What is spent fuel anyway?

December 27th, 2007
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There’s a lot of talk about “nuclear waste” and what should be done with it. There are different categories of radioactive waste which include everything from very low level material like contaminated lab coats and beakers from radiological tracers all the way up to highly concentrated high-energy radiation sources. Generally the majority of such waste is not especially difficult to deal with, as much of it is not actually very radioactive at all. But there is one kind of “waste” which has been the subject of a lot of debate recently, especially in the United States.

That material is “spent fuel,” the uranium fuel rods from reactors which have been used for power generation and are no longer suitable for sustaining fission in typical reactors. This material is currently being stored on site by nuclear power plants, as it has since the 1970′s. Much of it is in “spent fuel pools” where it is submerged in water for shielding and cooling. Other, generally older, spent fuel is in “dry storage” in concrete or metal casks also primarily located on site at nuclear reactor locations. In the US alone there are hundreds of thousands of metric tons of spent fuel in storage and nuclear plants and elsewhere. Even more is located at other sites worldwide.

The current plan in the US is to move the spent fuel by road and rail to the Yucca Mountain federal repository site in Nevada. There, the spent fuel and other “waste” materials would be placed in tunnels, located deep within the rock of the mountain. Geological studies have been done in the area and the Department of Energy is confident that the materials could be safely entombed in the mountain for hundreds of thousands of years. The repository was supposed to begin accepting shipments in 1998, but due to opposition and delays it will probably not be fully operational for at least another decade.

Needless to say, this has been an issue which has garnered the attention of the eco-stupid movement. It has also been the subject of criticism on the pro-nuclear side. Many other countries manage their nuclear waste through reprocessing programs. In the US, all reprocessing activities ended by the Carter Administration. It was claimed that reprocessing of nuclear fuel could lead to proliferation of nuclear weapons. Apparently, Mr. Carter was not aware that the US already had thousands of tons of weapons-grade material stockpiles and tens of thousands of nuclear warheads already assembled, and therefore the recovery of added plutonium would not really change much, especially considering that reactor grade plutonium is not suitable for use in weapons.

Despite the fact that many seem to have opinions about what should be done with spent fuel and the fact that spent fuel “waste” is one of the biggest issues in the anti-nuclear movement, few seem to even know what the material is made of. So here’s the breakdown of what we’re dealing with. The amounts will vary depending on the type of reactor, but these numbers represent a typical lightwater power reactor, like those used in the US and around the world for electricity production:

Uranium: ~94-96%

The fuel that goes into a reactor starts off as uranium and when it comes out, it’s mostly still uranium. Natural uranium consists of about .7% uranium-235, which the remainder being almost entirely uranium-238. Since uranium-235 is the easily fissionable isotope, it’s concentration is increased through “enrichment” for use in reactors. When the fuel goes into a commercial nuclear reactor it is usually around 3% uranium-235. After being used, it contains about .9%-1.2% uranium-235, which has not been fissioned by the reactor. This is generally higher than natural uranium, making the material an even richer source of U-235 than natural uranium minerals.

Other isotopes of uranium may be present in smaller quantities. These include uranium-236, which forms when a U-235 atom captures a neutron but does not fission. U-236 may be in concentrations of about .4% or so. It’s not really very useful, as it does not fission easily and has a relatively low neutron cross section. With a half-life of a few million years, it’s a bit more radioactive than most other isotopes, but not radioactive enough to be considered much of a danger. If the uranium is recycled, the U-236 remains in the mix. It may be fissioned in a fast neutron reactor but otherwise is basically neither a resource nor a major problem.

Plutonium: ~1%-2%

Plutonium is formed when uranium-238 captures a neutron and rapidly decays to neptunium-239 and then plutonium-239. All reactors produce some plutonium, although breeder reactor are designed especially to do so. Plutonium-239 has a half-life of 24,000 years and is a strong alpha emitter. Comparatively speaking, plutonium is not nearly as dangerous as many other radioisotopes, including some natural ones like radium-226. However, it can be quite toxic if it is ingested or inhaled and the longer half-life means that disposing of plutonium presents concerns about the long-term stability of a site.

But there’s another way to get rid of plutonium which can turn a waste product into an asset. Plutonium is fissionable and thus can be used as reactor fuel. It can be burned in a standard lightwater reactor in the form of MOX (mixed oxide) fuel or it can be burned with even higher effeciency in a fast neutron reactor. This not only reduces material to be disposed of but increases the effeciency of the fuel cycle, possibly by up to 200 times, if all the avaliable energy is extracted by plutonium breeding and recovery.

One thing the plutonium from a standard power reactor is NOT suitable for, however is weaponry. This is because it contains too high a ratio of plutonium-240 to plutonium-239. Although plutonoum-240 is not a problem for reactors, it is a neutron emitter, which in a bomb, would cause the reaction to start too soon and the weapon to “fizzle” and fail. Weapons grade plutonium must contain at least 80% plutonium-239, but most reactor grade plutonium contains less than 70% plutonium-239. It is theoretically possible to build a weapon from reactor grade plutonium and the possibility was demonstrated by nuclear experiments in the 1970′s, however doing so requires a highly efficient weapon design, is extremely unreliable and suffers from reduced yield. In general, such material is very difficult to weaponize and would probably not be worth the effort even when compared to construction of a purpose-built weapons grade breeder reactor.

Minor Actinides: <1%

Minor Actinides are heavy elements other than uranium and plutonium which are the result of neutron capture, usually by plutonium which does not fission. They include neptunium, americium and curium. The amount present in spent fuel will vary but is higher in reactors which have high levels of plutonium. They generally have halflives of a few decades or more and are therefore somewhat hazardous, but only when highly concentrated. They are able to fission and can be used in standard thermal reactors, but they are more easily and efficiently fissioned in fast neutron reactors. In some cases, these isotopes are also useful in a concentrated form for use as a neutron source or for industrial radiation sources. Americium-241 is commonly used in industry as well as in smoke detectors. Californium isotopes such as Ca-252 are commonly used as neutron sources.

Fission Byproducts: About 3%

These are the materials which result from the actual fission of heavy element atoms. Each time a uranium or plutonium atom splits, it results in two new atoms. The new materials vary in type but tend to have an atomic mass around 80 to 100 or 130 to 150. A few of these are actually stable but most are radioactive and have varying half-lives. Fission products can be loosely categorized into three major groups:

Short-lived: The vast majority of fission products have relatively short half-lives of a year or less. These isotopes are highly radioactive and contribute to the vast majority of the radioactivity in freshly used fuel. They are quite hazardous and can can be dangerous to be exposed to even for a short period of time without shielding. However, they are not a disposal problem because of the short half life of the materials. Since the shortest lived isotopes are also the most radioactive, the spent fuel will rapidly loose most of its radioactivity and be less than 1% as radioactive after one year as it was to begin with. Simply allowing the spent fuel to decay for a period of a few years or more will eliminate these highly radioactive materials.

Medium-lived: These are the fissio n byproducts which have a half life of more than a year or two but less than centuries. These makeup about 10%-20% of the total fission byproduct yield. These can be something of a hazard, especially when highly concentrated. However, they still are long-lived enough that they require disposal of some type. Generally about 300 years is all that is needed to assure that they have been nearly eliminated from any waste material and the material is no longer any more hazardous than natural uranium ore. From a geological standpoint this is a very short period and it is not difficult to assure that a geological formation will remain stable for such periods of time.

These materials can also be destroyed by photoneutron transmutation or by bombardment with fast neutrons. However, the two isotopes which account for most of the medium-lived byproducts, strontium-90 and cesium-137, both have relatively small neutron capture cross-sections and strong binding energies. Because of this it is not generally considered to be worthwhile to transmutate these materials. When diluted and embeded into chemically inert materials, they are considered safe and will be similar to natural radioactive minerals in a relatively short period of time.

Long-Lived: These makeup about 20% of the total fission product yield and are the isotopes with half-lives of thousands or millions of years. They include technetium-99, iodine-129 and cesium-135. Because of the long half-lives they are not nearly as hazardous as other radioactive materials, but they will continue to be radioactive for a long period of time. It is important to note that they are on par with numerous natural radioactive materials such as potassium-40, which is quite common in any potassium-baring compound.

Most of these materials do have a suffecient neutron cross-section that they can be transmutation into shorter-lived isotopes by fast spectrum reactors. Therefore, irradiation of fuel by a fast spectrum reactor will have the net effect of reducing these materials, possibly by more than half. However, even without such treatment, disposal of such materials in chemically stable mediums does not present a hazard beyond that of natural radioactive minerals. Compared to uranium deposits, which contain radium-226 and polonium-210, such material is quite low in overall radiotoxicity, even in the short term. When combined with medium-lived fission products the immediate radiotoxicity is only marginally higher.

Disposal of such materials: In order to dispose of fission products which are long or medium lived, a few options exist. As mentioned, it is possible to destroy these materials and in some cases get surplus energy as a byproduct. This can be done by photoneutron transmutation, but the process has never been demonstrated on a full-scale system. Irridiation with fast neutrons of spent fuel can reduce the overall number of long-lived fission products, but because these products do not fission, a reactor with a high neutron economy is required. Even so, fast neutron irradiation is unlikely to completely eliminate fission products in spent fuel.

The most common method for disposal is in vitrified material. Vitrification is a process which produces which creates a solid, chemically inert material which is similar to a very high density glass. It is highly stable, is not easily reduced to a powder and is not soluble in water or nearly any other liquid. In general, the vitrified material is primary composed of non-radioactive materials which are used to help bind the radioisotopes. Thus, a few kilograms of radioactive material may be embedded in a cubic meter or more of vitrified material. This means that the resulting material is not as radioactive as highly concentrated radioisotopes would be. It is similar in properties to some minerals and is sometimes referred to as “synthetic rock.” Disposal of short and medium lived fission products in such a manner will result in a material which is immediately of minimal hazard and which will be equivalent in overall radioactivity to numerous natural minerals in a period of about 300 years or less. It is important to note that it will be significantly less radioactive long before this, however, than it started out as.

The case for reprocessing vs geological disposal of the entire spent fuel material:

To sum up the composition of spent fuel, this somewhat simplified graph illustrates the relative nature of the materials contained within the spent fuel assemblies:

It should be obvious that disposing of the entire assemblies is both wasteful and unnecessary. There are several methods which can be used to effectively manage the material from spent fuel in a manner which is more efficient manner.

Reprocessing - This is the most obvious solution to the waste issue. Reprocessing involves separation of the material into it’s chemical components, thus recovering the uranium and plutonium for use in fabrication of new fuel. The remaining fission products can be vitrified as waste or could potentially be used for medical or industrial isotope needs, depending on the circumstances. There are a few issues which exist with reprocessing. First, the process can be rather complicated and because of the possibility of contamination, it is necessary to have a well equipped and safe facility. This can involve an initially high investment. Also, although reprocessing does dramatically reduce high level waste, it does often produce additional intermediate level waste. This includes contaminated equipment and storage vessels. This waste is not really as much of a disposal hazard, but needs to be taken into account.

Despite the challenges, numerous examples exist of reprocessing programs which have proven to be both safe and beneficial to the overall fuel cycle. France, a nation which gets nearly all of its electricity from nuclear energy has a long-running reprocessing and isolation program which has resultes in an annual production of high density vitrified waste of about 160 cubic meters. Considering the size of the country and standard of living, this is a very reasonable and small amount of material.

The traditional method of reprocessing is aqueous reprocessing, such as the PUREX process. Although it has been successfully used for decades, newer methods, such a pyroprocessing, have demonstrated improved economics and could even be implemented onsite. Advanced reprocessing techniques can also reduce the possibility of secondary low-level waste.

Needless to say, the ecostupid movement opposes reprocessing of any kind in any circumstances.

Fast Neutron Reactors: The use of fast spectrum neutron reactors can greatly improve the effeciency of the nuclear fuel cycle as well as reduce overall waste. Fast reactors can be designed to breed fuel as fast as they burn it, thus allowing fuel rods to be used for much longer durations and thus reduce the volume of material to be processed. They can also be designed to efficiently burn plutonium and other minor actinide. Irradiation by fast neutrons can also reduce the amounts of fission products like iodine-129 and technetium-99, converting both to much shorter lived isotopes. The use of a fast neutron reactor may be part of a reprocessing program or may be used in a program that does not involve such reprocessing. Some fast reactor designs allow for many years of operation on a single fuel cartridge and produce less radioactive waste by re-irradiating the depleted materials.

Accelerator-based Transmutation: This procedure has not been demonstrated in full scale, but holds the promise of treating spent fuel in a manner which will render it safe for normal disposal and produce energy in the process. Sub-critical reactors have been proposed as a means of transmutating waste with neutrons, although this would not work with all of the isotopes present, due to the low neutron cross section of some. Another method, which would theoretically be able to address all materials present without the necessity of reprocessing and producing energy in the process is photoneutron transmutation. The company Nuclear Solutions has proposed a demonstration plant to transmutate nuclear waste using a 10MeV electron beam. Such a system would produce high energy gamma rays by secondary reactions, thus allowing for decomposition of radioactive atoms and production of surplus energy in the process.

Alternative Reactor Designs: While this would not be able to address the current spent fuel stockpiles alone, new reactor types can produce dramatically less waste and less hazardous waste. As mentioned, fast spectrum reactors can be used to destroy many of the long-lived radioisotopes, but other reactor designs can also have benefits in terms of waste produced. Higher effeciency reactors can burn the same fuel longer. This has been demonstrated by some advanced CANDU reactor designs. Thorium-cycle systems produce virtually no plutonium or other actinides and thus have much less long-lived byproducts. Spent fuel from such designs would be only need a few centuries to decay to bellow natural material levels, even without reprocessing. Other designs allow for onsite reprocessing or easier spent fuel management.

In conclusion, considering both the current technology which has been used worldwide to successfully manage spent fuel as well as new technologies which have been demonstrated or proposed, simply burying spent fuel seems both economical and ecologically foolish. Reprocessing and other methods can dramatically reduce the amount of material to be disposed of and also the total radioactivity. Burring spent fuel means one has to deal with the “worst of both worlds,” that is material which is both immediately high in radiation and which poses long-term disposal concerns. It is likely that the political reason for disposal by this method is simply opposition to nuclear energy, which would be bolstered by having additional fuel and reduced waste concerns. Of course, the Yucca Mountain plan is being protested too by the ecostupid movement, so it seems you just can’t win with them.


This entry was posted on Thursday, December 27th, 2007 at 1:06 pm and is filed under Bad Science, Enviornment, Good Science, Nuclear, Politics. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
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76 Responses to “What is spent fuel anyway?”

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  1. 51
    DV82XL Says:

            norrin radd said:

    I have no reason to doubt your expertise on this subject, and I will state flat out that I know next to nothing of it.

    However, several times you mention the coal lobby, which I think raises a very legitimate question-
    who signs your paycheck? By that , I mean, are you employed by a manufacturer or builder of nuclear plants, or a nuclear utility? If you work for a university, does the grant money paying for your research originate from an industry that has a financial interest in the expansion of nuclear power?

    Finally, I take issue with your use of terms such as “ecostupid” and your apparent demand that we “appeal to authority” and presumably accept the result at face value without further investigation. I’d like to point out that many people were around to see rivers catch fire due to chemical pollution, the near meltdown of Three Mile Island, Chernobyl… if people are concerned about accepting promises of corporations with profit at stake, it’s with good reason. It does NOT make them “stupid”. I’d say it makes them smart enough to proceed with caution.

    I have no “extreme agenda” here, nor am I dogmatically opposed to the use of nuclear energy. Indeed, I think we have little choice but to make good, informed use of it I simply have a desire to know more, and to get assurances that corporate interests are not blowing smoke up our collective asses once again so they can profit while the rest of us clean up the mess left behind.

    OK. It was me, not Doc that made the statements about the coal lobbies, and the appeal to authority. So I will answer for it.

    The coal lobby is actively against nuclear power because it is a competitor for base load generation. Up thread you will find a link to Rod Addam’s site were under the topic ‘The Smoking Gun’ he has been collecting evedence of this for some time now, I refer you there.

    The appeal to authority that I made was only in response to one of our regular sob-sisters who was guilty of exactly the same thing; trusting Greenpeace, because it’s Greenpeace. I was illustrating the error of that approach, which was made clear in subsequent entries.

    My background, which can be read in detail by clicking on my name, is that of an industrial chemist and metallurgist, and while I have never worked for the nuclear industry directly, I am qualified to make educated comments on the field. Nuclear energy (fission in particular) is not that mysterious or complicated, nether are the ancillary technologies that support it. Anyone with background in the sciences can understand it.


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  2. 52
    DV82XL Says:

            Poul-Henning Kamp said:

    JCredible sources claim that even if you just drop one slightly subcritical Pu-240 on top of another, for instance in a penthouse apartment, you will, apart from dying pretty instantly, have made for a really really lousy day at the DHS./phk

    Show us those ‘credible sources’ please.


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  3. 53
    Poul-Henning Kamp Says:

    I think the first time I saw it mentioned was in a Los Alamos publication from the late 1990ies, but I have not kept the exact reference.

    If you search for details on the critically accident at the “Siberian Chemical Combine” in December 1978, you can find the description of an accidental stacking of metallic plutonium of the kind we are talking about.

    From that description, any high-school physics student will be able to figure out how to make a mess which would send half the population of a metropolis into panic, once it gets reported on CNN.

    /phk

    PS: The other thing worth noting is that plutonium may not be as dangerous (“The worlds most poisonous substance” and all that) in the body as radium, from which its dangerousness was extrapolated. The Actinides Quarterly Journal had an interesting review of the “U-P-Pu” kohorte who seem to live on just fine, despite having Pu in their bodies from accidents during weapon production.


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  4. 54
    DV82XL Says:

    The technical problems confronting a terrorist organization considering the use of reactor-grade plutonium are not different in kind from those involved in using weapons-grade plutonium, only to a greater degree.

    • Technical Personnel.
    Competence and thorough understanding will be required in a wide range of technical specialties. These include: shock hydrodynamics, critical assemblies, chemistry, metallurgy, machining, electrical circuits, explosives, health physics, and others. At least several people who can work as a team will be needed. These will have to be carefully selected to ensure that all necessary skills are covered.

    • Costs.
    In addition to support for the personnel over a period adequate for planning, preparation and execution, a considerable variety of specialized equipment and instrumentation will be required, all or most of which need be obtained through controlled sources.

    • Hazards.
    Dealing with radiation, criticality, and the handling of, all present potential hazards that will have to be foreseen and provided against.

    • Detection.
    Assuming the operation is contrary to the wishes of the local national authorities the organization must exercise all necessary precautions to avoid detection of their activities. They would no doubt be faced by a massive search operation employing the most sensitive detection equipment available once it should be known that someone had acquired a supply of material suitable for use as a weapon.

    • Acquisition.
    Very early in the planning and equipment procurement phase the organization will need information concerning the physical form and chemical state of the fissile material it will have to work with. This will be necessary before they can decide just what equipment they will need. The actual isotopic content of the material may be undetermined until it is acquired, making preplanning difficult. The actual acquisition would entail dealing with the problems and hazards that would be set by the safeguards and security authorities.

    The point here being that this is a project that is unlikely to be within the grasp of a paranational organization, at the best of times, and given the poor performance of the one device that was tested by the U.S .using this isotope, a very low likelihood of the device assembling properly when fired.

    Ultimately, despite the fears of the West that such an attack may occur, the probability of one is vanishingly small – not when a semi or two filled with fertilizer and heating oil will yield a much greater explosion, more reliably and at a fraction of the cost.


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  5. 55
    Bill Jones Says:

    The world’s problems solved in one blog. Do you have any readers from Oak Ridge, yet?


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  6. 56
    Bubba Ness Says:

    To Ashton and other non-scientists. Here’s the way I explain it in class. Please pay attention.

    First, imagine every radioactive element has some amount of “natural gas” in it. Each different element has different amounts – some have a lot of gas per pound, and some have very little per pound. Radiation, is the by-products of burning that gas, such as carbon dioxide, carbon monoxide, and water.

    Some elements, burn their gas very slowly – like the pilot light on a stove – so it lasts a long time. Some burn it very fast, like the burner on a stove set to high. Some burn it in a way that it produces more of one by-product (such as carbon monoxide) than another.

    Now if you take an element that burns its gas slowly, it will burn for a long time, but it has a small flame will not burn you unless you directly touch it, and it produces very little quantity of by-products per day. An element that burns the gas fast, will heat the room, an will burn you, and produces a large amount of by-products per day. But that fast-burning element will run out of its gas in a much shorter time.

    Long-lived isotopes are generally not dangerous because they are burning like a small pilot flame, and are harmless to a human unless they hold it close to a delicate part of the body for a long time.

    Short-lived isotopes that produce the dangerous by-products are indeed more dangerous, but they are dangerous specifically because they are burning their fuel fast and thus emitting a lot of radiation. But their gas runs out quickly, and they are soon producing less of the dangerous by-product than the long-lives ones that burn slowly like a pilot light.

    Second, there are only a few radioactive isotopes that can be found in spent nuclear fuel, and they are nothing like the ultra-toxic things you hear about such as Polonium-210 used to kill the Russian. Ultra-toxics can come from certain types of nuclear explosions, and can be made in special laboratory environments, but not in your conventional nuclear reactors used for generating electricity, and they do not come from spent nuclear fuel.

    If you don’t follow this, or you think it is just scientific mumbo-jumbo or lies, check out France. Simple facts – France generates almost all of its electricity from nuclear plants. Yet the total of the hazardous waste from all of France’s nuclear electric plants per year doesn’t even fill up a tractor trailer container. Why? Because France reprocesses their spent nuclear fuel. President Jimmy Carter caved in to paranoid bad science when stopping reprocessing in the U.S. Ample subsequent studies have proven that the earlier fear mongering over reprocessing was essentially baseless.

    Please pay more attention to consensus, per-reviewed science than the Greenpeace (whose original founder quit because it was taken over by non-environmentalist socialists who simply use it as an anti-capitalists tool).


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  7. 57
    DV82XL Says:

            Bubba Ness said:

    To Ashton and other non-scientists. Here’s the way I explain it in class. Please pay attention.

    Good explanation. I’ll be pointing to it often, I think.


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  8. 58
    Dashing Leech Says:

    This is a really good article and refreshes my education on the subject from when I was in undergrad about 15 years ago.

    As far as the trolls in here, I have another perspective. I’ve been studying personalities and belief systems for some time and have come to understand that the issue here is about judgment processes. Sure, many people are rational and reasonable (“right brained”) and these people end up in many of the sciences and social sciences. But there is a large portion of the public that makes judgments through perceptive processes (“left brain”) instead of reason. They make judgments based on who’s “story” makes them feel better. That’s why the modern snake-oil industries are so profitable, such as “energy-based healing”. It is arguably why religion is so widespread as well.

    Human beings are attracted by great story-telling. When warm and friendly people tell them great stories, and about their heroic efforts to help the Earth and be in tune with nature, and that there are easy answers that the evil scientists and politicians are trying to hold down, there is a trust formed. The rational right-brain crowd tend to be poor at being warm, inviting, and at story-telling. The scientific method might be objective and rigorously come up with the right answers, but that makes it inherently cold and unfeeling. This attitude just fosters the image in the left-brainers’ minds that we are cold and uncaring.

    Having debated with left-brainers my whole life, it is quite apparent that proving them wrong is irrelevant to them and merely makes their impression of you even worse, thinking that you just like to argue and “just have to be right”. Insulting them just adds to that as well. When a left-brainer is convinced by someone they trust that 2+2 = 5, you can prove them wrong as many times as you want, but that just makes them dislike you even more, trust their source more, and remained convinced that 2+2 = 5 despite all evidence to the contrary.

    This sounds insulting, but left-brain thinking does have evolutionary advantages outside of finding objective truth. Evolution is driven by reproductive success, which is as much driven by social interactions that lead to reproduction as it is survival through improvement of objective knowledge. It’s difficult to measure, but it appears that left-brainers reproduce successfully at equal or greater rates than right-brainers, arguably due to a balance between their increased tendency to reproduce at all with their reduced success from ignoring the best objective information. (For example, children are less likely to survive if their parents use prayer instead of medicine or listen to Jim Carey and Jenny McCarthy about not giving inoculations due to unwarranted fears.)

    So we can’t just dismiss left-brainers. They are a large part of the population, potentially a majority, and as such have some power over policy in a democracy. What we right-brainers need to do is learn how to better communicate with left-brainers. We need warm and friendly scientists who are good at story telling to be the promoters of science and perform the education of the public on these topics. We need more people like Richard Feynman and Carl Sagan. Even Stephen Hawkings is quite decent because of the compelling drama of his life. David Suzuki isn’t too bad either, but I’ve been greatly disappointed that he has associated himself with activist organizations, including Greenpeace that promote anti-intellectualism, over consensus building within the scientific departments and circles that the government actually listens to. He has set himself up for failure and ridicule by doing so even if he has the right information.

    This might be a long aside about personalities, but I think it is as important that scientists understand their audience as much as the audience understands the science. And since the scientists old and young in here seem impressively rational, I hope you can understand our need to change our public face. I don’t know the best way to start a movement in that direction, but even one person at a time is a start.

    I’ll definitely be reading more here. The information density is quite high while not appearing to talk over everyone’s head. Good job.


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  9. 59
    DV82XL Says:

    Regrettably, Dashing Leech, you have made a valid point, and one worth taking into consideration.


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  10. 60
    Eric Says:

    There is at least 1 spent fuel reprocessing plant in the United States that never went into full operation. The facility was built by GE and got contracts from nuclear facilities to accept their spent fuel, anticipating that they would be able to resell the fuel back to the nuclear plants.

    After they got the contracts and during final construction of the facility Carter made reprocessing illegal, yet GE is still responsible for accepting the nuclear waste from the nuclear reactors they contracted with. Now the facility has spent fuel sitting in swimming pools indefinately because they have nothing to do with it.

    I toured the facility years ago, and that’s when I learned about Carter’s decision. This desperately needs to be overturned…why hasn’t it already been done?


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  11. 61
    Ugly American Says:

    There are geothermal plants that have been in operation for over 100 years and sell their power for $0.01 a kWh & there are wind turbines selling power for $0.03 a kWh but the very best the nuclear industry can even promise is $0.07 a kWh if they get subsidized financing & the government pays for all the waste internment for the next 10,000 years. The Yucca dump is now expected to cost taxpayers $90B and isn’t even finished yet.

    Nuclear apologists like to claim reactors cost $1B when in fact Browns Ferry 1 took $2B just to fix and the industry’s own numbers project new reactors would cost $6B if they start now and nothing goes wrong while Moody’s Investors Service estimate the true cost at $7B unless something goes wrong.

    Read the MIT study on geothermal power. We have a 30,000 year supply. Read the nuclear industry study on worldwide U235 reserves. The entire world only has 80 years at the current rate of consumption and people are talking about doubling or tripling the number of reactors. They’d run out of fuel before they were even paid off.

    That’s why private investors won’t build reactors with their own money – only taxpayer money.


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  12. 62
    DV82XL Says:

            Ugly American said:

    There are geothermal plants that have been in operation for over 100 years and sell their power for $0.01 a kWh & there are wind turbines selling power for $0.03 a kWh but the very best the nuclear industry can even promise is $0.07 a kWh

    And of course wind isn’t subsidized, and dry-rock geothermal is cost effective and you have the references to back this up.

    We’ve heard it all before, it never comes with complete numbers.


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  13. 63
    Finrod Says:

            Ugly American said:

    There are geothermal plants that have been in operation for over 100 years and sell their power for $0.01 a kWh & there are wind turbines selling power for $0.03 a kWh but the very best the nuclear industry can even promise is $0.07 a kWh if they get subsidized financing & the government pays for all the waste internment for the next 10,000 years. The Yucca dump is now expected to cost taxpayers $90B and isn’t even finished yet.

    Nuclear apologists like to claim reactors cost $1B when in fact Browns Ferry 1 took $2B just to fix and the industry’s own numbers project new reactors would cost $6B if they start now and nothing goes wrong while Moody’s Investors Service estimate the true cost at $7B unless something goes wrong.

    Read the MIT study on geothermal power. We have a 30,000 year supply. Read the nuclear industry study on worldwide U235 reserves. The entire world only has 80 years at the current rate of consumption and people are talking about doubling or tripling the number of reactors. They’d run out of fuel before they were even paid off.

    That’s why private investors won’t build reactors with their own money – only taxpayer money.

    Utter garbage.

    The assertion that private enterprise is unwilling to risk capital to build nuclear power plants is an outright lie.

    The projected price of all power generating infrastructure has been rising with rising global demand for the materials necessary for any major industrial plant. In comparison with other power sources, nuclear fission still trumps everything else.

    The amount of nuclear fuel (uranium and thorium) present in the Earth’s crust and recoverable is sufficient to last us for as long as the sun remains on the main sequence.

    Even if large-scale geothermal power becomes practical, it will be utterly marginal compared to the capabilities of nuclear fission. No one in their right mind would build a geothermal plant when the mature nuclear alternative becomes available.

    Wind and the rest has been sufficiently well debunked elsewhere to make any statement here redundant.


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  14. 64
    Neurovore Says:

    All political arguments about the reprocessing of spent fuel aside, could reprocessing of nuclear fuel ever actually hope to compete on an economic basis with simply mining more uranium? As far as I understand it, mining fresh uranium ore is still much cheaper than actually reprocessing spent fuel which is part of the reason why there is not much enthusiasm for lifting the idiotic ban on nuclear fuel reprocessing that Carter imposed during his administration.


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  15. 65
    George Carty Says:

    Isn’t that the main argument used by supporters of the LFTR – that is is far more economical to operate because it does its own reprocessing?


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  16. 66
    drbuzz0 Says:

            Neurovore said:

    All political arguments about the reprocessing of spent fuel aside, could reprocessing of nuclear fuel ever actually hope to compete on an economic basis with simply mining more uranium? As far as I understand it, mining fresh uranium ore is still much cheaper than actually reprocessing spent fuel which is part of the reason why there is not much enthusiasm for lifting the idiotic ban on nuclear fuel reprocessing that Carter imposed during his administration.

    It depends on a number of factors, like the method of reprocessing and scale. Areva says that they can do it at a price that is on par with new fuel. However, it makes more sense if you include the savings in disposal and not just the price of new fuel. When you consider the ridiculous amount of money sunk into Yucca Mountain and the whole disposal backend then the reduction in spent fuel improves the economics of the process dramatically.


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  17. 67
    Soylent Says:

            George Carty said:

    Isn’t that the main argument used by supporters of the LFTR – that is is far more economical to operate because it does its own reprocessing?

    It depends on a lot of things.

    It depends on the reprocessing method(purex is awful; it gives you liquid waste and produces pure plutonium, which will be weaponsgrade if LWR fuel that has been in the reactor a short amount of time is used). It depends on your goal(e.g. producing plutonium to seed LFTRs from spent LWR fuel, producing MOX fuel for LWRs, extracting valuable platinum group metals from spent fuel etc…). It depends on what kind of spent fuel you are reprocessing and how long the fuel that you’re reprocessing has been allowed to cool. It depends on the cost of producing uranium from lower grade deposits and sea water. It depends on how low the cost of reprocessing can be made using newer technologies. It depends on how cheap safe storage of fission products can be made after they have been liberated from the uranium oxide ceramic(e.g. through glassification).


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  18. 68
    Paul Eckerson Says:

    The basic problem with our government is that they won’t do anything tha makes voters angry enough to vote them out. So if you make enough noise (just like spoiled children) you will get your way. Everyone with any basic science education knows this problem needs to be addressed and the science community should be left to resolve the problem. All this stored fuel at current reactor sites is a far greater threat as a terriorist target than the danger posed by the Yucca Mountain plan. I too agree that any new reactors built ought to be designed to minimize radioactive byproducts with the best current proven technology and reprossesing current ought to be employed. Look what France is doing!
    In otherwords, the cost of disposal needs to be factored into the cost upfront. This approach in fact ought to imposed on all products. If we put the cost of disposal into products, companies will design products to eliminate waste, disposal and environment impact. No government laws would be needed.


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  19. 69
    Lars Says:

    For the chemists in the audience.
    In most LFTR designs the first step in processing the fuel is to extract U, Np, and Pu and put it back into the reactor. This is done by fluorination. Pu is tougher but ORNL showed it could be done. The process is normally expressed as being able to remove 99%-99.9% of the U and Np and 90%-99% of the Pu.
    But I’m wondering if this is the right way to look at things.
    I’m thinking if we start with a higher Pu concentration then we need to plan on a second pass through the fluorinator to do a good job of removing the Pu. So rather than thinking of it as a percentage remaining it is a residual amount that remains and higher initial concentrations mean multiple passes to remove it. Is this correct? If so, how can I estimate what the residual amount is?

    I’ve done some analysis of the waste flow and it is dominated by the waste that leaks through the processing. I’d like to understand how much we can reduce this.


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  20. 70
    drbuzz0 Says:

    Hi Lars. Yes, the LFTR is a very elegant design. I’m not sure that plutonium should really be that much of a concern, because unless you add plutonium or U-238 from the beginning, perhaps in order to burn it or something, then there should be pretty negligible amounts of plutonium produced. The only way you’d get plutonium would be to have either U-233 absorb a neutron and not fission (which is a small percent) to produce U-234, which would absorbe a neutron to produce U-235, which will also usually fission. If U-235 does not fission upon absorbing a neutron you have U-236. U-236 has a small cross section and will usually just sit there but with enough irradiation a small portion will absorb a neutron and then rapidly decay by beta emission to Np-237.

    That’s quite a chain of low percentage interactions to get all the way to Np and then Pu. I’d therefore have to assume that any amount of transurics would be extremely small.


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  21. 71
    Lars Says:

    The inventory inside the reactor for an LFTR running a Th/U cycle is 350 kg of Pu. When we start up it is closer to 8,000 kg whether we start with u235 (20% LEU) or TRU’s. So, I’d like to reduce as much as possible the Pu that flows to the waste. With lots of power plants world wide the flow still adds up to something noticeable.


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  22. 72
    arcticcc Says:

    You know, fusing these materials into inert form and storage in the desert is a perfect solution. We can easily give up 40 sq miles of Nevada for this storage. What so many of the folks here dont think of is that these are our grandchildrens raw materials. It is wastful and arrogant to think of the oft stated but horribly expensive solutions of drop in the ocean trenchs, bottoms of old mines/ wells, shoot it to the sun.
    Just like the plastics that were burned off as waste in the early days of oil production, or the landfills / aluminum mines of our future.
    We need to be more aware that the future generations will appreciate us leaving our “waste” for them.
    mv


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  23. 73
    George Carty Says:

    I just happened on this thread again, and Dashing Leech’s comments about left-brainers and right-brainers (hmm, has he got them the wrong way round? I thought that left-brainers were the rationalists…) reminded me of the Why We Fight World War II propaganda films.

    These films (plus some other US propaganda films of the same era – Here Is Germany for one example) used two narrators (Walter Huston and Anthony Veiller) with very different styles. Perhaps this was done in order to appeal to both personality types…


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  24. 74
    Shafe Says:

    There’s a lot of talk about “nuclear waste” and what should be done with it. There are different categories of radioactive waste which include everything from very low level material like contaminated lab coats and beakers from radiological tracers all the way up to highly concentrated high-energy radiation sources.

    Do the solvents used in the refining, enrichment, and reprocessing of nuclear fuel represent a major waste stream? Numerous 80′s era movies use the image of hundreds of 55-gal. drums full of liquid “nuclear waste” deteriorating and leaking or being dumped into the sea by malevolent corporate types. What is the actual fate of these solvents? Are they reclaimed and reused? Are they rendered harmless somehow?


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  25. 75
    Fat Man Says:

    This thread is still leaking comments to the e-mail system. Is there any way to close it?


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  26. 76
    drbuzz0 Says:

            Fat Man said:

    This thread is still leaking comments to the e-mail system. Is there any way to close it?

    What do you mean “leaking comments to the e-mail system”

    Do you mean you signed up for email notifications on it?


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