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Posted by Mark Halper

Motoyasu Kinoshita NRKno

Moto-yasu Kinoshita speaking in Norway in 2011. Kinoshita hopes to run molten salt fuel tests at Norway’s Halden reactor.

Japan’s fleet of conventional nuclear reactors remains mostly shut following the Fukushima meltdowns two years ago but a significant aspect of it lives on – its high level nuclear waste.

One company has a plan that would use that waste for fuel in an altogether different type of reactor and thus turn Japan’s troubled nuclear past into a revived future.

Tokyo-based Thorium Tech Solution (TTS) wants to combine the reactors’ waste – their spent fuel full of actinides like plutonium – with thorium, the element that many people believe makes a superior alternative nuclear fuel to today’s uranium.

And rather than use the fuel in conventional solid rod form, TTS would put it into a liquid, molten salt form. TTS’ molten salt reactor (MSR) would thus deliver the classic advantages of an MSR, while also helping Japan deal with its nuclear waste. Compared to conventional solid fuel uranium reactors MSRs are safer, cannot melt down, generate less long-lived dangerous and weapons-prone waste, and are more efficient. All the better if they use thorium instead uranium, many believe.

TTS, founded by the late Dr. Kazuo Furukawa, bases its designs on the work of Dr. Alvin Weinberg, who built a thorium MSR in the 1960s at Oak Ridge National Laboratory in Tennessee.

Furukawa started TTS in 2011, soon before his death in December of that year at the age of 84. TTS picked right up where his previous company, ITheMS (International Thorium Energy & Molten Salt Technology Inc.) left off. It aims to build a 160–megawatt electric MSR called a FUJI, and a smaller 7-megawatt model called a miniFUJI (in this case, the word “fuji” implies “the only one” – as in the only solution for a carbon free energy future).

ITheMS, which was run by Japanese politician Keishiro Fukushima with Furukawa as its chief scientist, closed in 2011 after it was unable to secure $300 million it had sought.

MOLTEN IN THE BLOOD

Furukawa, who devoted much of his career to molten salt nuclear research (in the early1980s he worked on an accelerator-drive molten salt system before shifting to the Oak Ridge design), was steeled on making TTS the success that ITheMS was not.

His successors at TTS are working hard to realize that. In a stroke of abject determination, his younger brother Masaaki Furukawa, who is the company’s president, has declared that TTS will build a working prototype by 2018 – not one near the scale of even a miniFUJI, but a tiny primitive version that will produce electricity and prove the concept.

Masaaki Furukawa’s fellow shareholders at TTS include Kazuo Furukawa’s son Kazuro, who is a professor at the Koh Energy Kasokuki higher energy accelerator research group; and chief engineer Moto-yasu Kinoshita.

Kinoshita is also a vice president of the International Thorium Molten Salt Forum and a researcher at the University of Tokyo. We featured him on the Weinberg blog last November from Shanghai, where he was proudly displaying a Chinese language version of Alvin Weinberg’s autobiography, The First Nuclear Era – The Life and Times of a Technological Fixer.

Motoyasu Kinoshita Weinberg Book Halper

The source. Kinoshita displays a Chinese language version of Alvin Weinberg’s autobiography at the       Thorium Energy Conference in Shanghai last November. Weinberg’s MSR design has inspired TTS and other new MSR companies.

I spoke with him  at length this week via Skype, when Kinoshita told me that TTS could begin building commercial FUJIs and miniFUJIs by around 2025.

Obviously, a lot has to happen between now and then, not the least of which will be that TTS has to secure funding.

The company is taking things in stages.

The focus at the moment will require that TTS raise a mere $300,000 – pocket change in the world of nuclear development – to soon test different molten salts. TTS wants to establish which it will use, as it tries to develop a fluid that will not corrode common nickel alloys such as hastelloy and inconel that would form the plumbing in an MSR.

While some competing MSR researchers want to substitute and develop exotic metal replacements, Kinoshita says that TTS is determined to stick with existing materials, an approach he calls “practical and cheaper.”

SEARCHING FOR CHEMISTRY

Instead of material moves, Kinoshita says TTS will apply “chemistry control” to come up with the right recipe of molten salt ingredients that would avoid corroding common alloys.

A typical fluid in MSR designs is a compound known as FLiBe, which is a mixture of lithium fluoride and beryllium fluoride. Kinoshita notes that it is the fluid that Oak Ridge National Laboratory used in the MSR it built in the 1960s under the direction of Weinberg (from whom the Weinberg Foundation, publisher of this blog, takes its name; “FLiBe” is also the namesake of Huntsville, Ala.-based MSR company Flibe Energy, another Oak Ridge inspired group).

In fact, Oak Ridge included beryllium to help avoid corrosion.

But Kinoshita notes that beryllium has its own problems.

“It is not easy to use beryllium – it’s a controlled material because of its toxicity,” he says.

And perhaps more to the point in TTS’ plans – beryllium does not get along well with plutonium, which is one of the “waste” elements that would help form TTS’ mixed thorium fuel.

So TTS is investigating other solutions, such as adding sodium to FLiBe. It is also considering another molten salt called FLiNaK, which is a combination of sodium, potassium and lithium.

Kinoshita is confident that TTS will be able to raise the $300,000, which he thinks could come from anti-nuclear weapon groups who would back the idea of destroying weapons-linked nuclear waste.

THE NEXT TEST

TTS could wrap up its molten salt tests by “this year or next,” Kinoshita says.

It could then focus on a bigger project, would require about $5 million: Testing the behaviour of nuclear waste’s transuranic elements like neptunium, plutonium, americium and curium.

For that, TTS plans to burn simulated-fuel versions of molten salts in a test reactor. It hopes to use the Halden reactor in Norway – the same place where Norway’s Thor Energy will soon begin irradiating a thorium-plutonium mix, with backing from Westinghouse and others.

Other possible test sites would be the Nuclear Research Institute in the Czech Republic, and Japan’s currently halted Japan Materials Testing Reactor.

Kinoshita envisions about five years of the transuranic tests. Then begins the heavy lifting of building the MSR and overcoming technical challenges that all MSR developers face.

FREEZING HOT

Among the hurdles: molten salts in MSRs tend to solidify when temperature drop to around 460 degrees C.  Molten salt reactors are meant to operate at somewhere between 700 degrees C and 900 degrees C. That’s much higher than conventional reactors, and is a reason why MSRs can make more efficient use of fuel (higher temperatures burn more fuel). One of the great attributes of molten salts is that they don’t boil easily – thus they can flow as they need to in an MSR system at high temperatures.

But if things cool too much, they solidify, and pipes can burst. So-called “freezing accidents” would not pose meltdown type threats associated with extreme accidents in conventional reactors, but they would destroy the reactor.

Another challenge: TTS will have to develop chemistry to separate waste from fuel within its reactor. TTS is using a single fluid approach, unlike the dual fluid approach under development at other MSR projects. In a dual fluid MSR, one fluid produces fissile uranium 233 fuel from fertile thorium, and feeds that into a second fluid where reactions take place. TTS’ single fluid technology will have to apply a still unproven technique for separating the fissile uranium 233 from the fertile thorium and from wastes.

On the other hand, companies developing the two fluid approach will have to overcome materials challenges – in a typical MSR design, the silicon carbide that separates the two molten salt fluids can fail (which is why Furukawa decided on the single fluid approach in the first place).

All told, Kinoshita thinks TTS can start building commercial miniFUJIs and FUJIs by around 2025.

As for the 2018 proof of concept model? That will be tough, but not impossible. Scientific geniuses are welcomed to apply at TTS.

Photos: Kinoshita in Norway, Aksel Kroglund Persson/NRK. Kinoshita with Weinberg book, Mark Halper

Comments

  1. Nick says:

    Mark: you write:

    “…MSRs can make more efficient use of fuel (higher temperatures burn more fuel).”

    This is inaccurate and misleading. Heat engines that can tolerate higher temperatures are more efficient because of the laws of thermodynamics. (See Carnot cycle in Wikipedia). Molten salt reactors can be more thermodynamically efficient than pressurized water reactors because there are practical limits to the coolant temperatures in solid-fuel, water cooled reactors. MSRs are less constrained and can operate hotter. Hotter temperature means higher potential Carnot efficiency for the heat engine (steam turbine or gas turbine) which does the useful work.

    Of course, MSRs can also be more efficient in a separate sense, because they can theoretically remove neutron poisons continuously and thus burn up its fuel completely, in contrast to solid-fuel reactors which have no way to remove the generated poisons and must swap out the fuel rods after only a small percentage of the fuel is consumed. This advantage is not directly related to the higher temperatures involved; it comes from using a molten fuel, which lends itself to online processing.

    I’m sure you’re aware of all this, but please try not to lose accuracy when you are trying to be concise.

  2. Alex says:

    Molten salt does not expand when it freezes like water does, it contracts; Therefore a freeze in a pipe would absolutely not cause the pipe to burst unless an especially powerful pump is being used without pressure sensors (so practically never). A blockage would force the reactor to be shut down and clearing the blockage could potentially be a difficult task, but these pipes aren’t like your water pipes in winter.

  3. Ron George says:

    Industry employs heat tracing on pipes and vessels that contain product that will solidify if allowed to cool. The temperatures of the molten salt would require electrical tracing on the piping and heating elements in the vessels, as was envisaged by the guys at Oak Ridge in their (unbuilt) design for a commercial reactor way back in the sixties. They also envisaged that the whole reactor and heat exchangers would be pre-heated before the introduction of the molten salt.

  4. Jagmohan Khanna says:

    I am very passionate to collaborate with Nuclear Scientists in Japan, UK, USA and Canada to undertake research for the commercialization of MSRs (incl Liquid Fluoride Thorium Reactor) Technology.

    I look forward to a positive response.

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