion of uranium - less than 1% - is consumed. By contrast, we are shooting for 99% consumption of thorium. The small amount of actinide that remains will be an extremely valuable byproduct, since it be primarily plutonium 238. Plutonium 238 is used by NASA to power its deep space probes.

Question: Could Thorium be used to power spacecraft, or ships?

I have done research into that subject, and came to the conclusion that it is feasible. Although nuclear is unsuitable for getting into space from earth, thorium could be used for deep space missions. A thorium powered ship makes a lot of sense, and I can foresee future cruise ships and cargo vessels with thorium reactors.

Question: Are you confident that you will be able to find a source that will provide the necessary funding?

Although I am not at liberty to discuss specifics, I am confident that we will be able to garner sufficient funding to have a prototype thorium reactor in operation within five years.

Question: Could thorium reactors be used in population centers?

Yes, putting these LFTRs near populated areas is an excellent idea. By placing reactors near population centers, you minimize transmission losses and can utilize waste heat for district heating.

Question: How has the mainstream nuclear community reacted to the concept of thorium LFTRs?

Although technical objections have been raised in the engineering community regarding the viability of thorium reactors, the physics is well proven. There exist a plethora of engineering challenges, and these need to be addressed. The nuclear community is not particularly receptive to the concept, but I think this is due in large part to their solid-fueled paradigm.

Question: Are there any specific objections raised by the technical community?

The biggest objection I hear is that the problem is too hard and will take too long. I strongly disagree, and I have staked my career on the viability of thorium as an energy source.

Question: Can you envision any other energy source competing with thorium?

I have examined a number of energy proposals, and I cannot see any other technology effectively competing with thorium utilized in a LFTR. Thorium is vastly superior to any other approaches, including solar, wind, geothermal, and fusion.

Question: When could we see the first utility class thorium reactor?

Given sufficient funding, we could see a utility class gigawatt reactor up and running within ten years. It will probably be a prototype, verifying the concept and accumulating operational experience. Within twenty years, we could have multiple factories producing hundreds of thorium reactors each. If that happens, we could see new thorium reactors being produced on a daily basis. At that point, it wouldn't be long before thorium reactors provide all of the earth's energy needs.







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