Myths Vs. Facts

When someone writes great words about thorium, there is no need for me to try to “one-up” them.  I just steal what they wrote.  Here is an example that I lifted in toto from Filbe Energy. Enjoy!

There are a number of persistent myths about radiation, nuclear energy, reactors, thorium, and the LFTR itself that are often repeated at all levels of education and experience. This is an attempt to separate myth from fact.

Myth: Thorium is just another idea being pushed by the nuclear industry.

Fact: The predominant “nuclear industry” of today consists of companies like Westinghouse, General Electric, Toshiba, AREVA, Rosatom, Babcock & Wilcox that are pursuing water-cooled reactor designs fueled by solid uranium dioxide. They have expressed very little if any interest in thorium as a nuclear fuel for the simple reason that it is not a good technological fit with their solid-fueled, water-cooled reactors. For them to embrace thorium in a liquid-fueled, high-temperature reactor like LFTR would require a complete “reboot” of their nuclear business strategy thus far, which is heavily dependent on revenues from the sale of fabricated solid nuclear fuel. It is highly unlikely that they will ever have an economic incentive to adopt thorium in a liquid-fueled form, and most of them have evaluated the potential benefits of thorium in a solid-fueled form and found them uncompelling. The notion that thorium fuel is a fad that they are embracing to improve their public relations position has no basis in reality, and is a figment of the imagination of anti-nuclear campaigners who are troubled by the growing interest in the thorium fuel cycle implemented in liquid-fluoride nuclear reactors.

Myth: Thorium as a nuclear fuel has been a failure.

Fact: Almost all efforts to use thorium as a nuclear fuel in the past have been connected with solid-fueled reactors, where as previously mentioned, it does not offer compelling advantages, a fact that we have never contested. The effective use of thorium as a nuclear fuel, by definition, implies a system that employs chemical processing to separate uranium from thorium, and fuel from fission products. Chemical processing of any type is very difficult with solid nuclear fuels, like uranium dioxide fuel or thorium dioxide fuel. It is much simpler with fluid fuels, and simplest of all with liquid fluoride fuels. In liquid fluoride form, the chemical processing needed to realize the potential of thorium as a nuclear fuel is much more straightforward, and thus the benefits of thorium can be realized.

Myth: We know that it will take at least thirty years to build a thorium reactor.

Fact: No one knows how long it will take, but we do have valuable analogies to examine. The Molten-Salt Reactor Experiment (MSRE) went from a new start to criticality in five years, and went on to operate for another five years, in the equivalent of $80M in today’s funding. When Rickover asked the Atomic Energy Commission in the early 1950s how long it would take them to build a reactor for a nuclear submarine, they carefully considered it and told him that one should be ready by the 1980s. The USS Nautilus put to sea in 1954. Drive and determination to achieve a goal, coupled with technological competence, work wonders on the timeline for a new technology development. Given incentive, financial resources, and a responsive regulatory environment, thorium-fueled liquid-fluoride reactors can be designed, demonstrated, and implemented in a reasonable period.

Misrepresentation: Thorium reactors still need uranium or plutonium. This is a proliferation risk.

This is a misrepresentation of how a liquid-fluoride thorium reactor (LFTR) operates. It is true that any reactor, including a LFTR, needs fissile material in order to start up. This is the “initial inventory” by nuclear engineers, and it is necessary for “achieving criticality,” which is what the startup of a nuclear reactor is called. Natural thorium contains no fissile isotopes, so this material must be supplied initially. But it is a misrepresentation to say that LFTRs still need to be supplied with uranium or plutonium after this initial startup. LFTRs generate new fissile fuel from the thorium in their blanket (a region of the reactor that surrounds the active core). In the blanket thorium absorbs neutrons and forms new nuclear fuel, uranium-233, which is chemically extracted and added to the fuel salt of the LFTR. So after being provided with the initial fissile material to start the reactor, it doesn’t need anymore. It uses the neutrons of the fission reaction to continue to make the fuel it needs. Furthermore, if enriched uranium or plutonium were to be used to start LFTRs, this would not constitute a “proliferation risk”. Using this material to start a LFTR is not going to help countries that don’t have nuclear weapons to obtain them. Rather, it would work against that risk by permanently destroying this material (through fission) and replacing it with a material (uranium-233) that has strong intrinsic barriers against diversion for use in nuclear weapons.

Misrepresentation: Using thorium would require a resumption of reprocessing in the United States.

This misrepresentation requires some additional background explanation. Early in the nuclear era, it was assumed that the spent nuclear fuel produced from solid-uranium-fueled reactors (which also contained plutonium) would be chemically processed to separate the uranium and plutonium from the fission products and from one another. Then the uranium and plutonium would be refabricated into new solid fuel pellets and used again in uranium-fueled reactors. There was particularly strong interest that the uranium/plutonium fuel would be used for sodium-cooled fast breeder reactors. France built a huge chemical processing facility for nuclear fuel at La Hague for this purpose. There was a fear that the same chemical processing technology that would be used to handle civilian spent nuclear fuel would be exported, along with civilian nuclear power plants, to developing countries around the world that did not already have either a civilian nuclear power program or a nuclear weapons program. The fearful scenario continued with the expectation that the possession of the technology to chemically separate plutonium from uranium would prove so tempting to those non-weapons countries that they would build special plutonium-producing “production” reactors, just as the US, USSR, UK, France, and China had done, in order to produce plutonium for nuclear weapons, and then employ the chemical processing technology to extract that plutonium and use it to fabricate weapons.

This never happened. Any country that wanted to develop nuclear weapons did so prior to obtaining civilian nuclear power or chemical processing technology. Other countries like Germany and Japan developed conventional chemical processing technology for nuclear fuel but never built “production reactors” or fabricated nuclear weapons. Furthermore, conventional nuclear chemical processing has nothing to do with the liquid-fluoride thorium reactor (LFTR) technology we advocate since the chemical processing in a LFTR is based on fluoride chemistry (totally different from conventional chemical processing technology) and on the separation of uranium from thorium, not plutonium from uranium. The chemical processing technology proposed for a LFTR would be ineffective if someone attempted to use it to separate plutonium from uranium, and furthermore the LFTR is designed to make as little plutonium as possible. If plutonium is used to start a LFTR, it is consumed in the first few months as the reactor establishes its fuel cycle, again, based on thorium and uranium-233. The chemical processing system proposed for use in the LFTR is entirely contained in the reactor facility, and operates at high temperatures and under high radiation fields. It is essentially impossible to repurpose this system once it has operated, and it simply isn’t designed to produce any materials suitable for weapons.

Those who perpetuate this misrepresentation play on public ignorance of different chemical processing techniques to cause people to believe that conventional, aqueous reprocessing techniques (often called “PUREX”) are just the same as those that would be used in the LFTR. They’re not. In fact, they’re absolutely nothing like one another.

Myth: There’s no point to developing thorium reactors because it will still produce radiation.

Fact: Yes, the fission of uranium-233 from thorium will still produce fission products that are highly radioactive, and these will have to be carefully isolated until they decay away. But to reject fission because of the production of radioactive materials is to miss a tremendous opportunity to help mankind. Many desirable products of thorium reactors come about precisely because the fission products are radioactive. The beneficial use of medical radioisotopes relies on the fact that these products are radioactive, which allows them to be used for imaging and treatment in the body. Fission reactions are the only practical ways for many of these medical radioisotopes to be generated in sufficient quantities and at affordable prices. Furthermore, nearly all fission products have short half-lives, which means that they rapidly decay to a stable, non-radioactive state. Only a handful of fission products, including strontium-90, cesium-237, and samarium-151, have half-lives that require isolation beyond a century.

Myth: Molten salt will explode on contact with air and water.

Fact: Anti-nuclear campaigners who propagate this myth are confusing chemically-stable fluoride salts with chemically-reactive liquid metals like sodium that have been proposed as reactor coolants in other types of reactors. Fluoride salts do not explode or react with air and water because of their tremendous chemical stability. Furthermore, they chemically trap important fission products like strontium and cesium as very stable fluorides in their fuel form. Finally, to be clear, liquid metallic sodium (not used in liquid fluoride reactors) is very reactive with air and water; sodium chloride (table salt, also not used in liquid fluoride reactors) is not reactive; sodium fluoride (sometimes used in liquid fluoride reactors) is not reactive and is even more chemically stable than sodium chloride.

Myth: All radiation is dangerous at any dose level.

Fact: We are continuously surrounded by radiation, nearly all of which comes from natural sources. Our bodies themselves are naturally radioactive due to the presence of carbon-14 and potassium-40. All lifeforms have radiation repair mechanisms and indeed are always repairing radiation damage to their DNA, a great deal of which comes from being exposed to the Sun. Small doses of radiation are not dangerous because they do not overwhelm the body’s radiation repair mechanisms, and most natural and manmade doses are very small.

Myth: Radiation is a silent threat that is difficult to detect.

Fact: While we do not have natural senses that detect ionizing radiation, radiation in utterly miniscule quantities is easy to detect and verify with modern instruments, and the various signatures will determine whether it is naturally-occurring or manmade. The intensity of the radiation will allow trained personnel to evaluate the potential risk.

Myth: All radioactive material is dangerous, and a long half life means it is really dangerous.

Fact: The longer the half-life, the less radioactive and less dangerous a substance is. Some radioactive materials with long half-lives, such as plutonium-239, are hazardous only in certain conditions such as inhalation because of their specific type of radioactive decay (alpha emission). Fission products—the results of the fission reaction—do not decay by alpha emission but rather by beta and gamma emission. This still presents a hazard but one of a different nature, and one that is well-understood.

Myth: radioactivity lasts forever.

Fact: Radioactivity means the material is decaying away and the most radioactive substances are those that are going away the most quickly.

Myth: Nuclear energy equals nuclear weapons.

Fact: Nuclear reactors that generate power and nuclear weapons are totally different things. Every country that has developed nuclear weapons has done so because they set out to do so. They used the same techniques that the United States did during the Manhattan Project of World War 2, namely the enrichment of natural uranium and the production of plutonium in dedicated nuclear reactors meant only for this purpose. No country has taken electricity-generated nuclear reactor technology from another country and perverted it into a means to produce nuclear weapons. Furthermore, the inherent resistance of thorium and its byproducts to use in nuclear weapons were the central reason why it was rejected for use in nuclear weapons during the Manhattan Project and why it has lagged in development ever since.

Myth: The world will never change and accept energy from thorium.

Fact: The world is always changing. We have to decide whether to make the changes needed to embrace this natural, sustainable, reliable and economical energy source.

bwr

Quit Living in the Cellar

I want my fellow Utahns and the rest of the world to stop living in the cellar and move into the penthouse. Please take a look at the graph below and I will explain. (Graph was adapted from Balsara and Newman.)

Specific Energy Density GraphAt the left side of the graph is the cellar where we are currently living – fossil fuels and lots of Tesla talk about batteries. The graph is on a log-log scale; both axes are logarithmic.  That means that each division (line) going from left to right and from top to bottom is 10 times more that the previous one.

Also, the graph plots theoretical specific energy density versus what is actually delivered in practical, every day use. Thus, all of the things shown on the graph are to the left of the dotted line, which represents the case where the practical is equal to the theoretical, which never happens in reality.

Let’s consider gasoline, which I like and have no intention of giving up. It has a practical energy density of 3,870 Watt-hours per kilogram, which is considerably more than lithium-ion batteries at 250 Watt-hours per kilogram. This is the reason that 12 gallons of gasoline in a four-door car will take you about 350-400 miles in air conditioned comfort, while an electric car may take you 100 miles or far less if you use the AC.

Next, take a moment and follow the dotted line to the right. You will see two data points at the top right; plutonium  decay (Pu-238), and nuclear fission.  These are points that I added to the graph, since Balsara and Newman never mention nuclear energy in their paper. (Why?)

Pu-238 decay powers spacecraft that have gone to the outer planets and beyond, where solar panels are useless, because they are so far from the sun.

(This technology has been used in spacecraft such as Voyager 1 and 2, Cassini–Huygens and New Horizons, and in other devices, such as the Mars Science Laboratory, for long-term nuclear power generation.)

The photo below shows a pellet of plutonium 238 that glows red hot due to the self-heat it generates as it radioactively decays. (Don’t worry, the alpha particles that are characteristic of its decay can be stopped by a sheet of paper, but you might want to use something that doesn’t burn. You can stand next to thermoelectric generators made for satellites with this wonderful element, without risk.)

plutonium_238_pelletNuclear fission, the point farthest to the right on the graph, with a mind-boggling theoretical specific energy density of 24,500,000,000 Watt-hours per kilogram, is the penthouse I am inviting you all to enjoy.

The specific energy density of nuclear fission is 2.7 million times more dense than gasoline and 63.6 million times more dense than lithium ion batteries. This would also be a good point to mention that batteries do not produce energy of themselves. They have to be charged by electricity produced by oil, coal, solar, wind, hydro, or nuclear.

Because of the incredible amount of energy locked in the nuclei of certain elements (thorium, uranium, and plutonium) as shown by the graph, very little material is needed to provide vast amounts of energy for all of us. As I have mentioned before, there is enough of those elements to provide all of humanity with abundant, safe, clean energy.

I compare that energy abundance to leaving the cellar and moving to the penthouse!