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    Think you know it all. Delve into this.
    https://www.ornl.gov/sites/default/files/ORNL%20Review%20v26n3-4%201993.pdf #page=26

    This the 1993 report ‘Coal Combustion: Nuclear Resource or Danger?’ by Alex Gabbard, curtesy of Oak Ridge National Lab, Tennessee USA.

    I draw your attention to the plot a couple pages in, showing global release of Uranium and Thorium, according to which by now we ought to be at around *eight thousand metric tons* of U into the atmosphere, due to burning coal.

    Also points out coal makes about 6 MWh/ton, whereas U-235 does about 2000 MWh/ton. Even with particulate filters on the exhaust, “The amount of U-235 alone dispersed by coal combustion is the equivalent of dozens of nuclear reactor fuel loadings”.

    And that’s not to say anything of the mercury, arsenic, lead, chromium and others being dusted down upon our heads and into our childrens’ lungs. I mean forget the radioactivity: These are ‘forever toxins’.

    Anyway, an article further into the file, on the future of nuclear reasearch facilities says: “The challenge for nuclear power is to develop solutions to the twin problems of accident potential and waste disposal.”

    The problem with triso fuel is this:

    Sure, you’ve solved the ‘meltdown’ problem by making it basically impossible for the fuel to melt.

    Better, you’ve banned water from the core: A highly sensible thing to do, because the defining feature of ionizing radition, is that it does radiolysis: it breaks molecules. Especially covalent bonds. Elemental nonreactive, or ultra-stable ionically bonded molecules for coolant need only apply. Also nothing that can boil, expand, and cause a steam-bomb explosion.

    So PBR with triso has full marks for the ‘accident potential’, and this sort of thing is why we should never allow water-*cooled* cores again.

    But what about waste disposal?

    Solid fuelled reactors are literally ‘as dumb as a pile of rocks’, they ‘shit where they eat’.

    So the limiting factor on fuel use is not actually using all the fuel, like you’d expect, but actually more than 80% to even 98% is typically *wasted*, because of the build-up of that ‘shit’.
    Triso by design tries to seal everything inside, including all the reactor poisons which kill the neutron economy, which is why you only get to eat one slice of your cake, before having to throw the entirety of the rest away.

    And *still*, even with that waste: roughtly 1/3 of a thousand times better than coal. And it could be about 50X better: Just by using a reactor that allows the waste to be removed. This is the promise of Liquid Fluoride Fueled reactors (whether or not they breed Thorium – whole other issue: only 0.72040% of natural U is U-235. But if you can use Th-232, then you get to use it all. And there’s typically 4 to 5 times more Th-232 basically anywhere you find natural U).

    The really telling metric, btw, is when you figure out how many tons of earthmoving needs to be done, to mine for the energy. This is a lot harsher on the Uranium, since it’s never found at high concentrations the way coal is. Once you take that into acount, then solid-fuelled, shit-where-they-eat, dumb-as-a-pile-of-rock, steam-bomb reactors come out almost equal with coal. And that’s giving both a ‘free pass’ on waste disposal: For nuclear, that cost gets paid, so it works out as more expensive energy. Even more so, if you’re stupid enough to scale-down those plants. (eg: the Nuscale scam).

    But merely for going liquid-fluoride fueled U, you get a factor of 5-50x *better than that*, whilst still being seriously accident-proof.

    Sure, it can ‘melt down’, but in a liquid-thorium reactor, that’s so not a big deal: They are designed to melt down and auto-safe themselves without the slightest risk of damage to anything, and in such a way as they’d never even wear themselves out doing so. There isn’t even a valve that might fail (look up ‘freeze-plug’).

    Rather than try to ‘banish’ melting and flowing of the fuel from the core, like TRISO does through brute force, they take advantage of it to move the fuel away where it can be safely passively cooled for years without attention.

    And on top of that, no need to ‘play with your food’ like solid fuelled reactors. LFFR’s *do not care* what physical form the fuel is in, before you let it dissolve in the molten salt. No pointless expensive fuel manufacturing required.

    So on the TRISO stuff: Meh.

    China is also building an all-up Liquid Fluoride Thorium Breeder reactor. They’re deep in the guts of the predictable-as-hell schedule overrun you always get with a FOAK, but that one is the one to keep an eye in the news for. They’re a few years yet away from commercial operation, but I have no doubt they’re pulling out all the stops to get there.

    Only question, is if Copenhagen Atomics gets there first? Those guys are doing one also, and their plan is to take full advantage of the LFTR design, to make even smaller modular reactors which can be mass-manufactured and shipped almost-ready-to-run. They intend not only beating those two problems – safety and waste disposal, but also doing so whilst making LFTR’s the *cheapest* energy on the earth, and that’s including coal.

    Given the numbers and ratios above, I hope you can see why the physics say this is easily possible, even given additional costs of recycling both waste and used reactors.

    response 1
    >why is it that it was not the US, Germany or South Africa to first commercialize PBRs, but relative newcomer China?

    Because the Chinese government really doesn’t care if the thing goes belly up and a couple million people die or get sick.

    When Areva/EDF was building the new EPR fission plant in Finland, they also started building a copy of the reactor in China. The Finns noted several design flaws, omissions and errors that didn’t meet the safety standards and requirements, resulting in Siemens pulling out of the deal and numerous rounds of revisions and re-designing parts of the whole plant with years and years of delay and billions of dollars in cost-overruns.

    The Chinese just went with their original EPR – “no problems here” – and the plant was built on schedule as it were.

    response #2 (winner)
    “Because the Chinese government really doesn’t care if the thing goes belly up and a couple million people die or get sick.”

    Yet a few years ago China banned import of scrap plastic for recycling because people were getting sick. From I think 1960s until a few years ago, China imported many of the plastic types that USA and Canada (and few more other countries) deemed not profitable enough to sort properly and clean residue before shredding them and sold as recycled pellets.

    Apparently a large number of Chinese workers were getting sick off toxic residue found on waste plastic, and since China’s heath care are government funded, China choose to ban import to stop more of their people from getting sicker and costing more in medical expenses.

    Nuclear accident will create a whole lot more problem than what imported toxic residue created. I would think China government would prefer not to have any accident at all, and will be holding every workers and their families’ head under guillotine should something go wrong.

    #3 The NRC just authorized the construction of a new reactor down at ORNL by Kairos Power, to test pebble bed fuel. 20 years ago, the chief of fuels in NRR (a real flaming asshole, I understand ) told the people who wanted to build pebble bed reactors that they needed to get real data about the fuel performance before anyone would accept their calculations. Real data about fuel performance at design rated temperatures, at design rated burnups, in the coolant that they wanted to license.

    Now, it appears that the newest proponents of pebble bed fuel have decided to build an actual test reactor to see if the fuel performs as they expect.

    The Germans could not produce consistent fuel pebbles unless one particular person was operating the machine that made them. And they had problems with the data from the fuel that they did irradiate because by its very nature, you never know where the pebbles are going to land in the reactor vessel, or what the power level is going to be at that location, or how the pebbles are going to move thru the pile and accumulate fission products or fluence. They had no data for fuel at its rated design burnup.

    And the Germans admitted that it was hard to figure out which balls burned in which way. They had tagging wires in the balls to identify them, and give them some idea of the temperatures the balls experienced when they came out – the balls are recirculated constantly during operation. Some balls experienced higher temperature than was predicted. Some experienced higher exposure than was predicted. Some balls NEVER CAME OUT OF THE REACTOR DURING ITS OPERATING HISTORY.

    How are these people going to come up with fuel performance models for fuel that is burned beyond its rated/tested/modeled experience?

    We have no idea what the Chinese are doing, or what sort of qualification program they have for their fuel. If they have an accident, we will probably find out about it from radiation monitors in Korea or Japan, at their nuclear plants.

    #4 (funny)
    IIRC the Swiss have a melted down, gas cooled, weapons grade production, reactor inside a hollowed-out mountain. Right where they left it.

    Only the Brits thought a convection flow, open _air_ cooled, weapons grade production reactor was good idea. Anybody experienced with English cars could have told you how that was going to end.
    2 years, 5 months ago