Exploded view of Lightbridge fuel assembly.

48 Comments

  1. SWEET! I was the one that got Lightbridge invited to speak at that Idaho National Lab meeting. INL was kept requesting me to attend this meeting on Fuel Safety. I told them I would only come of they invited Lightbridge to speak. INL invited them, and Lightbridge agreed to come & talk. I also convinced INL to give Lightbridge a tour of the facilities, as I saw that they were exactly what Lightbridge needed to get qualified.

    Everyone can have an impact. Never be afraid to speak up for what is right. I also ensured that DOE knew in the open meeting that Lightbridge was the only accident tolerant fuel that was lower cost and higher performance of any of the public ATF s, AND that these two things are absolute criteria for accident fuels to be economically viable to utilities.

  2. By the way, ATF no longer stands for “Accident Tolerant Fuel.” It officially stands for something else … which I cannot remember at the moment.

  3. It’s been a long time since my last reactor theory course, but a statement above has me confused. If “average temperature that is several hundred degrees lower than conventional fuel”, won’t this have a dramatic effect on the Doppler coefficient during operation?
    Also, the industry has gone thru a lot of struggles to resolve Pellet Clad Interaction (PCI) in the last few decades. It’s harder than people thought to make a round pellet that won’t fracture at some point over 6 years in the core. If the LightBrigde fuel is cruciform shape, how will they avoid PCI with these complex shapes?

    1. The fuel is metallic and therefore ductile, not ceramic.  It’s welded to the cladding.  (hoping I can kill the italics here)

    2. @cpragman

      Lightbridge fuel is a metallic alloy of Uranium and zirconium clad with a uranium-free layer of zirconium. It is co-extruded.

      There are no pellets that can fracture. Sometimes the easiest solution to material fabrication problems is to avoid them altogether.

      1. Rod,
        Where did you learn the following:

        “Severe accident and design basis testing will be conducted in Idaho National Laboratory’s TREAT facility.”

        I know LTBR recently presented in Idaho but I’ve only read that they are testing in the Halden Reactor in Norway. Are they also or alternatively planning on testing in Idaho?

  4. I find nuclear fuel technology to be no less interesting and important than nuclear reactor technology. It’d be fascinating to see a metallic fuel in a commercial reactor.

  5. Did I hear correctly that NuScale was considering, or planning on, using this fuel? If they did, it would make fuel melting in that small reactor even less credible, and could reduce the (already tiny) potential release even further.

    One question concerning this fuel. How good is this uranium-zirconium alloy at confining various isotopes, as compared with UO2 ceramic?

    We’ve come to understand that in meltdown scenarios, “volatile” isotopes such as cesium and iodine are the only ones that are released in significant quantities. The reason is that other isotopes (e.g., strontium, the actinides, etc..) are very effectively confined by the UO2 ceramic material. Will this metallic material perform as well?

    I understand that the much lower peak fuel temperatures will act to greatly reduce release fractions, but we also have to account for the different chemical/physical composition.

    1. How would this type of fuel handle a lost of power( Fukushima) type scenario or a loss of coolant (pipe break) type scenario?

      Also, Lightbridge say that using their fuel will save operators between $33M-$71M pa for a 1.1GW an existing PWR. (no BWRs?)

      Just how big a deal is this given the gloomy economics facing nuclear power in the US?

      1. The Lightbridge fuel type would handle most transients better. It would generally be worse in a long term loss of coolant/cooling type situation, because of the lower melting point and increased amount of zirconium (meaning more hydrogen generation potential). Though that’s not really a valid criticism; such scenarios depend on the emergency cooling system (e.g. having a passive cooling system or active cooling system with hardened power supply) rather than on the fuel for a succesful outcome. Power reactor cores need cooling after shutdown because of decay heat, this is the case regardless of fuel form…

    2. ‘To date Lightbridge has simulated a large break loss of coolant accident for a VVER-1000 with our metallic fuel. The peak fuel temperature observed for the metallic fuel was less than 500 degrees Celsius, well below the temperature required to initiate steam interactions with the zirconium cladding (i.e., above 900 degrees Celsius). The high thermal conductivity of the metallic fuel results in the fuel temperature decreasing to the temperature of the coolant water in less than 60 seconds with little to no increase during the blowdown phase of the accident. The same accident was modeled with conventional uranium dioxide fuel and showed a near instantaneous cladding temperature rise to above 1000 degrees Celsius. The fuel and cladding temperature continued to rise during the blowdown phase of the accident and did not reach a safe, stable temperature until nearly 8 minutes after the accident began. ‘
      Both conventional oxide fuel and Lightbridge metal fuel have the same zircalloy cladding, and that will start to react exothermically with the water coolant at around 900 C, further increasing temperatures. By that stage, pressures will be so high that the pressure vessel has to vent or rupture, and some outgassing of cesium and iodine is inevitable.

    3. NPPs can (should be) designed to safely shutdown/cooldown on loss of all electrical power. As part of the TMI-1 restart a natural circulation verification test was performed, [Ref. http://www.nrc.gov/docs/ml0037/ML003763919.pdf for the needed amendment.] This test was run during startup and verified computer models and the previous 1/4 scale test that were brought into doubt by the UCS.
      A design with turbine feed pump(s) to supply the water (which TMI has) to feed the SG to make the steam to feed the SG. Very few other auxiliary systems would be needed [Instrument Air, Safety Related Instrument Power systems, and other vital system needed on loss of all electrical power] which could also be driven by small turbines using steam and thus helping cool the Reactor. A dry pipe which could be feed at some distance by a fire hose/truck could feed any on sight storage pools. And part of the problem with the cooling of spent fuel is that NPPs have become de facto storage sites. They were NEVER designed in the begining to store 40 – 60 years of fuel. If used as designed there would be less than 1/4 the fuel stored in these spent fuel pools. after Yucca Mt got delayed it seemed like ever ten years a license amendment was written to increase the amount of fuel stored in these pools. And that is why there was a problem at Fukushima.
      Search the internet and look at the license amendments for increasing the spent fuel pool loading. Makes you wonder if the UCS is really concerned with safety or if their idea of safe is permanently shutdown.

        1. Which uses the UCS and Ed Lyman (bitterly anti-nuclear) as their major source, and therein we find a hint as to WHY the UCS is after these “strengthened” regulations:

          the problem is simply that they drive up costs and are thus unwanted by those in the industry and associated with it.

          Ratcheting costs up has been one of the perennial strategies of the anti-nuclear activists practically since day 1.

          The idea of a 50-mile disaster planning zone for spent fuel is ridiculous.  The only part of SNF which can burn is the cladding, and if the pool has boiled dry there would be only a bit of steam for it to react with.  Burning in air would be limited by convection and quickly choke the flow of air with tumbled ceramic fuel pellets and possibly melted separators.  Last, after a few weeks there would be no I-131 left and the relatively volatile cesium is a heavy element that doesn’t form vapors at ambient temperature.  A one-mile disaster radius may be excessive.

          But let’s assume the problem must be taken SERIOUSLY.  Per this guy (whose only cite for cost is a #FakeNews site known for its propaganda) it wouldn’t be all that much:

          It costs about 1 million USD for each cask and another half million USD to load each one with fuel. [7] The concrete pad for casks to sit on costs another 1 million USD. A rough estimated cost to move all of the fuel in the United States that has cooled in pools for at least five years could cost 7 billion USD.

          That works out to 2800 casks.  I think we can safely assume that the concrete pad for a bulk-storage site would be much cheaper due to economy of scale in NRC certification, so maybe $100k/cask for a site holding 10k casks.  That would total $4.2 billion for the loaded casks and $1 billion for the pad, total $5.2 billion with plenty of room for expansion.

          I’m not sure what those casks weigh, but I’d bet that you could fit most or all of the fuel at a nuclear plant in casks on one barge.  Figure transport by barge to Texas or some Mississippi port and then overland to e.g. New Mexico by rail at $10 million per reactor, times 104 reactors, $1.04 billion.  Total $6.24 billion.

          Nuclear utilities have paid more than $30 billion for waste disposal thus far.  We could have this job done in 3 years; there’s more than enough money.

          Guess who’d be blocking the ports and railways to prevent it from happening?  Ed Lyman and the UCS.

          1. 7 billion is overpriced for simple casks. Yet in a more important way, it is pretty cheap. US nuclear power output is over 90 GWe average.

            7 billion in solar PV installations would barely get 1 GWe average output. And no cost included for managing the e-waste of solar panels. Some solar companies are claiming they will take responsibility for the e-waste, but little financial commitment is made to it (unlike in the nuclear industry where a large sum of money has been set aside).

            Even in the future will dramatic cost reductions in solar, 7 billion would barely get 2 GWe of average output.

      1. @Rich: The spent fuel at Fukushima was not a problem (if that’s what you meant).

        The city-smashing tsunami that wrecked infrastructure all along that coast and killed the electrical supply at Fukushima Daiichi caused the reactors to melt down – not the spent fuel, which stayed passively safe in its pools.

        Sure there was a lot of hoopla about spent fuel. The apocalyptic talk was flat-out wrong, as subsequent events and investigations amply demonstrated.

        One of the key lessons learned that should be learned from Fukushima is how not to do an evacuation.

  6. According to LTBR and several studies the fuel runs almost 1000 F cooler. I am not a nuclear expert so can’t answer some of the more technical question but have been following them a long time. I called into the recent earnings call and asked Seth about the persistent milestone delays which are maddening to us investors who are tired of ‘hanging in there’.

    However I was pleased Seth, the CEO, acknowledged the Areva JV had been delayed because of its expansion to a more lucrative arrangement. Missing deadlines and pushing back the goal posts in addition to negative investor sentiment surrounding nuclear energy has caused much of the decline in their price. I never take every word CEOs say literally since they are protected by Forward looking statement clauses but I did get the sense Lightbridge is very close to the joint venture which would then lead the way to testing in Norway and usage in US Utilities and international Nuclear utilities. There is a lot of new and exciting nuclear reactors under development like TerraPower but those are not coming online soon. Improving the safety and efficiency of existing reactors could indeed be a huge business for years to come. Their fuel could be used in a SMR Nuscale reactor but up to now that happening is only speculation. But this potential is the source of Areva’s interest and the core of the investment thesis.

    https://www.technologyreview.com/s/601121/this-new-fuel-could-make-nuclear-power-safer-and-cheaper/

  7. A very responsive company. I remember when trying to interest them in the Vermont Yankee plant a senior executive(s) answered me right away. Such efficiency and politeness is unknown in the Vermont political community (where most politicians don’t bother to answer mail or reply promptly and directly) but shows a corporate culture of – dare I use the word – “care”. Thanks Rod for your continuing contributions..

  8. A very exciting development that could increase output and competitiveness of a large number of plants. As others have pointed out, the easier flow through the core would be particularly beneficial for the NuScale design, as it relies on natural circulation at full power.

    Is it possible to have traditional and lightbridge fuel side by side in the same reactor? Or would the LB FE scavenge too much flow from its neighbours?
    If not, how important is the need of an extra fresh fuel load for the economics of the conversion of an old plant?

    1. I’m particularly curious about the possibilities of a U-Th-Zr alloy fuel.

      Using thorium as a breedable, rather than a burnable, poison appears to allow a core lifetime of roughly 4 years at full power in a NuScale-sized plant, if we take the example of the LWBE at Shippingport.  A 4-year core lifetime doubles the refueling interval of a NuScale and should have beneficial effects on the economics.  This should be true even if the fuel is not reprocessed.

      If the fuel is reprocessed, the U-232 decay chain should make sufficiently aged reprocessed fuel effectively impossible to steal.  It would have to be shipped to the reactor site in a dry cask, just like the fuel that’s removed for reprocessing.  It makes nuclear weapons proliferation impossible.

      A pure-Th neutron shield and breeding blanket around the active core would have a far lower heat output than the core proper, so it could have a much greater fraction of area occupied by metal rather than passages for cooling water.

      1. Keep in mind though that thorium’s higher absorption cross section requires a higher fissile starting load. This, combined with the need for higher enrichment (since there is less uranium in the U-Th fuel), would lead to increased fuel cycle cost. That has to be weighed against the neutronic gains of the thorium cycle. Without fuel processing it may not look so good, at least economically.

        1. Thorium has nothing on Gd-157 for sucking up neutrons.  IIUC that’s the most commonly used burnable poison in LWR fuels.  Since thorium levels the reactivity curve by breeding it up instead of removing its absorption as it transmutes, the initial (total) fissile concentration ought to be lower.  That might be cheaper, as well as greatly improving the neutron economy.

          Reprocessing doesn’t have to be attractive now to be a worthwhile option.  When you have a plant with a lifespan of 60 years or more, the first load of SNF out of it has lost about 3/4 of its Cs-137 and Sr-90 by the time it’s shut down.  The greatly reduced heat load and gamma emissions might make it an attractive option for reprocessing to fuel the next generation plant down the road.

          I imagine people working for 3 generations to build inventory and then being able to “coast” at mere replacement levels as the previous work pays dividends for centuries.  Truly a civilizational effort.

          1. It’s true, a thorium fuel cycle typically has lower burnup reactivity swing. However, it is certainly not zero. For one thing, U-233 is quite reactive, compared to U-235. So a U-235 started Th core will have reactivity swing as U-233 is bred. Similar to plutonium breeding into the fuel but different strength and dyamics. Some reserve reactivity will be needed – if not burnable poison then control rod action. In addition there is xenon to be concerned about. Likely some burnable poison, in addition to control rod action, will be required.

            That is of course if you use a solid fuel – if the fuel is liquid, xenon worth is much reduced, and makeup fuel can be added in a simple fashion, online without shutdown or complex refueling machinery.

            This is what we’re working on with Terrestrial Energy – though our focus is on low enriched uranium fuel for the first generation IMSR. Still thorium holds many potential advantages that get pretty good with some re-use and re-cycle of fuel. Thorium may be hard to ignore for the next generation IMSR…

          2. U-233 is quite reactive, compared to U-235. So a U-235 started Th core will have reactivity swing as U-233 is bred.

            But which direction, and how fast?

            Calculating things like the accumulated poisoning effect of e.g. yttrium versus the greater reactivity of bred U-233 vs. original U-235 (and the flux-related net cross-section of Pa-233!) is way beyond my pay grade.  I post my speculations mostly in hopes that someone who knows (and I’m sure the folks who did the LWBE knew) has a pointer to an accessible version of that info.

          3. Hi E-P,

            Most of the date on Shippingport’s thorium core is available online. A good one is here, it has much good stuff in it from the times when people cared about this stuff:

            https://www.osti.gov/scitech/servlets/purl/5914091-SAaveY/ShippingportoperationswiththeLightWaterBreederReactorcore.(LWBRDevelopmentProgram).pdf

            It gives measured 14.9 mk (1.49%) xenon and 20.5 mk (2.05%) Pa reactivity worth.

            These are quite substantial worths, needing control rods of some sort, to avoid excessive thermal cycles and temperatures. For PWR which has limited thermal margins, even 1% reactivity is a huge amount and far too much to deal with by the reactivity coefficient alone, at least for normal operations purposes. Liquid fuel can reduce the Xe worth quite drastically, but the Pa swing is not affected much. It’s a rather peculiar issue with the thorium fuel cycle that few people appreciate.

          4. Thanks a million, Cyril!  I was sure that was out there, but none of my searches had ever turned it up.  That required a brain, not someone’s Pagerank algorithm.

            Now let’s see if I have the background knowledge to make heads or tails of it.

    2. @RRMeyer

      Yes, it is possible to have some elements with Lightbridge fuel and others with conventional fuel. Part of the strategy for licensing described in this piece talks about putting Lightbridge fuel in non limiting locations in operating reactor plants.

      I do not know the technical details, but I suspect there is some kind of flow limiting provision to equalize the coolant flow through the varying elements.

  9. Rod & other Nuclear Energy experts:

    Am I correct in thinking that, if this fuel works out and provides the additional safety benefits claimed, that, while the fuel is currently being targetted/marketed as being for already existing nuclear plants, that conceivably, and likely, it could also be targeted as being the fuel that new, reduced complexity (because of lower safety requirements because of the inherent safety of not being physically able to generate H2 gas – if that ends up indeed being true), and therefore significantly lower costs to site and build nuclear plants designed specifically for this fuel?

    It seems to me that if this fuel has the advantages claimed, that not only could you design and construct simpler plants that would be cheaper to construct, but also, costs associated with regulatory requirements such as evacuation zones and plans could also be substantially reduced (since hydrogen explosions are the primary mechanism/risk for dispersion of radioactivity outside the plant boundary; I think the other risk is steam-pressure explosions, but designs similar to NuScales, that have passive cooling, could mean that risk of steam explosions becomes close to zero also)?

    The significant breakthrough nuclear power needs is, in the end, much lower cost and time-to-completion for new plants.

    Seems like Lightbridge fuel + passive cooled plants + small modular construction could maybe dramatically reduce costs and time-to-build?

  10. The Westinghouse news can be read both ways. On the downside if they are first to market they could squeeze out whatever niche Lightbridge was hoping for. On the upside it may help drive interest in accident tolerant fuels for which there is room for more than one player. From what I know Areva and Westinghouse are direct competitors so it’d be in their interest to use Lightbridge fuel if it is equal or better. Increased safety may be a shared trait between Lightbridge and Westinghouse but I am not sure if Westinghouse has the same economic benefits that Lightbridge claims it has. I just wonder when if ever this proposed joint venture is going to happen. The price is where it is because of the trend of missed dates and unfulfilled promises hopefully Westinghouse will accelerate some real ACTION.

  11. The Accident Tolerant Fuels plot thickens (from WNN Digest):
    Westinghouse launches radical new fuel
    As part of an international Accident-Tolerant Fuel (ATF) program sponsored by the US Department of Energy (DOE), Westinghouse has launched its EnCore Fuel. It plans to manufacture the first EnCore Fuel test rods in 2018, with lead test assembly insertion of these starting in 2019, with Exelon’s Byron power plant being mentioned in media. The initial EnCore fuel comprises high-density uranium silicide pellets inside zirconium cladding with a thin coating of chromium making it more robust chemically. In the second phase, the uranium silicide fuel pellets will be in silicon carbide cladding with melting point of 2800°C, and these test assemblies could be loaded in a reactor by 2022. The EnCore ATF fuel development has been supported by DOE and partners including General Atomics, several DOE national laboratories, Southern Nuclear Operating Co. and Exelon.

    As part of the same international ATF program, Areva is developing fuel also with a chromium-coated zirconium alloy cladding, but combined with chromia-doped fuel pellets. GE Hitachi is developing a ferritic/martensitic steel alloy cladding (eg Fe-Cr-Al) for conventional UO2 fuel.
    WNN 14/6/17

  12. Did the pleasant surprise become a rude awakening? I had thought they were only going to dilute ” if and only if following one or more significant events.”

    “The rationale for this request in trying to maximize financial flexibility is that we want to do this in advance of what we believe will be the most major milestones in the history of this company, and potential very significant strategic transactions with major entities in our industry this year. And we want to utilize this authorization if and only if following one or more significant events.”

    Is this a blatant broken promise or is there something bullish in the works?

    1. @James Anderson

      I have no specific information on the dilution. From the post: “Grae said that Lightbridge would be making a major announcement related to the JV within a month.” Knowing a bit about finance, it is possible that there was an opportunity to use some cash to ensure a stronger equity position in the JV.

    1. The problems with the nuclear industry are MORE than priced in. Uranium is at decade lows. There are many new reactors coming online, and Lightbridge fuel can help existing reactors overcome some of the safety risks while being more profitable. It also works in new reactors which carry less stigma. Perhaps LTBR fuel would pave a way for existing and new reactors to receive the federal subsidies? I am not worried about the nuclear industry surviving. I am concerned with competition from Westinghouse and other Accident tolerant fuels as well as LTBR actually closing a fuel related deal for the first time in their history.

      1. The post addresses competition from other vendors who chose to participate in the ATF program by making technical choices that were acceptable to the granting reviewers.

        Though Lightbridge has not participated in the U.S. Department of Energy’s accident tolerant fuel program as a grant recipient, DOE and nuclear utility companies have started to realize that its fuel invention might be an even more capable solution than the ones that the program has supported.

        Malone, answering a question posed by a caller about accident tolerant fuel said, “We considered it [participating in the program] early on and were not looked upon favorably by the advisers to DOE at the utilities because of the zirconium in the fuel. They were overreacting to the fact that we have zirconium and zirconium was a problem at Fukushima.”

        But the Energy Department recently invited Lightbridge to participate, along with the Nuclear Energy Institute and the Electric Power Research Institute, in all the events and meetings related to accident tolerant fuel.

        “I spoke at the meeting in Idaho and said that while Lightbridge fuel was once an ugly duckling it is now certainly turning into a swan in the eyes of the community,” joked Malone.

        I know Jim Malone and Seth Grae to be skilled technologists and also know a bit of the background of their fuel design team. I think they made the right choice to remain independent of government rudder orders in their quest for a better fuel design. They were seeking better thermal and hydraulic performance and found accident tolerance as a bonus feature.

  13. This is something related to the Atomic Insights blog in general rather that this post specifically. I am starting something that I think is needed. An ‘Index of Anti-Nuclear Claims’ with rebuttals.

    I was thinking I should give just the most sensible version of a claim, ie: steelman rather than strawman it:
    http://rationalwiki.org/wiki/Straw_man
    but there might be some merit to giving both the silliest version someone has acutally claimed & the most sensible, hardest to rebut, version.

    Please help fill in the blanks in my index & add claims & if possible links to rebutals of the claims.

    So far I don’t have a website to put this on. Any suggestions for how to do this public service cheaply would be appreciated.

    Here is the start I have made on this project

    Introduction:

    The oppostion to nuclear power is an example of this observation:

    “The greater the hatred the less the reason”

    http://markhumphrys.com/laws.html#no.2

    Mark Humphrys only gives examples of groups of humans who are hated for no reason, but his observation applies to other things like hatred of a technology or an idea. Pseudoscientists tend to have intense hatred of the actual science & the people who point out the flaws in the pseudoscience. Creation ‘scientists’ on evolution & real biologists is an obvious example. (Note: This index is in part inspired by “An Index of Creationist Claims” http://www.talkorigins.org/indexcc/ )

    The antivax & anti-GMO crowds also seem to be cases of virulent hatred based on solely lies.

    In the case of nuclear power there are a few claims the opponents use to make their opposition seem reasonable, but which are somewhere between half-truths & lies, generally much closer to the latter.

    Claim 1) Nuclear power is dangerous
    [link to example of where this claim is made]

    The minute grain of truth here is that the chance of injury or death from A nuclear power plant is greater than zero. What makes this for all practical purposes a lie is that every other energy source has a worse safety record.
    http://www.nextbigfuture.com/2016/06/update-of-death-per-terawatt-hour-by.html

    Claim 2) Nuclear power leads to Nuclear Bombs
    [link to example of where this claim is made]
    The closest to truth this comes is that most nuclear power reactors use low enriched uranium ( a few % U235 vs 0.7 % U235 as it is mined) and the same enrichment machinery that makes low enriched uranium can be used in a modified fashion to make bomb grade uranium (90+ % U235). This is the only dual use (power & bomb) technology.

    [ Find something about when various countries got nuclear weapons & when nuclear power]

    It is often stated or implied that the plutonium in used fuel rods can be used for bombs.
    [link to example of claim being made]
    https://web.archive.org/web/20100429092527/http://depletedcranium.com/why-you-cant-build-a-bomb-from-spent-fuel/

    Nuclear power plants can be used to destroy weapons grade material & make electric power at the same time
    https://en.wikipedia.org/wiki/Megatons_to_Megawatts_Program

    Claim 2a) A nuclear reactor can explode like a nuclear bomb
    [link to example of where this claim is made]
    [Find the best debunking of this BS]

    Claim 3) Nuclear waste is an unsolved/unsolvable problem
    [link to example of where this claim is made]

    1. @Jim Baerg

      My plate is pretty full until after the 4th of July, but please make contact with me again about that time. Perhaps it is a project that we can work on together. As you know, I already have a blog with a reasonably broad and engaged audience.

    2. I am starting something that I think is needed. An ‘Index of Anti-Nuclear Claims’ with rebuttals.

      Your thoughts and mine have been going in very similar directions.

      I have the beginnings of such an index already, and if you’d like to collaborate I’d be happy to host the results at The Ergosphere.

      1. Sounds good.
        I would like to see what you have so we can decide how best to combine my start with yours. Have you got it posted anywhere, or do you want to send it to me at jimbaerg@gmail.com ?

        1. It’s posted everywhere… and that’s the problem.  It’s in comments sprinkled across the blogs I frequent, most especially rebuttals to the odious Bas Gresnigt/Bentvels at The Energy Collective.

          However, I do keep a local archive of my posted comments of significance, and that is pretty easy to sift through.

          Mail sent.

      2. I’m also working on something similar, but it will be called (more politically correct and neutral perhaps) the “atomic power – frequently asked questions”.

        Or perhaps “common questions – and uncommon answers”

        : )

  14. Current state of the art lattice physics codes might have trouble with the change in fuel/water ratio as the fuel swells with exposure and displaces water. I read that the lobed cross-section changes area significantly due to swelling.

    1. I just found this page, and was wondering something similar – this is metallic fuel, so what allowance is being made for the fission products? Current fuel designs use ceramic fuel because it includes space in the matrix for the FPs. They even provide space in the plenums for gaseous FPs to accumulate, and they deal with the increase in pressure inside the cladding as a result of FP accumulation. Metallic fuel does not have any space built-in to accomodate FPs, so what is being done about the fuel swelling that will result?

Comments are closed.

Recent Comments from our Readers

  1. Avatar
  2. Avatar
  3. Avatar
  4. Avatar
  5. Avatar

Similar Posts