The Weinberg Foundation

The illusions of molten salt reactors, science and politics

May 10th, 2013

Posted by Stephen Boyd

Written by guest blogger Dr. Stephen Boyd

Los Molten Salt? Los Alamos National Laboratories, the anchor of the Manhattan Project in the 1940s, to this day has plenty of nuclear expertise. Some researchers would like to see it add molten salt development.

Stephen Boyd PhD spent a week recently touring New Mexico, where he visited the famed Los Alamos laboratory and spoke at a space energy conference in nearby Albuquerque. He’s still buzzing with observations on unwise reactor designs, heroic scientists, flimsy U.S. energy policy, the enormous potential of molten salt and on how things aren’t always as they appear. He treated us to this trip report…

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Appearances are quite often deceiving. My recent participation in a leading space technologies conference in Albuquerque, and my subsequent meetings with fellow researchers at the nearby Los Alamos National Laboratories affirmed this observation over and over again. Let me explain…

My colleagues and I have written a paper questioning the use of silicon carbide as a material in fluoride molten salt reactors (MSRs) and in other high temperature reactors. Many space experts have a keen interest in MSRs, which could potentially power spacecraft and provide energy on “off-earth” places such as Mars and the Moon. I was thus pleased when our paper earned me an invitation to speak at the recent Nuclear and Emerging Technologies for Space (NETS) conference, which tackled the challenges of energy in space head on. The paper is up for peer review in the NETS conference publication.

A quick review for those of you new to the subject: It’s not just the space community that is interested in MSRs. Chemists, physicists and engineers in the U.S. and around the globe have a rekindled interest in them as a safe, efficient, environmentally friendly, CO2-free power source. This type of nuclear reactor, studied extensively (and nearly exclusively) in the U.S. from the 1950s-1970s, differs dramatically from conventional, solid-fuel nuclear reactors. In a molten salt reactor the nuclear fuel is the salt; the salt is molten (due to the high heat) and used as the working fluid, so the fuel acts its own coolant. The fluid design provides safety and operational advantages of conventional solid fuel reactors.

China and India are conducting considerable research and development into liquid-fueled MSRs. By comparison, the U.S. Department of Energy is only timidly pursuing the concept. It has helped to fund a handful of projects at universities, and these projects are not exploring full-on molten-fueled reactors. Rather, they are examining molten salts as coolants, while keeping the fuel in a solid form.

BEWARE SILICON CARBIDE

Across the world, government and private initiatives are considering using silicon carbide (SiC) as a structural material for pipes that contain the molten, circulating salts. Others are proposing it as cladding to coat specialized solid-fuel pellets commonly referred to as “pebbles” in proposed “pebble bed reactors” that would use solid pebble-shaped fuel cooled by molten salt.

Our contention is that SiC is a poor material. In our paper we cite experimental evidence collected over the decades that, we assert, demonstrate this point. Normally, SiC is an excellent refractory material (a material that retains its structural strength even at high temperatures).

At issue here is the combination of high heat and aggressive molten fluorinating salts. SiC, and silicon-based compounds in general do not perform well at all even at room temperature with fluoride-based compounds. They tend to dissolve, much like salt in water. At a macroscopic level, some reports have demonstrated no effect. But remember – appearances are sometimes very deceiving. We assert and cite evidence that if you look at the microscopic level, you will see substantive dissolution of the SiC, reflected in both the disappearance of the SiC, as well as the appearance silicon-based residues in post-facto studies.

Anyone who heard me speak in Albuquerque will hopefully now understand the considerable risks of SiC in an MSR, and will hopefully care enough to act on what may, indeed, prove to be a major design flaw of an all-important reactor.

Certainly, there were plenty of impassioned people gathered at NETS who could make a difference in pushing forward a clean and sustainable energy future with innovative MSRs playing a big role.

EXCITING STIFFS

But to the casual onlooker, the fervent nature of these individuals might not have been obvious. These avid believers were, after all scientists. For any of you who have attended such a conference, the scene was typical: attendees milling about with staid tones and conversations.

There’s that deception again. I had a chance to sit in on many of the talks, where one could not help but conclude: Scientists must be some of the most passionate people on the planet (myself included). We investigate the fundamentals of matter and energy and we use the Three Laws of Thermodynamics, Quantum Mechanics and applications thereof to do so. We explored NETS’ bold theme of conceiving novel forms of energy production for extended human off-world occupation.

Mile high meeting of the minds. Greetings from Albuquerque, 5,312 feet above sea level, where scientists from across disciplines gathered with great verve to sort out the future of energy in space.

Talk after talk thrust robust skill sets to the fore: intense chemistry, nuclear physics, engineering and materials science that could deal with the extremes of space, lunar or Martian environments. We debated how to handle unfamiliar pressures, temperatures, and the prolonged absence of maintenance and how to deploy technologies with as few moving parts as possible and build clever nuclear batteries and propulsion.

My three-day stop at NETS at the end of February was just the first half of a trip that was populated all along the way by ardent big thinkers.

I remain grateful and honored to have been invited by an excellent staff scientist at the nearby Los Alamos National Laboratories (LANL) to give a talk and meet with scientists there. This was truly a dream come true. I was humbled to be there at LANL, where I was standing on the shoulders of true giants: Feynman, Born, Dirac, Oppenheimer, Teller, Seaborg – to name just a few.

My host (a density-functional theorist by training) was the consummate docent. He arranged meetings for me with a slew of world-class researchers in my fields of interest: materials science, nuclear power-plant design, metallurgy, crystallography, synthetic chemistry.

You see, several goals motivate me. As an entrepreneur, I remain keen on building an energy company focused on making molten salt nuclear reactors a reality – be they terrestrial or off-world. I would prefer using thorium as my fuel, However, I am fine with an “interim” fuel such as low-enriched uranium-235, which is available on the world market and well-known as far as its nuclear chemistry and physics profiles are concerned.

THE PRIVATE PUBLIC CHALLENGE

I have free-market concepts in mind, but as a researcher, some experiments with “hot” materials like uranium-235 are simply not feasible in my start-up laboratory – it costs millions of dollars for a combination of reasons including licensing and waste disposal. I was hopeful that LANL – a U.S. Department of Energy lab – might be able to play a role. They have world-class scientists who specialize in a range of materials and coatings that could be safely used within the brutal environment of a molten salt system. Unfortunately, in my discussions with representative from the LANL Technology Transfer Division, I was told that no federal funding at all is available.

I was frustrated, but I quickly realized that I wasn’t the only one.

On my trip to New Mexico, scientists’ consternation with the illusion of Washington’s energy commitment was palpable. On more than a few instances they voiced their frustration with funding limitations, inconsistent rhetoric and a lack of vision on the part of the U.S. Department of Energy and Congress.

Several scientists were stunned at the comparative advances many nations are making in molten-salt reactor research and development. Canada, Russia, China, the Czech Republic, Australia and India are conclusively ahead of the U.S. and pull further ahead with every Congressional slash, every DoE diversion.

So, what have I gleaned by my interactions with LANL and NETS scientists? Where are we, as a nation, as Americans, relative to the world? Scientists possess some of the greatest ideas, creativity and sheer gumption with respect to emerging technologies and cutting-edge innovation, as well as what they believe should be studied: sexy science and math problems which simply are not being funded, and for vague and nebulous reasons. Those seemingly staid individuals have the passion, really to save the planet.

Ironically, however, the politicians in Washington who are given to more flamboyance, and to loud “rescue the planet” proclamations, are not as interested. If they were, they would be paying more attention to possibilities of nuclear research and development such as molten salt reactors. That is the flip side of the deceiving appearance: just like those who seem uninspired are full of zeal, those in Washington who appear rhetorically impassioned are actually less interested.

CAUTIOUS CONFIDENCE

I remain optimistic – bolstered by the enthusiasm of the world-class researchers who welcomed me, my ideas, and my chemistry. I remain cautiously confident that the right mix of American entrepreneurial spirit, investment capital, and collaboration with LANL and other government laboratories and maybe even international efforts will foment the momentum so desperately needed to bring humanity’s energy needs (both on this planet and off-world) into the 21st Century and beyond. I am truly hoping that appearances really are deceiving, as many chemists and physicists view Washington with such abject disappointment.

I truly hope we are wrong about Washington and that the ostensible apathy and lack of direction are, in fact, false, and that the U.S. (with its 22 national laboratories leading the way), again demonstrates the practices that once placed us at the forefront of the world for cutting-edge research.

And, of course, I hope my optimism is not deceiving me.

Photos: Los Alamos National Laboratory from LANL. Albuquerque from itsatrip.org

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Dr. Stephen Boyd is CEO of Havelide Systems Inc. and CTO of Aufbau Laboratories, LLC, both energy IP companies in Blue Point, Long Island, New York. He is also a post-doctoral fellow in the Physics/Astronomy Department of Hunter College in New York City, focusing on chemical energy retrieval and storage. Dr. Body is developing technologies to advance molten salt reactors. He has a PhD in solid state chemistry/chemical physics and degrees in international finance and political science. You can reach him at stephen.boyd@havelide.com or aufbaulabs@gmail.com.

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Categories: Economics, Efficiency, Safety

The nearness of fusion: The materials and coolant challenges facing one fusion company mirror fission

April 30th, 2013

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Posted by Mark Halper

Fancy bow tie. Helion’s Fusion Engine fires plasmoids of deuterium and tritium at each other from either end. They collide and fuse in the middle, giving off direct electricity as well as heat captured by a coolant that could be FLiBe.

The paradox of fusion energy is that it is always 40 years away, and has been for some 60 years.

So scoff the fusion skeptics. And if you look at the projected timelines of the large intergovernmental fusion projects like ITER in France and NIF in California, you could easily join the ranks of those not holding their breath.

But as I’ve written here before, there are a number of smaller and privately-backed fusion initiatives that could solve the fusion riddle long before the ITERs or NIFs do.

One of those companies is Helion Energy, a Redmond, Washington-based company that claims it will build a 50-MWe pilot of its “Fusion Engine” by 2019 after which licensees will begin building commercial models by 2022. That’s hardly the 40-year odyssey we’ve long heard about.

Helion will obviously have to overcome many challenges in order to take the express lane to fusion land. I won’t write about all of them in this post.

But what strikes me as particularly relevant to Weinberg readers is how Helion (and the fusion community in general) is facing materials challenges and decisions that are similar to those confronting developers of alternative fission technologies like fast reactors and molten salt reactors (MSRs).

For example, Helion is contemplating the use of FLiBe – the molten salt that’s part of MSR designs – as a coolant and an electrical insulator. It’s also examining the abilities of different metals to withstand ferocious neutron bombardment – just the sort of thing that many fission researchers are also investigating as they try to move away from conventional fission reactors and to higher temperature and other alternatives.

FUSION’S PROMISE

Before I dive in to Helion, and in case anyone needs a refresher: Fusion joins atoms together rather than splits them apart as fission does. Many experts regard its as the Holy Grail of energy sources, noting among reasons that fusion does not leave long-lived high-level waste; that it requires comparatively little fuel and its fuel is to a large extent easy to obtain and plentiful; and that it cannot meltdown (even if it does require temperatures of over 100 million degrees C) and leak harmful radioactivity. (It also creates helium, a substance with many uses but one that is in increasingly short supply).

“Fusion has the potential to provide nearly limitless, clean energy for both baseload and on-demand power,” notes David Kirtley, Helion’s interim CEO, who I spoke with via Skype recently. “Fusion fuels are inexpensive, sustainable and can be supplied with minimal environmental footprint.

Don’t try this at home. Helion has built and tested an experimental version of the engine, without the coolant and heat exchanger.

Helion’s small “Fusion Engine” uses principles of magnetism to generate heat that induces istopes of hydrogen to fuse. But it bears little visual resemblance to the giant 20-story “tokamak” that ITER is building in Cadarahce, France using different techniques of magnetism.

The Fusion Engine is a 28-meter long, 3-meter high bow tie-shaped device that at both ends converts gases of deuterium and tritium (isotopes of hydrogen) into plasmoids - plasma contained by a magnetic field through a process called FRC (field-reversed configuration). It magnetically accelerates the plasmoids down long tapered tubes until they collide and compress in a central chamber wrapped by a magnetic coil that induces them to combine into helium atoms. The process also releases neutrons.

The Fusion Engine provides energy in two ways. Like in a fission reactor, the energy of the scattered neutrons gives off heat that ultimately drives a turbine. Helion is also developing a technique that directly converts energy to electricity. The direct conversion will provide about 70 percent of the outgoing electricity according to Kirtley.

IN AND OUT

The overarching problem that Helion, ITER, NIF, and others are working to solve is that the amount of energy it takes to coax sustainable fusion reactions is greater than what can be harnessed from the reactions.

When you consider that temperatures inside many fusion designs hit 150 million degrees C, albeit briefly, then you can start to appreciate the amount of energy required to get things cooking. In Helion’s case, it is powering capacitors that convert the deuterium and tritium gas into plasmoids. It is also powering electromagnets that surround the narrowing cylinders through which the plasmoids shoot. The pulsing magnets induce the plasmoid to accelerate.

A fusion chamber also requires durable materials – doubly so since neutrons bombard the inside walls, severely testing their durability (except for in a process called “aneutronic fusion,” but more on that another time). Therein lies one of the main crossover points between fission and fusion development. Both are looking for materials that can handle high energy neutron bombardment and high temperatures. Although fusion has a kinder brand image than does fission, the fact is that it sets neutrons racing about just as fission does (again, aneutronic fusion does not do this).

For Helion, this means finding the right material to line the inside of the compression chamber where the plasmoids collide and release neutrons.

“This wall is exposed to high levels of radiation and high thermal load,” notes Kirtley. Helion is considering alloys including tungsten, beryllia and molybdenum. These materials will be familiar to engineers and scientists working on high temperature fission reactors. As Kirtley notes, “the tungsten alloy claddings in high-temperature reactors absolutely share material crossover.” Helion’s collaborators on so-called “first wall” development include the U.S. Department of Defense and the University of Washington, he says.

A man of two fusions. Helion co-founder John Slough and his company MSNW are designing a separate fusion reactor, called the Fusion Driven Rocket, meant for spacecraft propulsion.

As important as durability is, Helion has another ace up its sleeve. It has devised a technique that allows for “rapid replacement” of the wall, a breakthrough that Kirtley describes as “one of the key advantages” of the Fusion Engine. “We believe it is key to the engineering design of an economically feasible fusion energy system,” he says.

In Helion’s Fusion Engine, a coolant material will form a blanket that absorbs the neutrons and their heat after the neutrons escape through the wall. As is the case with some fission research companies, Helion is not yet sure what coolant it will use, although its preference is FLiBe – a molten salt of lithium fluoride and beryllium fluoride. The MSR reactor community will recognize FLiBe as one of the fluids that can serve as both a coolant blanket and a fuel carrier in an MSR. It is the substance that lends its name to Flibe Energy, the Hunstville, Ala. company that is developing a two-fluid FLiBe-based MSR.

Helion is also considering using lithium as the blanket coolant. Lithium is a common choice in fusion designs because it reacts with the neutrons to make tritium. Of the two hydrogen istopes commonly used in fusion – deuterium and tritium – tritium is the more difficult to obtain (deuterium is found commonly in seawater), so a process that replenishes tritium via interaction with lithium is a popular design among fusion engineers. Kirtley claims that Helion’s fusion process requires less tritium than do other fusion technologies and that the Fusion Engine makes some of its required tritium by fusing deuterium atoms in the collision.

“Our reactor design removes the majority of the complex tritium producing blanket,” says Kirtley.

Thus Helion has less need to breed tritium from lithium and it is therefore looking seriously at FLiBe, which is a more effective, less expensive and less problematic coolant than lithium, he notes.

FLiBe’S FUSION HISTORY

The idea of using FLiBe as a fusion coolant is not new. The U.S. Department of Energy’s Idaho National Laboratory has investigated it in partnership with Lockheed Martin, the aerospace stalwart that is also developing a fusion reactor. Likewise, Ralph Moir, the physicist known for his interest in hybrid fission/fusion reactors , published a paper on a fusion FLiBe coolant over 20 years ago at Lawrence Livermore National Laboratory in which he notes that FLiBe avoids the fire hazards of lithium as a fusion coolant. MIT and Argonne National Laboratory published separate papers on FLiBe and lithium’s usefulness in fusion reactors in the 1970s.

FLiBe might serve a second purpose on Helion’s Fusion Engine as well. Kirtley says the company wants to use it to provide electrical insulation to the electromagnets. By using FLiBe for that function as well as for the coolant blanket, Helion would simplify its materials needs and lower its costs, he notes.

Helion’s design comes from company co-founder John Slough, who is also a research associate professor at the University of Washington and who runs Redmond-based space propulsion firm MSNW LLC.

Slough is a fusion enthusiast, to say the least. He is designing a separate fusion reactor intended as a propulsion device that in principle could send manned spacecraft to Mars in 30 days. That project known as the Fusion Driven Rocket, has funding from the U.S. National Aeronautics and Space Administration.

The more earthly Fusion Engine has received about $7 million in funds from DOE, the Department of Defense and NASA. The company hopes to raise another $2 million by next year, $35 million in 2015-17, and $200 million for its pilot plant stage.

It will compete for development funds with other fusion initiatives, such as those at General Fusion, Lockheed Martin and the “aneutronic fusion” projects at Lawrenceville Plasma Physics and Tri-Alpha Energy. It will also compete against fission development. But given some of the material similarities with fission, it might also find itself in collaboration with some of those efforts.

Images provided by Helion. Photo of John Slough from Redmond Reporter via Helion.

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Categories: Efficiency, Safety, Waste

Liquid fission: The best thing since sliced bread?

April 22nd, 2013

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Posted by John Laurie

Written by guest blogger John Laurie

What do the two men above have in common?

Give up?

Well, they both made great contributions to humanity by proposing a change to the established order in which things are done.

The man on the left was the first to say “Hey, why don’t we cut the bread BEFORE we sell it?”

The man on the right was the first to say “Hey, why don’t we have the meltdown BEFORE we put the fuel in the nuclear reactor?”

In 1927 Otto Frederick Rohwedder successfully designed a machine that not only sliced the bread but wrapped it. Missouri’s Chillicothe Baking Company installed his first machine, and the first loaf of sliced bread was sold commercially on July 7, 1928. Sales of the machine to other bakeries increased and sliced bread soon became available across the USA.

Alvin Weinberg and his team at the Oak Ridge National Laboratory (ORNL) pioneered liquid fission, building and operating the world’s first nuclear reactors to use a liquid fuel composed of molten fluoride salts.

The Molten Salt Reactor Experiment ran successfully at ORNL from 1965 to 1969. Raw materials were prepared using a meltdown furnace, then allowed to cool before being shipped to the reactor site for re-melting and transfer into the drain tanks of the reactor. The word “meltdown”, which has become synonymous with major accidents in solid fuelled reactors, describes a completely normal and safe process in liquid fission.

The ORNL team proved that this technology could be cheaper, safer, more efficient and generate far less waste than solid fuelled reactors, only to see their funding cancelled and the team disbanded, mainly for political reasons.

But advocates of liquid fission should take heart from the story of sliced bread. Rohwedder originally began working on the bread-slicing machine concept in the 1910s. Unfortunately a fire in 1917 destroyed the factory that was to produce the invention, and the original blueprints. It took him 10 years to recreate his invention.

It’s been over 40 years since Alvin Weinberg built his liquid fission machine. Now a new crop of researchers are picking up where he left off. It’s time for his idea to flow.

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John Laurie is a bilingual design engineer who found out about liquid fission last year. He has a web site called Energie du Thorium which brings information and news on thorium and molten salt reactors to a French speaking audience.

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The Weinberg Foundation is a UK-based not-for-profit organisation dedicated to advancing the research, development and deployment of safe, clean and affordable nuclear energy technologies to combat climate change and underpin sustainable development for the world.