Do the math – Secure fissile materials inside reactor cores

The Bulletin of the Atomic Scientists has just published an open letter to President Obama that offers opinions on how to solve various pressing problems.

I’d like to riff on that letter and suggest that we should be pursuing ways to use one problem to solve another one. According to the BAS, there is a pressing need to secure fissile material stockpiles and a pressing need to effectively implement measures that will reduce the amount of CO2 that is dumped into our common atmosphere, raising the serious risk of global climate change.

Despite the title of the publication, however, no one who signed that letter effectively lobbied the other signers to acknowledge that the solution to one problem would also provide a useful tool for solving the other problem. Since James Hansen was one of the signers, I was disappointed to see that the letter’s climate section does not even mention nuclear energy. (Knowing a little about other signers, I did not expect very much on that topic, but Hansen is normally an effective advocate who presses a rational approach that includes a strong dose of passionate information sharing.)

Fissile materials – generally highly enriched uranium and plutonium – are the fundamental enablers of atomic fission power plants. In December 1953, Dwight Eisenhower, my favorite president of the 20th century, spoke about fissile (fissionable) materials and their possible utility:

Who can doubt that, if the entire body of the world’s scientists and engineers had adequate amounts of fissionable material with which to test and develop their ideas, this capability would rapidly be transformed into universal, efficient and economic usage?

We’ve never tried making fissile materials accessible to engineers and scientists tasked with transforming them into universal, efficient and economic usage. The importance of taking that path towards widespread energy abundance increases every day.

According to the open letter, which references a recent inventory report, the world’s current stockpile of fissile materials includes 1,440 tons of HEU and 500 tons of separated plutonium. I cannot think of a more secure and useful location for that material than inside the cores of operating nuclear power plants with their self protective radiation fields and necessarily thick walled pressure vessels and containment shields serving as vaults.

Here is an open source math exercise for Atomic Insights readers. Imagine about how you would best use that fissile material to fuel your favorite style of fission power plant and then calculate how many plants you could fuel and how much of the world’s total energy consumption those plants might be able to provide. Provide your suggestions and your work.

(Unlike 350.org, which has apparently initiated a “Do the Math” speaking tour without offering any math to speak of, many readers at Atomic Insights are not afraid to do a little math in their pursuit of reasonable and effective solutions to pressing problems.)

About Rod Adams

55 Responses to “Do the math – Secure fissile materials inside reactor cores”

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  1. Cyril R. says:

    Times were different in the 50’s and 60’s. There was so much optimism and constructivism everywhere.

    Today, that spirit is gone. Today’s it’s all no-can-do, this is bad, that is bad. Obama’s the only one that says “yes we can” but not much actually comes of it since everyone else feels less strong about it when push comes to shove.

    • SteveK9 says:

      China? Russia?

    • donb says:

      With regard to nuclear energy, the working regulatory mantra is “You can never be too safe.”

      The problem is, this is the narrow view, i.e., nuclear energy needs to be made as safe as possible.

      When an wide, overall view is taken, this approach becomes nonsense. It is nonsense to restrict the use of nuclear energy (for “safety” reasons, of course), making it seldom used, so that more dangerous energy sources (coal, gas, oil) are used instead.

      The net result is that we have a regulatory system that is supposed to increase safety winds up decreasing safety.

  2. Jason C says:

    Ok, here’s my crack at it. Granted my figures are kind of rough.

    Assuming the HEU is 90% grade U235, the 1440 tons would contain 1296 tons of U235.

    Assuming a 1GW reactor takes 100 tons of 3.5% grade (3.5 tons of U235) to produce 8,760 MWh’s (or 8,760,000,000 kWh’s) per year @ 100% capacity.

    We could then simply 1296/3.5 to get enough to supply 370.3 1GW nuclear reactors for one year. Or enough to roughly supply all of the USA reactors for 3-4 years. We could shave 10-15% off that end figure to conservatively account for capacity factors.

    If we use a baseline of say 6 cents per kWh, then each reactor could gross about $525 million per year, or about $194 billion dollars for all the reactors. I think that could pay for the gathering effort plus a some more new nuclear power plants.

    Then again, I could be wrong. I rarely trust my own math, but at least I take a crack at it.

    • Cyril R. says:

      Some corrections.

      old LWRs need almost 300 tonnes natural uranium per GWe-year.

      That contains 2 tonnes of U235. So it’s 648 GWe-year.

      But it’s better with newer LWRs, having deeper burn and higher electrical efficiency. Plus if you start off with HEU you don’t lose U235 in the enrichment facility that you have with mined uranium. These factors could stretch the production to over 800 GWe-year.

      Wasting all that enrichment effort in downblending into LWR fuel is something I don’t like however. I would prefer to make U233 for the thorium cycle with the HEU, in a fuel cycle that doesn’t ever seperate actinides.

  3. Josh says:

    Agreed Rod. The core of a nuclear reactor is about the best place to put these materials, making theft an impossibility and providing clean, large-scale electricity to society. It would be a shame to waste such a valuable resource.

  4. Chuck P. says:

    Several months ago, I dug around the BAS website looking for their take on the megatons to megawatts program. You’d think that they would be shouting it from the rooftops. It is after all, the greatest example of beating swords into plough shares in human history. I failed to find even a single mention of the program. After that exercise, I find it impossible to take the BAS seriously.

  5. Cyril R. says:

    Ok I will add one of my suggestions.

    1440 tons HEU and 500 tonnes WgPu. Let’s call that 1750 tonnes thermally fissile material.

    @ 2.5 ton fissile/GWe, this material can be used to start 700 GWe of low power density single fluid molten salt converter reactors. The type that doesn’t have fuel processing and two fluid barriers so low tech, shovel ready (well very nearly so).

    But actually these reactors require a small feed of fissile to compensate for the burner design (not a breeder). Still it does pretty well in that category, as thorium burns well in thermal spectrum, needing only some 0.3 ton of fissile HEU/WgPu feed per GWe-year.

    So we’ll start up some 200 GWe and run these for 20 years. They require 2.5×200 = 500 tonnes fissile to start up. And 0.3x20x200 = 1200 tonnes in feed. We’ll get 4000 GWe-year.

    And importantly, we also get a lot of valuable high quality U233, yet with a bunch of U232 to deter proliferation. The plutonium has also been denatured by the Pu238 made by the thorium cycle, so the plutonium is also useless for weapons.

    The U233 could be recovered by vacuum distillation, so it’s never seperated as a pure uranium stream (some fission products and carrier salt comes along, making direct weapon use impossible altogether).

    The next stage could possibly be a two fluid LFTR fleet, needing 1 ton fissile U233 (or the equivalent in some U mix that has evolved by then) that we’ve created per GWe to start up.

    I’m thinking we should have enough fissile uranium by then (3 ton/reactor) to start up some 600 GWe of LFTRs.

    Some of these LFTRs would perhaps replace the single fluid cores as the rest of the plant is still good to go (only 20 years old). Alternatively the single fluid cores could continue on mined uranium.

    • Cyril R. says:

      Forgot to mention that the 600 GWe of LFTRs will last as long as we want without further fissile makeup. The reactors could run for 60, maybe 80 years. Then the fissile uranium and carrier salt is all taken out to a new LFTR. The engineered plant gets decommissioned, the fission products are vitrified, but the actual reactor core itself, fuel and carrier salt in all, lasts just about forever, living on in a next generation reactor. No more fissile needed. Just add thorium, and stir.

      600 GWe is a lot, considerably more than the USA electric demand (500 GWe of nuclear would do it).

      If we wanted to power the world, though, weapons materials aren’t enough. We’d have to dig into the stockpiles of spent fuel transuranics. Today’s reactors make roughly 300 kg of TRUs/GWe-year. Meaning well over 100 tonnes of TRUs per year.

      We could use a lot more than that if we want to have 10,000 GWe of nuclear generation globally by the end of this century.

      Contrary to what some environmentalists would have you believe, we actually don’t have enough spent fuel plutonium yet. We’ll need a lot more LWRs, several thousand GWe at least, to generate the startup fuel for the next generation of reactors.

      That’s not a bad thing, as we can continue to build light water reactors and feel good about it.

      • Andrew Jaremko says:

        Rod – thanks for the post. Cyril R. – thanks for doing this arithmetic, and pointing out that we do need a lot of fissile for startup charges for converter and breeder reactors. I’ve been thinking that we could use strategically placed fast breeders optimized for fissile generation, to feed the small modular reactors that are going to be rolling off the assembly line. Co-locate the SMR factory (and other factories) and the fuel generator and make good use of the power that’s a by product of generating nuclear fuel! Think big!

      • Engineer-Poet says:

        Today’s reactors make roughly 300 kg of TRUs/GWe-year. Meaning well over 100 tonnes of TRUs per year.
        We could use a lot more than that if we want to have 10,000 GWe of nuclear generation globally by the end of this century.

        IIUC, whether we need TRUs depends on what we’re trying to do.  Running fast-spectrum reactors on a U/Pu cycle works well with TRUs.  Thermal-spectrum Th/U, not so much.

        I’ve previously proposed a fleet of sPRISMs using radial DU breeding blankets to sustain themselves, and axial Th breeding blankets to generate LFTR startup charges (or perhaps DMSR maintenance fuel).  The high fissile load for fast-spectrum reactors means that this is a relatively slow way to grow nuclear power through breeding alone.

        • Cyril R. says:

          Running fast-spectrum reactors on a U/Pu cycle works well with TRUs. Thermal-spectrum Th/U, not so much.

          Actually it should work well, as long as the cycle itself (fertile) is on thorium. TRUs aren’t too good a fuel in thermal spectrum, but you can add some makeup fuel to cover that up. Later on the cycle turns largely to U233 (assuming deep burn such as DMSR could achieve) which runs well in thermal spectrum.

          There is some concern over trifluoride solubility in molten FLiBe, but only with high power density cores. A low power density converter wouldn’t be bothered much.

          There is concern over how to reprocess TRUs as trifluorides. They’ll want to go where the lanthanide trifluorides go, and thorium is slutty enough to want to come along with either TRUs or lanthanides.

          This is bad, in a reprocessing design. But not a concern in a converter that doesn’t process fuel.

          Hence my interest in TRU started, TRU fed deep burn Th converters.

  6. Shaker Cherukuri says:

    From what I understand very few countries do re-processing of spent fuel – France, India and Russia for example. US may have something in the works but does not currently re-reprocess spent Nuclear Reactor fuel. It does re-process fuel from weapon systems.

    • Cyril R. says:

      Some countries make MOx fuel but it isn’t sensible. Spent MOx fuel from light water reactors – basically just one extra pass of the plutonium – doesn’t help much in reducing actinide waste nor improve prospects for future generations. Basically, spent MOx fuel has poor quality plutonium left, not much economic use for future advanced reactors.

      If we are serious about those future reactors, it makes sense to stop wasting money in making MOx fuel now, and divert the wasted money into building demo plants for the advanced reactors (LMR, DMSR, LFTR).

  7. Brian Mays says:

    At least Hugh Gusterson didn’t sign the letter. ;-)

    Here are some numbers for using only the uranium in a conventional 1000 MWe PWR, such as those operating in the US today.

    Assumptions:

    The plan for the Megatons to Megawatts program was to blend down 500 tonnes of weapons-grade HEU to 15,250 tonnes of 4.4%-enriched LEU. They use re-enriched depleted uranium tails to do the down-blending, so not all of the U-235 in the fuel comes from the weapons material.

    The assumptions for the plant are a thermal efficiency of 33% and a rather modest burnup of 45 GWd/t.

    Thus, 1440 tons of HEU would produce about 1620 GW-years of electricity.

    To put this in perspective …

    This is more than the output of the entire US nuclear fleet from 1993 to 2011.

    This is the total electricity generation in the US from mid-2008 to the end of 2011.

    This is the output of the entire world’s nuclear plants over 6 years.

    This could provide an entire lifetime’s supply of electricity (according to today’s consumption levels) for 14.5 million Americans or 76 million Chinese.

    It would eliminate the need to mine somewhere between 30 million and 600 million tonnes of uranium ore, depending on the grade.

    It would save 14 billion tonnes of carbon dioxide emissions if replaced by coal or 8.4 billion tonnes of carbon dioxide emissions if replaced by natural gas.

    The next generation of reactors, which are being built today, can do better than this.

    • EL says:

      Brian Mays wrote: “To put this in perspective …

      This is more than the output of the entire US nuclear fleet from 1993 to 2011.

      This is the total electricity generation in the US from mid-2008 to the end of 2011.

      This is the output of the entire world’s nuclear plants over 6 years.

      This could provide an entire lifetime’s supply of electricity (according to today’s consumption levels) for 14.5 million Americans or 76 million Chinese.”

      To put this in a broader perspective, global primary energy consumption is 28,720 TWh and rising to 30,479 TWh in 2035. The challenge of powering a planet on such a fuel source is immense. Assuming we are running nuclear as load following plants, we’re getting a reduced capacity factor (77% is what they get in France). Your 1620 GW-years of electricity is some 10,927 TWh (or 38% of current global primary energy needs for a single year in 2011). In terms of serving the global population with low carbon energy alternatives, that’s a drop in the bucket that is quickly eclipsed by rising demand and the hunger for of developing economies for new energy resources. Getting close to 55% of global energy production from nuclear would be a very challenging and ambitious goal indeed (and would require a scale of fuel production some 37 times the fuel inventory in your example, and would cover only 55% of our consumption needs for 24 years).

      Doable, but it’s not particularly sustainable, meets a little over half our demand, and would require a massive and coordinated global effort in new reactor construction and international fuel cycle development previously unseen (and perhaps even unimaginable to many) to get us there. Do you want to review the environmental, global security, and human health cost (RECA and EEOICP) of obtaining just 1/37th of this fuel inventory in the first place? In addition, EIA says we’re heading in the wrong direction (nuclear drops 2% in share of global electricity mix from 2011 to 2040, and is unable to keep up the pace with rising consumption). These are staggering numbers. And we have no coordinated global energy strategy to meet them.

      • Cyril R. says:

        We are definately heading in the wrong direction. This has nothing to do with the actual environmental impact of nuclear, which is very small even at the 10,000 GWe level. Importantly, it’s smaller than any other generation alternative, including solar (try running some numbers on how much mined stuff you need for PV and energy storage at this level).

        It even has nothing to do with nuclear fuel sources, since high EROEI uranium is available to power 10000 GWe of LWRs for 26000 years (about 40 billion tonnes mineable at EROEI >10, 150 ton/GWe-year with low tails assay and high efficiency steam generators and turbines).

        We are heading in the wrong direction because of political choices that have been made long ago. For example, building nuclear plants in most countries is outlawed. It’s forbidden, in the same category as raping someone. Not allowed, punishable by imprisonment.

        The challenges of alternatives that are allowed, like photovoltaics, are far bigger. For example, just replacing one EPR unit in my country would need 70 MILLION large solar panels, plus I don’t know how many millions of batteries. And they’d still be pointless sitting about in winter.

        • EL says:

          Cyril R. wrote: “It even has nothing to do with nuclear fuel sources, since high EROEI uranium is available to power 10000 GWe of LWRs for 26000 years (about 40 billion tonnes mineable at EROEI >10, 150 ton/GWe-year with low tails assay and high efficiency steam generators and turbines).”

          Where are you getting 40 billion tonnes?

          WNA puts known recoverable reserves at 5.4 million (US$ 130/kg U), 7 million (US$ 260/kg U). At your rate of 150 ton/GWe-year, this isn’t going very far in LWRs (and not if we’re taking on primary energy consumption as well). Presumably, if we want to have any impact on climate change we’re going to have to tackle primary energy (standing at 30,479 TWh in 2035). At your rate of 150 ton/GWe-year (and 77% CF for load following generation), we’re going to get 6.746 TWh/year out of each 1 GWe nuclear plant. We’re going to need 4518 plants to cover the load (we currently have 430), and we’re going to exhaust known recoverable reserves in 10.3 years (using LWRs, higher US$ 260/kg fuel cost, and assuming consumption never rises above projected 2035 levels).

          Am I missing something?

          Duly noted … this is a very large amount of energy. But if uranium supplies are as unsustainable as they appear above (we have been even slower bringing breeders to market, LFTRs are non-existant), why not select an energy resource that appears to be cost competitive in 20 to 60 years, has no fuel component, and is sustainable as long as there is human life on this planet (and for every nation despite national security concerns). And yes, the material and environmental footprint needed for such an expansion are very great (and I never suggested they weren’t)?

          Just to be clear … I’m not arguing for a 100% renewables alternatives. But if we’re interested in absolute contrasts, this appears to be it!

          • Cyril R. says:

            Some 8 x 10e11 tonnes of uranium are available at EROEI >16. It is not a question of existing prospecting for high density ores, it is a technological and geological question.

            http://nextbigfuture.com/2009/02/revisiting-duration-of-nuclear-power.html

            in the 1960s people were worried about uranium running out in the 1970s. In the 70s they worried about running out in the 90s. In the 90s people worried about running out somewhere half into the 21th century. This is because people have conflated reserve to production ratios with what’s in the ground. This travesty is still happening, even by respected organisations; apparently in some practices, we never learn.

            Wind and solar do have a big fuel cost component – they need a lot of natural gas or coal to back them up. Actually the word backup is not fair, since we’re talking about more fossil kWhs in backup than actual wind and solar kWhs

          • Cyril R. says:

            I should also point out the good example of this graph showing reserves over time.

            http://www.world-nuclear.org/uploadedImages/org/info/Known-uranium-resources-and-expenditure.GIF

            As more exploration money was invested (not really all that much either, tiny per GJ uranium found) more uranium was found.

            Who knew? Apparently it is a difficult concept for most. Run hundreds of nuclear reactors for decades on mined uranium, and end up with more uranium resources than you started out with.

            We haven’t scratched the surface when it comes to mining uranium.

          • Brian Mays says:

            why not select an energy resource that appears to be cost competitive in 20 to 60 years, has no fuel component, and is sustainable as long as there is human life on this planet (and for every nation despite national security concerns).

            But slaves still need to eat. I’d consider their food to be “fuel.”

          • Engineer-Poet says:

            why not select an energy resource that appears to be cost competitive in 20 to 60 years

            Because in 20 years we could have a fleet of LMFBRs burning our SNF and DU, started on the actinides in our SNF.  Once the DU is gone they can run on uranium recovered from seawater (200x the EROI of feeding a LWR cycle), which is replenished by rivers at some 30,000 tons/year; all human primary energy demand can be met by only 5000 tons/year.

            There are no technical hurdles for liquid sodium reactors, just political.  Contrasting this to the massive improvements in materials and electrochemistry for “renewables”, the correct path forward is obvious.  Wind and PV likely have places, but they need to prove themselves first.

          • EL says:

            Brian Mays wrote:”ELHere’s another hint for the future. Don’t compare energy in the form of electricity to primary energy, unless you want to demonstrate that you really don’t have the first clue.”

            Duly noted.

            Briam Mays wrote: “The reference that you cite gives total primary energy consumption as only 98 quads in 2011 and 104 quads in 2035, and these figures are for the US, not the world.

            Thank you again. Global power consumption (from all resources) was 20,181 TWh in 2008. If we’re going to be using global uranium reserves or decommissioned weapons stock (I still don’t know how you wish to calculate this), we’re still only talking decades (and not generations). And yes, we can do more enrichment work, separate plutonium and uranium from spent LEU, and develop 10 or 20 thousand fast reactors that can be run on a commercial basis, but we’re still up against some major headwinds (low public approval, siting limitations, global security risks, international regulatory regime, new resource constraints, public and private sector financing, and availability of cost competitive alternatives).

            Where are we with fast reactors … this seems to be the real discussion to be had (and not just kicking the can down the road with the status quo, and ticking-off every other interest group, consumer, and potential ally in the process). And when consumption is 10 times what it is today in 100 years, what do we do next … just keep building fast reactors (one in every neighborhood or in the basement of every home) and move the goal post another 100 – 200 years? Techno-utopian visions are just as unrealistic and unworkable as social and political ones?

            Perhaps we need look more practically at our objective physical circumstances and life historical trajectories (to borrow a term from Marx), and understand that there are limits to human circumstances and potential. Are we mostly consumers and engineers, and growth is our “life project,” or is “balance” a goal to be had (and our “mind” the best available tool to arrive at equitable, fair, and relative “happiness”). I look at this chart:

            http://www.theoildrum.com/files/world-energy-consumption-by-source.png

            And realize something has to change. Nuclear is not going to be doing all of the “heavy lifting” in this long term scenario. I am pretty certain of this. Then where does this leave us as community, nation, species, and planet?

          • Rod Adams says:

            @EL

            Most of the disadvantages that you ascribe to nuclear energy (low public approval, siting limitations, global security risks, international regulatory regime, new resource constraints, public and private sector financing) can all be fixed by decisions made by human beings. They are, in large part, due to a sustained failure on the part of people who understand the technical advantages of nuclear energy to make those benefits abundantly clear to customers. I am not talking just about marketing, but also about certain technical decisions that have reduced the benefits to the point where nuclear is viewed as being just one more option with even more baggage instead of being a power source that is orders of magnitude superior to all other options. (I believe that the fundamentals are there to support that statement – waste volume small enough to effectively store without environmental releases and energy density that is two million times greater per unit mass than the next best competitor (oil).)

            On the other hand, the disadvantages that hamper the development of wind and solar are inherent in the power source. The sun reliably disappears for a large portion of the time when people need to use energy. The wind is only available on an irregular basis except in very limited areas of the world where geography and trade wind patterns improve its reliability to the point where no one wants to live there. Even perfect collection systems cannot overcome the basic input problems associated with wind and solar energy. (Wave and geothermal are even more limited.)

            The point that many of the nuclear advocates want to make is that nuclear CAN do the heavy lifting and that it is only a matter of choosing to learn how to do it better.

            I have no problem living in a society where people freely choose to use less and to consume less. I have a real problem with making plans for future production that FORCE that behavior onto people because of some mistaken notion that there is a fixed limit to growth somewhere.

          • Engineer-Poet says:

            when consumption is 10 times what it is today in 100 years, what do we do next

            You do realize that fast reactors are roughly 200x as efficient as LWRs at converting natural uranium to energy, don’t you?  (About 100x as efficient as HWRs.)

            As I’ve noted before, the total primary energy consumption of humanity could be fed by the fission of about 5000 tons of uranium per year.  Uranium can be recovered from seawater for under $200/lb, and rivers carry some 30,000 tons to the oceans each year.  That is $200 million dollars a year for all the feedstock humanity needs at our current level of consumption, and it is renewable for as long as Earth has a hydrological cycle (meaning, as long as Earth remains habitable to humans).  What’s not to like?

            just keep building fast reactors (one in every neighborhood or in the basement of every home) and move the goal post another 100 – 200 years?

            Look back 200 years, or even 100, and tell me if they could have appreciated our problems or capabilities.  Aside from folks like Tyndall and Arrhenius just a century ago, I doubt they would have understood even the basics.  The best gift we can leave to our posterity is a functioning ecosystem, and a few radioisotopes are nothing to that compared to a massive overload of CO2 and toxic heavy metals.

            And realize something has to change. Nuclear is not going to be doing all of the “heavy lifting” in this long term scenario. I am pretty certain of this. Then where does this leave us as community, nation, species, and planet?

            Without you spelling out what you mean, you leave the burden upon us to speculate and then answer your unasked question.  That’s unfair.

            What nuclear energy can do is stop the flow of fossil carbon into the atmosphere, and reduce the impacts of energy production by slashing the amount of land area it affects.  Nuclear technologies already tested (but not in production) can help serve other human desires with smaller impacts, such as thermochemical conversion of abundant low-value materials to fuels and high-value chemical feedstocks.  Nuclear energy can let us live as well or better while shrinking our footprint.  Again, what’s not to like?

          • Engineer-Poet says:

            Excuse me, that $2 billion a year for enough uranium to satisfy humanity’s primary energy consumption.  I was off by a factor of 10.

      • Brian Mays says:

        EL – Wow, talk about missing the point by a wide margin!

        Nobody said that old weapons material will solve all of the world’s problems. The topic (since you missed it) is how much energy is available in that material. These are the figures that are possible with existing technology that is operating now.

        Oh … and by the way … if you reduce the capacity factor of a plant, you reduce the amount of fuel it consumes. Just like if you drive your car less, you use less gas. The amount of energy that you get from nuclear fuel depends on the burnup, not the capacity factor. So, no, you’re wrong, the amount of energy is not reduced to 10,927 TWh.

        Geez, EL, you can’t even get the basics right. Sometimes I wonder why I even bother to correct you.

        • David says:

          @ Brian

          You are educating me as a lay person. I am thankful for EL’s confusion and the opportunity to correct him and thus give me clear answers for others I dialog with.

        • EL says:

          Brian Mays wrote: “The amount of energy that you get from nuclear fuel depends on the burnup, not the capacity factor. So, no, you’re wrong, the amount of energy is not reduced to 10,927 TWh.”

          Which begs the question … what is the amount of energy (and how far am I off)? Any why not do this calculation for a load following plant. We’re interested in tackling a broader issue, are we not, or just meeting the needs of baseload (and a status quo of 20%)?

          • Brian Mays says:

            I’ll try explaining again using automobiles as an analogy.

            A car will go only so far on a tank of fuel before the fuel is used up. If the car is driven 25% less of the time, that doesn’t mean it will go only 75% as far. The only important number is the miles per gallon that the vehicle is able to achieve. Two identical cars with the same size fuel tank and the same gas mileage will go the same distance on a tank of fuel. It doesn’t matter that one is driven every day and the other is driven only on Tuesdays and Thursdays.

            It is the same for a nuclear plant, except that instead of miles per gallon, the important quantity is gigawatt days per tonne of uranium (GWd/t), which is called the “burnup.” Whether the plant is ramped down (or even closed on some weekends as is done in France) to do load following is not important.

            I will note that how a reactor is run might have a small effect on the amount of burnup that the fuel is able to reach; however this is inconsequential. Besides, I chose a rather conservative burnup of only 45 GWd/t. In France, 50 GWd/t is the norm, and these days, US reactors are achieving 60 GWd/t, which should be standard for any new reactors that are built (e.g., the AP-1000 specs claim 65 GWd/t).

            With advanced fuel concepts, it should be possible to achieve double this number or more in light-water reactors; although these fuel designs will need to use a higher enrichment than is used today. If working from natural uranium, this involves more enrichment and more cost, but if one is down-blending HEU, this simply means that less depleted uranium is needed to make the fuel. The task becomes easier.

            Other reactor designs are capable of very high burnups as well, as Rod has written about here.

            This is what is capable before I start talking about the energy that can be obtained from recycling the fuel after it has been through the reactor. Most of the energy still remains in the fuel and is available for use. This is not science fiction. The French recycle their fuel today and have been doing it for years. They get somewhere between 17% to 20% of their nuclear-generated electricity from recycled material. I didn’t include the electricity that could be generated from a French-style MOX program, nor did I include the electricity that will be generated from the US’s MOX program to burn the plutonium from weapons, which is underway now.

            The numbers that I gave above were very conservatively on the low end. They represent the minimum amount of electricity that could be obtained from this material, using old technology, not even proven technology that is currently in use today.

          • Cyril R. says:

            Using a modern LWR running on weapons grade material downgrades with depleted uranium, the consumption is roughly 0.1 ton weapons grade material per TWh.

            For a load following nuclear fleet, it is the same 0.1 ton weapons grade material per TWh. I used to think that such a fleet would use more fuel, with throttling steam turbines being inefficient… but that’s not how it works in reality. In reality, the french selectively throttle down and shut down some plants, the rest actually runs full bore much of the time.

          • Joel Riddle says:

            Brian and Cyril,

            As a further clarification, I’d just like to point out that if a substantial portion of load following were acheived via steam bypass to the condenser that the burnup (GWd/t) figure would go down.

      • Brian Mays says:

        EL – Here’s another hint for the future. Don’t compare energy in the form of electricity to primary energy, unless you want to demonstrate that you really don’t have the first clue.

        Total primary energy is the raw energy output that is provided by the source — in the form of heat for geothermal, nuclear, and fossil fuels. Some of this thermal energy is used directly as heat, but because of the basic laws of thermodynamics, not all of this energy can be converted to electricity.

        Thus, the primary energy generated by the nuclear fuel from weapons-grade uranium is about three times the amount that I listed. That is, you have to back out the 33% thermal efficiency factor that I applied. Thus, in terms of primary energy, a burnup of 45 GWd/t yields 147 quads or 3700 Mtoe in primary energy. (A quad is 1E15 BTU’s; Mtoe stands for “million tonnes of oil equivalent.”)

        The reference that you cite gives total primary energy consumption as only 98 quads in 2011 and 104 quads in 2035, and these figures are for the US, not the world.

        Much of what you have written is based on bad math and a severe lack of understanding of how energy is used. It’s no wonder that the comments you write here are so confused. You really can’t even get the basics right, and having to explain the basics and correct your mistakes is becoming tiresome.

        • Cyril R. says:

          Fully agree Brian. It’s why we must use a bottom-up approach if we’re going to assume the world is to be powered by nuclear. A lot of things will be much more efficient. Using nuclear electricity in heat pumps and electric vehicles gets us a factor of 4 to 6 improvement over using natural gas in heaters and gasoline in cars.

          EL is making very unfair comparisons. EL is conflating primary energy with an electricity powered world, making nuclear look bad. For some reason he doesn’t run the numbers on any alternative, such as renewables, with a similarly pessimistic data set. How much land, materials, energy storage materials, do we need for wind and solar?

          Here’s one example of a pessimistic (high demand) analysis for a giant energy storage scheme.

          http://physics.ucsd.edu/do-the-math/2011/08/nation-sized-battery/

          Conclusion, simply not feasible by orders of magnitude.

          Conclusion, no batteries, but natural gas and coal to burn as “backup” (absurd understatement) to a wind and solar scheme.

          At the high demand scenario that EL is working on, even a 20% fossil fuel component becomes unacceptable. We are currently emitting 31 billion tonnes of CO2. We need to get under 5 billion tonnes/year ASAP. It is clear that unreliables won’t cut the mustard, even more so with the high demand numbers that renewables enthusasts such as EL like to use against nuclear power.

          • EL says:

            Here’s one example of a pessimistic (high demand) analysis for a giant energy storage scheme.

            http://physics.ucsd.edu/do-the-math/2011/08/nation-sized-battery/

            Nobody is using (or proposing to use) energy storage in this way. The study is complete science fiction. 12 hours storage is enough (and up to a certain percentage of peak generation). Seasonal variability is best handled with adequate resource planning.

            In a world of practical problem solving and viable political outlooks (on local or international basis), if the option is higher fossil fuel mix, or 20% (with a balanced of feasible, low cost, reliable, easy to build, easy to finance, and low-carbon generation alternatives), I’ll take the later in a heartbeat. And some of share of fossil fuels will be biofuels that can be harvested on a sustainable (and low net carbon) basis.

          • Rod Adams says:

            @EL

            If there was a reliable, low cost, easy to build, easy to finance low carbon power source, it would be a winner.

            The only tech with any hope of meeting that description is a fission power plant – after a lot of effort in learning and teaching.

          • Cyril R. says:

            Nobody is using (or proposing to use) energy storage in this way. The study is complete science fiction.

            Good, EL is finally admitting that wind and solar aren’t up to the job. That’s a good start. EL may be in the process of turning over a new leaf.

            Seasonal variability is best handled with adequate resource planning.

            That’s a euphemism for burning lots and lots of fossil fuels. Just be more honest about it rather than putting lipstick on the pig.

            In a world of practical problem solving and viable political outlooks (on local or international basis), if the option is higher fossil fuel mix, or 20% (with a balanced of feasible, low cost, reliable, easy to build, easy to finance, and low-carbon generation alternatives), I’ll take the later in a heartbeat.

            In a world of practical problem solving, not solving a problem 80% is not solving a problem well at all.

            As for reliable and low cost, solar and wind are neither, so your own criteria are biting back at you before you have even finished your sentence.

            EL would be happy to know, that we do have an easy, reliable, 80% solution. Proven by an entire country for decades, as opposed to academic papers. EL would be happy to know also, that France gets much of the other 20% from reliable clean hydroelctric dams. It is a good example of a 90% solution.

            And some of share of fossil fuels will be biofuels that can be harvested on a sustainable (and low net carbon) basis.

            Very little of it will be; this is more of the percent talk from EL.

            However it is clear that EL is in the admittance phase of how useless wind and solar are. That’s good. It reminds me of myself 10 years ago.

          • EL says:

            Cyril R. wrote: “Good, EL is finally admitting that wind and solar aren’t up to the job. That’s a good start.”

            This in no way follows from what I said. Nobody is proposing to use energy storage in the way suggested in the article. Taking an idea that nobody is doing or proposing (or a model that nobody is working on) and saying it can’t be done doesn’t show anything. It shows the impossible would be very impractical indeed (didn’t we know that already)?

            You think we aren’t going to be using fossil fuels in the future? Why is the defense of nuclear a “reductio ad absurdum” argument that fossil fuels must be reduced to zero? You don’t think it is enough to reduce fossil fuel production to levels that meet scientifically informed carbon emission targets?

          • Cyril R. says:

            EL wrote:

            You think we aren’t going to be using fossil fuels in the future? Why is the defense of nuclear a “reductio ad absurdum” argument that fossil fuels must be reduced to zero? You don’t think it is enough to reduce fossil fuel production to levels that meet scientifically informed carbon emission targets?

            The scientifically informed carbon emissions level to be achieved is under 5 billion tonnes CO2/year. Today we are at 31 billion tonnes CO2/year. Economic and population growth puts it around 50 billion tonnes/year.

            So we are talking about a 90% reduction.

            That’s such a deep reduction, the best – and most honest way – to think of it, is:

            NO MORE FOSSIL FUELS.

            Zero. Zulch. Nada. Arguing over that 10% as the base argument in favor of unreliables that can’t power the other 90%, is dishonest propaganda from EL.

  8. James Greenidge says:

    To make such sensible proposals doable you first need clout. Do we really know of any list of “nuclear literate” Congressmen out there?

    James Greenidge
    Queens NY

  9. Jason C says:

    Rod, the “Do the Math” speaking tour is actually now over but 350.org has launched a new campaign called “Go Fossil Free” http://gofossilfree.org/

    Apparently they are trying to get people to divest from fossil fuel companies, which in my opinion will have zero effect.

  10. Engineer-Poet says:

    Blue-skying here:

    Blend the HEU as oxide at 2.5% with the balance ThO2 (or as clad metal fuel, a la Lightbridge).  If the resulting fuel has a high enough breeding ratio to achieve a 50,000 MW-d/t burnup, from 1550 tons HEU I calculate:

    1440 t HEU / 0.025 = 57,600 tons fuel

    57,600 t fuel * 50,000 MW-d/t = 2.88 billion MW-d = 69100 TWh(th)

    69100 TWh * 0.3 = 20,700 TWh(e)

    That’s about 5 years of total US electric consumption, or 25 years of US nuclear generation.  On top of that, the spent fuel could have its remnant uranium (presumably majority U-233) “mined” to make more fuel, or held for use in Gen IV reactors such as LFTRs.  (A third possibility is to burn the LWR fuel down in HWRs, and use the excess neutrons to breed Th to U-233 to top up the net loss in the LWRs.)

    2.5% is my WAG of the U-235 enrichment needed to work in an LWR without burnable poisons.  U-233 would be quite a bit less due to its higher neutron yield per capture.

    • Cyril R. says:

      50 GWd/tU is very tough with LWR on just 2.3% fissile U235. Thorium’s slightly more absorptive than U-238 in LWR neutron spectra, and LWRs that want to reach 50 GWd/tU use a lot more than 2.5% core average enrichment.

      As a rough rule of thumb, the best you can do with LWRs is about 12-14 GWd/tU per % U235.

      Without burnable poison it would be higher but it is very difficult to do this safely. You really want something reliable like gadolinia or other high worth integral fuel poison, to offset the many dollars of excess reactivity for a fresh moderate burn solid fuel LWR core.

      • Engineer-Poet says:

        The breeding ratio of even a LWR core full of thorium will be close to unity (Shippingport exceeded unity).  Burnable poisons manage the change in reactivity as fissionables are depleted, but what if they don’t deplete significantly?  If the initial breeding ratio is greater than unity, you need just enough U-235 to get a chain reaction started.  I don’t know what this is, but given the final fissionable concentration of SNF (~1.0% U-235, 0.8% Pu) I suspect that 2.5% is in the ballpark.  Minimizing the U-235 load would maximize the energy production of the re-purposed HEU.

        The goal would to have a total burnup several times the initial fraction of U-235.

        • Cyril R. says:

          Yes, a high conversion ratio can mean less reactivity swing, but there is still a significant swing from initial isotope change (especially since U233 is much more reactive fuel than TRUs in thermal spectra) plus the fission products, most notably xenon. Especially for high burnup fuel, the other fission products become important poisons as well.

          In a molten fuel reactor, new fuel can be added continuously and xenon stripped continuously, so no burnable poison is needed even for very high burnups.

          • Engineer-Poet says:

            And when we get MSRs qualified and in mass production, that will happen.

            In the mean time, we’ve got a CO2 problem to handle and weapons-grade material to dispose of.

        • John ONeill says:

          how bad a poison is protactinium, compared to xenon and samarium in standard fuel LWR?

          • Engineer-Poet says:

            Pa-233 has a 27 day half-life and a decay energy of 571 keV, so it’s quite hot.  A thorium cycle burning a ton per year would have an inventory of about 75 kg, which is a hell of a lot if it got loose.  On the other hand, a 27-day half life means it essentially vanishes in a year.

            Protactinium forms oxides, so I suspect that a solid-fuel thorium reactor would have low solubility of any elemental Pa in an accident.

          • Engineer-Poet says:

            Oh, you mean a neutron poison.  Look at the capture cross-section.

          • Cyril R. says:

            It’s pretty bad for a high power density reactor. The half life of Pa233 is such that the power density is very important. The higher the power density the higher the neutron flux, the higher the losses to Pa233.

            The losses are very low in a 10 kWt/liter core. This is about the power density of a DMSR. (ORNL’s DMSR had 5 kWt/liter of core but most of us are assuming higher power density to reduce vessel size).

            But PWRs have around 100 kWt/liter. BWRs are around 50 kWt/liter, so are likely more suited to the thorium cycle than PWRs.

            PWRs can just about breakeven on breeding, as proven by the Shippingport final reactor core. And PWRs aren’t efficient reactors – they have all the fission products accumulating in the rods, as well as a high loss to hydrogen. So we can infer that the loss is not prohibitive even in a PWR.

            As for the radioactivity of Pa233, it’s serious. ORNL’s reactor had about 5000 kWt worth of Pa233 decay, and it stays that high for days. It’s actually enough to be a design consideration in the decay heat removal systems.

          • Engineer-Poet says:

            Say, Cyril, as long as you’re watching this, what’s the power density of a CANDU core?

          • Cyril R. says:

            what’s the power density of a CANDU core?

            It’s around 11 kWt/liter of calandria.

            Inside the actual pressure tube, ie just the active fuel core, the power density is actually higher than a BWR. Power per kg of uranium is 20 kWt/kg U for BWR, 40 for PWR, and around 24 kWt/kg U for CANDU. But the CANDU has a tight lattice fuel element, cramming more uranium in per liter, so the power density per liter of active core approaches the PWRs 100 kWt/liter (I don’t have an exact figure for this one).

            CANDUs are quite good with thorium, because in the well thermalized spectrum, losses to Pa are lower.

          • Engineer-Poet says:

            Thanks!  That was my impression too, but I hadn’t been able to find figures to confirm it.

            Since there’s such resistance to moving SNF in the USA, this suggests a way forward over the next 2-3 decades:
            1.  Build CANDUs on existing LWR sites.
            2.  Recycle the LWR SNF as DUPIC fuel elements.
            3.  Initially fuel the CANDUs with a mix of DUPIC and thorium rods.
            4.  When the CANDUs have enough U-233 to run self-sustaining, use the DUPIC plants to re-compact burnt Th/U fuel pellets for re-use until the poison loads are too high.  No reprocessing or enrichment.
            5.  Excess U-233 may go to help establish new reactors on other sites.  The easiest way to move it would be as intact fuel elements.  These rods would only need the minimum U-233 to achieve a chain reaction in a CANDU, so they would probably have tiny burnups to make transport easier.  I can see “blanket” rods being used for this.

            Nothing needs to leave the site except fuel required for starting a new complex.  An expansion of dry cask storage would suffice for holding the CANDU effluent, and spent Th/U rods would be ripe for processing into LFTR fuel at a later date.  The existing LWR sites remain active even after the LWRs reach end-of-life.  It looks like a quadruple win to me.

  11. Bruce Behrhorst says:

    Of fissile isotopes: U233,U235,U239,U241 all can be put to use in reactor core. Rod won the argument so I won’t go there.

    For the sake of brevity I’ll just highlight BRUCE nuclear power plant park, the largest nuclear facility in the world. The side feed pressure HWR commissioned in 1977 runs 8 reactor units.
    4 x 750 MW (A 1-4) -&- 4 x 817 MW (B 1-4)

    For an installed capacity of:
    6,232 MW
    Annual generation
    6,232 MW
    Net generation
    7,276 MW

    Electrical output in 2008: 35.26 TWh

    Bruce Power supplied about a quarter of Ontario’s energy in 2011.
    That’s one out of every four light bulbs, computers, and medical
    devices in the province.
    Global Electricity Generation in 2011
    (www.cna.ca)
    Energy source percentages:
    (www.ieso.ca)
    -Gas
    14.7%
    -Hydro
    22.2%
    -Coal
    2.7%
    -Nuclear
    56.9%
    -Bruce Power
    24.8%
    (42% of nuclear)
    -Other
    0.8%
    -Wind
    2.6%

    Bruce NPP is a monster facility they named the NPP park after me. *joke liberty
    http://www.brucepower.com/wp-content/uploads/2011/04/GuideToBrucePower3.pdf

    There might be future projects with spent fuel storage and recycling, spent fuel re-processing facilities on Indian land staffed by aboriginal tribes providing employment opportunity.

    • Cyril R. says:

      Thanks for the information. I really like these big nuclear power facilities. The bigger they are the fewer we’ll need, that should help with public acceptance. The energy problem is big, so we have to think big.

      Bruce Allmighty.