[HN Gopher] Application submitted for US molten salt research re...
___________________________________________________________________
Application submitted for US molten salt research reactor
Author : PaulHoule
Score : 309 points
Date : 2022-08-22 16:18 UTC (6 hours ago)
(HTM) web link (www.world-nuclear-news.org)
(TXT) w3m dump (www.world-nuclear-news.org)
| benreesman wrote:
| dangerlibrary wrote:
| So, in a conventional reactor, you use nuclear fission to
| heat/pressurize water and then use your hot, slightly radioactive
| steam turn a turbine. This mostly works because moving even very
| hot, very high pressure water around is kind of a solved problem
| in industry.
|
| In a molten salt reactor, you use nuclear fission to melt various
| corrosive salts into a fluid, and this is good because molten
| salts store a lot more energy per unit (volume, presumably?) at
| low pressures, so you can transfer heat indirectly to nearby
| turbine-turning water without irradiating the water or relying on
| high-pressure water to cool your reactor. Cool.
|
| But I was under the impression that the main stumbling block for
| molten salt reactors was that high-energy corrosion resistant
| materials for containing / moving molten salt simply don't exist
| (yet). I suppose this is less of a problem for a research
| reactor, but it doesn't sound like there's been a materials
| breakthrough here that's allowing them to get started. Are they
| just plowing forward and they'll need to replace the containment
| infrastructure every few years?
| ortusdux wrote:
| Annoyingly, "molten salt reactor" is used to describe two
| different technologies. What you describe is a traditional
| reactor that uses molten salt to move heat. This typically
| leads to higher efficiencies, but does have corrosion issues.
| Other power generation systems can also benefit from molten
| salt loops - namely solar energy collectors.
|
| In the research field, "molten salt reactors" (MSRs) usually
| means the other tech - a reactor where the fissile material is
| dissolved in a salt. This not only brings efficiency increases,
| but many safety improvements. Many designs also use a 2nd
| molten salt loop as a temperature step-down before steam power
| generation.
| jacquesm wrote:
| There have been quite a few solar energy concentrator test
| beds based on molten salt in order to try to get to 24/7
| solar power. It is an interesting technology but afaik it's
| not at the stage where it can be rolled out reliably and
| maintenance free.
| politician wrote:
| One of those safety improvements -- a freeze plug --
| passively halts the reaction in the event of a power cut. The
| reactor sits on top of a vault that has a larger volume
| separated by a narrow tube containing molten salt that has
| been frozen into a plug by cryocoolers powered by the
| turbines themselves. If the pumps stop for any reason, then
| the plug quickly melts and the molten fluid from the reactor
| drains into the larger vault via gravity at which point it
| cools and freezes into a solid.
| throwaway894345 wrote:
| Freeze plugs sound super cool, but this part breaks my
| brain:
|
| > containing molten salt that has been frozen into a plug
|
| Presumably salt can't be both molten and frozen at once, or
| is there something about this domain that I don't
| understand?
| phire wrote:
| I believe they use active cooling to keep the plug
| frozen.
|
| If the power fails, the cooling fails and the plug melts.
| throwaway894345 wrote:
| Yeah, I got that (and it seems like a really elegant
| solution! very _cool_ , pun intended, etc). My question
| was about how salt (or any other matter, really) can
| simultaneously be molten and frozen.
| el_nahual wrote:
| Part of it is molten (above the plug), part of it is
| frozen (the plug).
|
| Think pipes in a house in winter, where one little part
| of the pipe gets frozen while the rest of the pipes have
| liquid water in them.
| xorbax wrote:
| And in Spring, when the broken pipe plugged with solid
| molten ice thaws, your house's molten ice circuit
| performs an emergency evacuation into the yard, saving
| you from the convenience of adequate molten ice pressure
| ortusdux wrote:
| It can't. Well, maybe at its triple-point, but that is
| another story. It is just a quirk of the language due to
| it being know as molten salt. For example, my drink is
| full of molten water that has been frozen into cubes.
| robotresearcher wrote:
| Think of a lake in the winter. Just the top layer of
| water is frozen, exposed to the cold air above the lake.
| Some of the lake water is frozen and some is liquid,
| depending on its position in the lake.
| ortusdux wrote:
| It is literally just a tube with a fan blowing over it.
| Most designs just barely solidify it, so any over-
| temperature events also cause a passive shutdown.
| andrewflnr wrote:
| I think it was just a clumsy phrasing, with the point
| being that it's a solid plug of whatever salt is molten
| and circulating above.
| ortusdux wrote:
| One of my favorite safety elements is often over-looked:
| they operate at 1 atmosphere. So much of the cost and bulk
| of a traditional reactor is the shielding needed to protect
| from an over-pressure event.
| [deleted]
| JumpCrisscross wrote:
| Are freeze plug failures recoverable? Or is is this a final
| failsafe that toasts the reactor?
| ortusdux wrote:
| Easily recoverable. The tube drains into a collection
| tank filled with control rods, so any reactions are
| halted. You can just reheat the salt and pump it back
| into the reactor. Reportedly, one of the first test
| reactors in the 50's was shut off every Friday and
| restarted on Monday. A full power loss, what would be
| catastrophic for any other reactor, was tested weekly for
| a year without issue.
| elihu wrote:
| It seems like that might suggest a potential option in the
| search for appropriate materials to build the containment
| vessel and piping to hold in the salt: just make the whole
| thing out of salt. Anything that needs to be solid can have
| built-in channels with coolant piped through. The rest can
| maintain a sort of steady state.
|
| I'm sure there's all sorts of practical reasons why that
| wouldn't work, but it's an interesting thing to think
| about.
| lolc wrote:
| Nice hack! That sounds so easy that I wonder what the
| catch is.
|
| Maybe it would need more energy for cooling than what it
| generates? So it would have to be scaled up to a size
| where the surface-to-content ratio becomes favourable.
| There might not be enough salt for that :-)
| elihu wrote:
| I suppose one problem might be selecting an appropriate
| coolant that doesn't dissolve the salt on contact.
| Presumably water would, but google says that salt doesn't
| dissolve in oil so maybe that's an option.
|
| Ideally you wouldn't need to expend energy to keep the
| coolant cold enough; rather, you'd use the coolant to
| boil water to run your steam generator.
| pfdietz wrote:
| There are a number of obstacles. Neutron damage to the reactor
| structure is more of a problem, since the fuel is dissolved in
| salt in direct contact with that structure (unlike a reactor
| with solid fuel rods, which are separated from the reactor
| vessel by a thickness of moderator, in the case of LWRs is
| water.)
|
| See here for a (somewhat old) list of some technical issues:
|
| https://gain.inl.gov/SiteAssets/MoltenSaltReactor/Module2-Ov...
|
| "Nickel-based alloys embrittle under high neutron fluxes at
| high temperature"
|
| "Over 40% of [fission products] leave core [in offgas]"
|
| "Large fraction of cesium, strontium, and iodine end up in
| offgas"
|
| "MSRE was approaching end of allowable service life when shut
| down" (after four years at 40% capacity factor)
| samstave wrote:
| https://i.imgur.com/qX2d2qg.jpg
|
| https://i.imgur.com/InQHoSI.png
|
| https://i.imgur.com/go5v5QL.jpg
| ars wrote:
| > slightly radioactive steam
|
| For anyone worried about this, the longest lived unstable
| isotope of oxygen (that is heavier than stable oxygen) has a
| half life of 26 seconds. Hydrogen can become deuterium which is
| stable, and finally tritium which is not.
|
| Tritium has a long half life of 12 years, but is low energy and
| very easily shielded (just don't eat it).
|
| There is very very little tritium - first you'd have to make
| deuterium (there isn't much), and then a deuterium would have
| to become a tritium, i.e. a rare event on top of a rare event.
| kenned3 wrote:
| Your view really depends on the design.
|
| CANDU (Canadian reactor design) is moderated via deuterium in
| which case there is a LOT of it circulating in the reactor
| core.
|
| The heavy water is syphoned off to a tritium separation unit
| for recovery. With a market value of $30,000 a gram, there is
| a clear incentive to recover it ;)
| theluketaylor wrote:
| Some buddies who work on CANDU tell me they have tritium
| contamination everywhere as a result of this. From what
| they tell me it's not really a big safety issue, mostly
| more annoying than anything.
| YakBizzarro wrote:
| Not compltly accurate. It's true that the half-life of
| tritium is short compared to long lived actinides. However,
| like hydrogen, it diffuses very easily and it's not easy to
| contain. In fact, it's one of the few things emitted in the
| environment during normal reactor operations. As beta
| emitter, you are right that it's dangerous only when
| ingested, but it's very easy to breath of to get it from
| other ambient sources
| ars wrote:
| Very little tritium will diffuse, because it's bound with
| oxygen as water.
|
| However some water does come out of the reactor you are
| correct.
| rich_sasha wrote:
| I think one key aspect is that they are less susceptible /
| immune to loss of coolant incidents. In a PWR if there is a
| loss of pressure, or coolant in any other way, and emergency
| cooling doesn't work, the core overheats and might melt down.
|
| An uncooled pool of molten salt will keep on generating heat
| even after the reaction is stopped, so will continue heating
| up, but it is possible to design the reactor so that the whole
| thing remains stable. Since the pressure is low, there is no
| risk of explosion, or release of the radioactive materials.
|
| So the energy density is i think a secondary benefit, if at
| all.
| PaulHoule wrote:
| People thought this stuff
|
| https://haynesintl.com/docs/default-source/pdfs/new-alloy-br...
|
| (which is practically stainless steel without the steel) was
| good for this use but when it was tried in this system it did
| not hold up very well
|
| https://en.wikipedia.org/wiki/Molten-Salt_Reactor_Experiment...
|
| but it was believed that some small change in the formula such
| as adding Niobium could clear the problem up. What's needed to
| move forward is not a big conceptual breakthrough but rather
| testing of materials under realistic conditions... A new test
| reactor.
|
| What is more problematic with the MSRE design is that it
| incorporates graphite as a moderator and the graphite swells
| and goes bad over time. Possibly you can take the graphite core
| out every few years and replace it with a new one, but people
| have also found designs that don't require a moderator outside
| the fuel salt.
|
| When I went to the first conference on Thorium Energy years ago
| David Leblanc had done some very simple calculations that
| showed you didn't need the graphite -- it works just fine with
| a faster spectrum. He's refined that idea and is running with
| it. Others are pursuing chloride salts and plutonium fuel with
| a very fast spectrum.
| acidburnNSA wrote:
| Fast spectrum MSRs bring a whole litany of other problems.
| Chlorine has more oxidation states and the chemistry with
| fission products is much more complex.
|
| Starting with graphite makes sense imho for a university.
| HPsquared wrote:
| If it's designed with replacement in mind, a graphite
| moderator isn't all that bad. It can even be a safety
| advantage, in that if you drain the fuel out of the vessel
| it's taken away from its moderator.
| runarberg wrote:
| > But I was under the impression that the main stumbling block
| for molten salt reactors was that high-energy corrosion
| resistant materials for containing / moving molten salt simply
| don't exist (yet).
|
| Is this also an issue for molten salt / liquid metal
| batteries[1][2] that have been proposed as a grid scale energy
| storage solution for renewables?
|
| The way I understand it, molten salt is used as the membrane
| separating the electrode and electrolyte layers. But I was
| under the impression that there are actual molten salt
| batteries prototypes with industrial scale facilities currently
| under construction.
|
| Are the requirements to contain the molten salt in a battery
| different from a nuclear reactors? Or do they have the same
| challenges and are simply able to overcome economic feasibility
| whereas nuclear reactors aren't?
|
| 1: https://ambri.com/
|
| 2: https://www.youtube.com/watch?v=-PL32ea0MqM
| marcosdumay wrote:
| Molten salt / liquid metal batteries normally use alkaline
| salts, so steel holds it pretty well.
| Manuel_D wrote:
| > So, in a conventional reactor, you use nuclear fission to
| heat/pressurize water and then use your hot, slightly
| radioactive steam turn a turbine.
|
| Only in the more primitive reactor designs (BWR, Boiling Water
| Reactor). Most are of the PWR, Pressurized Water Reactor,
| design. In these, the water in the reactor is still liquid due
| to being held at pressure. This pressurized water is run
| through a steam generator [1] that boils non-radioactive water
| that never comes into contact with the reactor.
|
| 1.
| https://en.wikipedia.org/wiki/Steam_generator_(nuclear_power...
| acidburnNSA wrote:
| > Only in the more primitive reactor designs (BWR, Boiling
| Water Reactor).
|
| TRIGGERED :).
|
| The BWR was developed after the PWR specifically to be more
| economical for terrestrial large-scale power generation. The
| PWR was designed to be compact and to work on a submarine. So
| the BWR is the more advanced design for power plants,
| arguably.
|
| https://whatisnuclear.com/reactor_history.html#the-
| developme...
| pnw wrote:
| I hope we manage to improve the design over the 1960s version
| MSRE which cost $130m to clean up due to unforeseen problems
| including a near-criticality incident. Certainly there is a lot
| of research to be done.
| PaulHoule wrote:
| The cause of the criticality accident was that they did not
| remove the uranium when they were done with it. This is
| straightforward to do, you pump F2 gas into the salt and this
| gas is produced
|
| https://en.wikipedia.org/wiki/Uranium_hexafluoride
|
| which can be stored in tanks. Instead of removing it they let
| the salt sit, and radioactive decay led to F2 gas being
| produced by the salt, which caused UF6 to be produced slowly
| and then migrate.
|
| This mistake won't happen again.
| p1mrx wrote:
| > corrosion resistant materials for containing / moving molten
| salt
|
| I'm interested to see what Moltex can do to simplify matters:
|
| https://www.youtube.com/watch?v=7qJpVClxzVM&t=758s
|
| Instead of pumping the salt around, they plan to leave it
| sitting in stainless steel tubes, and use simple convection to
| extract the heat. Oak Ridge rejected this idea in the 1950s
| because they were trying to power an aircraft, but convection
| makes more sense when the reactor isn't moving.
| acidburnNSA wrote:
| LANL built a reactor like that, with liquid fuel in tungsten
| capsules. It was called LAMPRE.
|
| https://www.osti.gov/biblio/4368180-operation-plutonium-
| fuel...
| sophacles wrote:
| > So, in a conventional reactor, you use nuclear fission to
| heat/pressurize water and then use your hot, slightly
| radioactive steam turn a turbine.
|
| I was under the impression that there was a heat exchanger in
| the path - that is the reactor turns water into slightly
| radioacive steam, which is sent through a heat exchanger to
| turn different water into non (or way less anyway)- radioactive
| steam for the turbines. So both are indirect.
|
| (This is just a nit comment, I think your main points about
| efficiency still hold, and your materials questions are good!)
| nine_k wrote:
| Exactly. In other variants of reactors the inner contour
| could circulate molten slightly radioactive sodium instead.
| dangerlibrary wrote:
| That makes a lot of sense.
|
| I think I was confused by news stories about situations where
| the reactor has failed in some way, and then there are
| stories of how radioactive water needs to be stored /
| disposed of somehow.
| marcosdumay wrote:
| Also, AFAIK, those high-temperature reactors are normally
| made with a molten metal intermediate cycle (normally sodium)
| and a gas-only external cycle (normally CO2).
|
| Water enters only to cools the cold side of the external
| cycle.
| philipkglass wrote:
| There are two kinds of conventional light water reactor. In
| the pressurized water reactor (PWR), the most common, there
| is indeed an additional heat exchanger between the water in
| the core and the water that turns to steam. In the boiling
| water reactor (BWR), the second most common, the slightly
| radioactive steam from the core goes directly to a turbine.
|
| https://en.wikipedia.org/wiki/Boiling_water_reactor
| tadfisher wrote:
| Correct, in a PWR or BWR the hot side is in a closed loop.
| There's a great PDF here: https://www.nrc.gov/reading-
| rm/basic-ref/students/for-educat...
| ortusdux wrote:
| You are correct about the corrosion issue. I've done some work
| developing molten salt resistant claddings. The main culprit is
| chromium leaching, which de-alloys most of the metals approved
| for reactor design. The leeching happens at the grain
| boundaries, so you will hear 'intergranular attack' as a
| research focus.
|
| A close second problem is the radiation itself. Elements in
| both the containment vessel and salt transmute. One study I
| read estimated that pure tungsten (a viable salt resistant
| material) would transmute to rhenium at a rate of 1% a year.
| The radiation also causes void-swelling in both the metals and
| pure graphite.
|
| The standard way to test material's resistance to molten salt
| is to put a coupon in a crucible full of salt for a few hundred
| hours. A paper from 2015 showed that the material the testing
| crucible is made of greatly effects the rate of chromium
| leeching. They found that both graphite and nickel act as
| chromium sinks. Many designs call for graphite or nickel parts
| to be used alongside chromium containing steels. This reactor
| appears to be stainless steel with graphite moderators.
|
| Another paper strongly suggested that radiation induced void-
| swelling can squeeze together the grain boundaries, greatly
| slowing down intergranular attack. Very little corrosion
| testing has been done under exposure to radiation as it is
| logistically difficult.
|
| Basically, the next best step is test reactors. You can only
| get so far testing things in isolation.
| HPsquared wrote:
| Does it even need to be a metal? (Since the pressure is so
| low strength requirements are lower)... How about ceramic or
| glass (or quartz), or something else non-metal?
| kenned3 wrote:
| non-metals have their own problems and glass tends to have
| some really weird properties.
|
| I would think a major one would be their failure mode.
| Metals flex and expand before they eventually fail.
| Glass/ceramic is fine until suddenly it isn't and has a
| total failure.
|
| Think of a window being hit. If it were metal it would
| probably deform but if it is glass it shatters.
|
| Next would be joining them on-site. If needed, metal piping
| can be bent and welded in-place. what do you do with a
| glass pipe that needs a join? what do you do if there is a
| small variation in the plans and the pipe needs an
| adjustment?
|
| I think there are a host of reasons why glass is not used
| for pipes.
| systemvoltage wrote:
| Composites? Such as the stuff used in Aviation?
| [deleted]
| Turbots wrote:
| what about glass pipes encased in said metals :-)
| HPsquared wrote:
| Glass-lined vessels and pipes are already used in the
| chemical industry so it's a somewhat proven technology.
|
| Not sure if it's suited to the chemistry and temperatures
| (and radiation) of a molten salt reactor, but it seems
| like an interesting technology.
| [deleted]
| mjul wrote:
| Molten salt loops are not as difficult with current technology
| as they were when they were first introduced.
|
| There are some very interesting startups in this field working
| on delivering these reactors on an industrial scale rather than
| the "artisanal" reactors that dominate today:
|
| Copenhagen Atomics [1] is one. They offer a molten salt loop
| for rapid prototyping [2] if you want to try it yourself.
|
| Seaborg Technologies is also building a compact molten salt
| reactor. [3] They have a subsidiary, Hyme, to use the same
| molten-salt technology to provide grid-scale energy storage to
| balance electricity grids with variable generation from e.g.
| wind and solar power. [4]
|
| [1] https://www.copenhagenatomics.com/ [2]
| https://www.copenhagenatomics.com/products/molten-salt-loop/
| [3] https://www.seaborg.com/ [4] https://www.seaborg.com/press-
| release-hyme
| notacop31337 wrote:
| Anyone know of any software work being done around Nuclear? I
| don't care what it is, just looking to play a bit more with the
| space, Open Source, data sourcing. I really mean I don't care
| what it is, just wanna learn a bit more about it and be a bit
| more involved.
| marcosdumay wrote:
| A 1MW research reactor.
|
| Anyway, why is it always a fluoride salt? Is it because of the
| melting point or because of some nuclear property?
|
| I imagine there is some very relevant reason, because a less
| reactive anion (even chlorine) would be much easier to work with.
| detaro wrote:
| https://en.wikipedia.org/wiki/Molten_salt_reactor#Fused_salt...
| pfdietz wrote:
| Because fluorine has a low neutron capture cross section.
|
| Chlorine has a rather high capture cross section for thermal
| neutrons, so it could only be used in fast reactors.
| nickpinkston wrote:
| Good question - here's a paper and quote on this:
|
| "Molten Salt Reactor (MSR) was designed to operate at high
| temperature in range 700 - 800degC and its fuel is dissolved in
| a circulating molten fluoride salt mixture. Molten fluoride
| salts are stable at high temperature, have good heat transfer
| properties and can dissolve high concentration of actinides and
| fission product."
|
| https://aip.scitation.org/doi/10.1063/1.4972932
| thereisnospork wrote:
| Without knowing the specifics as apply to nukes, anion
| reactivity is inversely proportional to atomic reactivity,
| fluoride is far _less_ reactive than chloride or bromide or
| iodide, respectively in order of increasing reactivity. Ergo
| fluoride and fluoride containing anions are quite common in
| molten salts /ionic liquids.
|
| In English: the flouride, having so voraciously devoured that
| 8th electron it was missing, _really_ doesn 't want to give it
| up, whereas chlorine et al have lots of spares.)
| marcosdumay wrote:
| The concern is not so much about the fluoride losing an
| electron, but about whatever reacted to it stealing electrons
| from the reactor.
| thereisnospork wrote:
| Which is less likely with fluorine because what fluorine
| reacts with to form the salt, say Na as in NaF, wants to
| give up an electron, not receive one. And with fluorine as
| a partner, Na will have the hardest* time retrieving that
| electron to give to something else. This can be easily
| validated by comparing enthalpy of reaction and formation
| for the various halide salts.
|
| The properties of broad chemical stability are not limited
| to ionically bonded fluorine either, see PTFE, which also
| derives its stability from the extreme reactivity of
| fluorine. Compared to say PTIE (polytetra _iodo_ ethylene),
| which if you could even make would rapidly yellow and
| degrade in open air/mild sunlight, as iodine compounds are
| wont to do.
|
| *for a loose definition of hardest.
| LatteLazy wrote:
| It is very stable both chemically and atomically.
| PaulHoule wrote:
| Fluoride salts are good for fissile uranium + fertile thorium.
| If you want to work with a plutonium/uranium 238 cycle then
| chloride salts are a better choice. Plutonium doesn't dissolve
| very well in fluorides.
|
| Molten chloride reactors can have performance characteristics
| right out of science fiction, it seems possible for such a
| reactor to not only breed more fuel but to destroy the long-
| lived (500 year) fission products such as cesium and strontium.
|
| It never gets upvoted on HN when I link it but I've been
| following MSRs for a while and even spoke at the first thorium
| energy conference and I've been watching people's thoughts
| about designs evolve and this one
|
| https://www.moltexenergy.com/
|
| is well ahead of the others.
| throwaway894345 wrote:
| > We can produce heat for hydrogen, replacing the need for
| fossil fuels in heating, transport and industry.
|
| What does it mean to produce "heat for hydrogen"? Why is
| heating hydrogen a useful property (how does hot hydrogen
| replace fossil fuels in heating, transport, and industry?)?
| That seems oddly specific, so I assume I'm misreading
| something?
| nullc wrote:
| Thermochemical water cracking.
| nine_k wrote:
| While at it, I never understood the worry about the plutonium
| surfacing in the MSR cycle. Of course it can be diverted to
| make nuclear warheads. But countries like the US, or France,
| or Russia, or China, or India already are able to produce
| nuclear warheads, even from plutonium extracted from more
| conventional reactors. I don't understand where is the risk
| of proliferation.
|
| Is this about international treaties and ease of inspection?
| About currently non-nuclear countries obtaining nuclear
| weapons more easily?
| PaulHoule wrote:
| (1) There is fear that any advance in nuclear power
| technology will lead to corresponding advances in nuclear
| weapons technology. For instance, if somebody built a
| perfect system for separating out protactinium from a
| thorium MSR, that protactinium could be allowed to decay
| outside the reactor and produce pure U233 that could be
| used to make weapons. That perfect system is probably not
| practical, but in general there is fear that any new
| approach to fuel processing could have unintended
| consequences. Would it be possible, for instance, to make
| something like the EBR-II that breeds weapon grade
| plutonium in a blanket and uses some form of pyroprocessing
| to produce pure metallic plutonium? Such a system might be
| able to make enough material to build several weapons a
| year.
|
| (2) The published information about nuclear proliferation
| is incomplete and the mental models behind it are broken.
| For instance, the "little boy" bomb was made with uranium
| produced with a
|
| https://en.wikipedia.org/wiki/Calutron
|
| but for all the fear that countries like Iran would develop
| centrifuges, there has been little fear expressed about
| Calutrons... Except that when Iraq tried to develop a bomb
| it used the exact same approach used by the US! A scientist
| at CERN had been contacted by an Iraqi scientist who was
| interested in a magnet which could have been used for a
| Calutron and the proliferation authorities just blew him
| off.
|
| See
| https://nuclearweaponarchive.org/Iraq/andre/ISRI-95-03.pdf
|
| A country like Japan has large amounts of plutonium which
| is contaminated with Pu240 and Pu241 and not weapons usable
| but it's plausible that a modified Calutron could be used
| to purify non-weapons grade plutonium and make it weapons
| grade.
|
| Although the conventional model is that a threat would make
| plutonium by irradiating uranium with neutrons from a
| fission reactor, it's also possible that a fusion reactor
| or particle accelerator could be used as a neutron source
| to do the same. The later would actually have less heat
| output per unit of Pu and might be an easier device to
| hide. Current particle accelerators aren't reliable or
| economical enough for this purpose, but this is just one of
| many paths to proliferation which are ignored.
| aidenn0 wrote:
| I can't find a source, but my recollection is that the
| majority of the U-235 for Little Boy was generated by
| gaseous diffusion? I know the original process was
| gaseous-diffusion followed by Calutron and that once
| gaseous diffusion was improved they shut down all of the
| Calutrons, and the timing is such that all but the first
| little boy bomb must have been made by gaseous diffusion,
| but it's unclear how the fissile material for the bomb
| dropped on Hiroshima was generated.
| colechristensen wrote:
| Perhaps it's just how much more careful you have to be with
| plutonium products because of proliferation concerns, or
| possibly diplomacy concerns "legitimizing", or perhaps just
| paranoia. Or the basic concern of a bunch more plutonium
| hanging around even if secure.
| hedora wrote:
| It's pretty cool that they designed their plants with a heat
| reservoir and oversized turbine generators. This allows them
| to turn the turbines on and off at will, complementing wind
| and solar. The nuclear plant "charges" the heat reservoir
| during the day when the turbines are idle.
| thoughtpeddler wrote:
| Forgive me if this is a naive question, but how are molten salt
| reactors different from the reactor in the 1959 Sodium Reactor
| Experiment [1]?
|
| [1]
| https://www.etec.energy.gov/Operations/Major_Operations/SRE....
| EricE wrote:
| Way, way overdue! China has taken all of our research from the
| 50's and has been charging ahead. Very sad that politics and
| ignorance has severely kneecapped our nuclear industry :(
| powerhour wrote:
| It's also sad that industry completely failed to convince the
| population that they can provide a safe solution. For all the
| credit we give BigCo for creating propaganda, it's curious that
| they were unable to be successful here, given the stakes.
| 2OEH8eoCRo0 wrote:
| They are up against big fossil fuel tycoons like the Kochs.
| If we are strictly talking corporate propaganda, the fossil
| fuel industry has plenty of that.
| powerhour wrote:
| It seems to me that companies like GE and Westinghouse have
| tons of money. Add that to the billions pro-nuclear folks
| have in SV and you've got quite the war chest to fund
| effective pro-nuke campaigns.
| throwaway894345 wrote:
| Those folks might not want to waste that money in a
| propaganda race against the entire fossil fuel industry
| and the emerging renewable energy industry. GE and
| Westinghouse are large and successful companies, but is
| nuclear a major part of their portfolio such that they
| would take such a big risk (compared to fossil fuel
| industry which views clean energy as an existential
| threat)?
| phonon wrote:
| Westinghouse went bankrupt a few years ago[0]...and GE
| hasn't been doing well and is splitting up[1]...
|
| [0]
| https://www.nytimes.com/2017/03/29/business/westinghouse-
| tos...
|
| [1] https://www.usnews.com/news/business/articles/2022-07
| -18/ge-...
| PaulHoule wrote:
| As much as people portrayed an epic battle between
| renewables and nuclear the real winner from the move away
| from nuclear was natural gas fired gas turbines.
|
| The most obnoxious thing about the energy literature is
| that it frequently reads like a stopped clock. People still
| compare the cost of nuclear energy to the cost of coal, but
| it's no accident that the US stopped building coal plants
| at the same time it stopped building nuclear plants because
| it stopped both for the same reason... The capital cost of
| a gas turbine generator (even in a hybrid cycle including a
| steam turbine) is dramatically smaller than the steam
| turbines used in coal and nuclear plants.
|
| Since molten salt reactors run a lot hotter than LWRs they
| could drive
|
| https://en.wikipedia.org/wiki/Closed-cycle_gas_turbine
|
| but it's a technology that is not very well developed. If
| nuclear energy is going to compete with natural gas,
| however, they need to ditch the steam turbine.
| wpietri wrote:
| For sure. In theory, I'm in favor of nuclear power;
| especially as we try get to zero/negative net carbon
| emissions, nuclear plants have real advantages. But when I
| think about American business culture, I have a hard time
| imagining the company I'd trust with something that requires
| an extremely long-term focus (plants run for decades) and
| deep social responsibility.
| Galaxeblaffer wrote:
| Energy too cheap to meter doesn't sound like a good
| investment from a capitalistic viewpoint.
| martin1975 wrote:
| So did the Chinese beat us to this one? :)
| acidburnNSA wrote:
| Yes they're turning on their graphite moderated MSR reactor
| that's fully constructed in the next few days? weeks? not
| entirely sure, but soon.
|
| https://www.world-nuclear-news.org/Articles/Chinese-molten-s...
| mikewarot wrote:
| I'm surprised the reactor needs a moderator, I would assume that
| a liquid fuel reactor could be controlled far better by
| controlling flow into and out of the critical mass. It's all at
| normal pressures, just hot (temperature and radiation wise), so
| just bog standard plumbing practices for handling fluid levels
| should work.
|
| Being able to scramble the reactor by just dumping the contents
| through a set of diverters into separate flat bottom chambers to
| cool and eventually freeze is an awesome safety feature.
| YakBizzarro wrote:
| A moderator is not used to control the reaction, but to make it
| possible. The neutrons produced by fission, have high kinetic
| energy, and fuel has a small cross section for neutrons at such
| high energy. A neutron moderator slows down the neutrons,
| making them more likely to interact with the uranium and split
| them. typically water is a good moderator, but here they use
| graphite for obvious reason (high temperature salts doesn't
| play well with water)
| mikewarot wrote:
| That makes a lot of sense... thanks!
|
| As for molten salts and water... oh yeah. That gets into very
| dangerous territory.[1] A very similar reaction seems to
| happen even with just molten table salt, where it
| "shouldn't". 1 -
| https://www.youtube.com/watch?v=LmlAYnFF_s8
| indymike wrote:
| This is really exciting. Fission tech is largely stuck in with
| incremental improvements from the 1950s. The last time the NRC
| got an application for a research reactor was 30 years ago.
|
| The reactor is a graphite-moderated, fluoride salt flowing fluid
| design. If this works well, fission will have a very bright
| future as it should be more efficient and much safer to operate
| than current reactor designs.
| rob_c wrote:
| Yey! About time :) hopefully this gains serious traction
| AtlasBarfed wrote:
| I thought these were outlawed, per a LFTR video I saw once. To
| emphasize, I'm asking if that is the case, or was the LFTR video
| was engaging in misinformation, or if something changed in
| regulations.
| mrunkel wrote:
| LFTR?
| acidburnNSA wrote:
| LFTR is just a trade name from a guy named Kirk who tried to
| rebrand the Thorium fueled Molten Salt Reactor.
|
| So basically yes but like all thorium reactors it has to
| start with enriched uranium first.
| jussion_zoonist wrote:
| Liquid Fluoride Thorium Reactor but I believe this reactor is
| using uranium[1].
|
| [1] https://www.nrc.gov/docs/ML2024/ML20241A071.pdf
| Kalium wrote:
| I believe it's less outlawed and more not really approved for
| use due to insufficient research.
| PaulHoule wrote:
| The process for licensing a LWR is well established.
| Commercial LMFBR (Fermi 1) and HTGR (Peach Bottom 1) reactors
| have been approved in the US but those were a very long time
| ago. Anybody who wants to license a new reactor type is going
| to work through an extensive process with the NRC to
| determine how exactly it is done.
|
| They built an MSR in Wuwei, China and just got approval to
| start it.
|
| https://www.world-nuclear-news.org/Articles/Chinese-
| molten-s...
| nine_k wrote:
| AFAICT materials research is a big part of it. At 800degC
| even water is pretty reactive; the salt is much more so. Even
| though an MSR does not need the high pressure of water-based
| reactors, you can't make all the piping from graphite or
| platinum.
| philipkglass wrote:
| I believe that the video was misinformed or your recollection
| is a bit fuzzy. The closest true approximation I can muster is
| "there is no commercial molten salt reactor design yet approved
| by the NRC, and the NRC approval process may need updates to
| consider reactor designs that significantly deviate from the
| common water-moderated types."
| peteradio wrote:
| Yes, they are illegal to build.
| formerkrogemp wrote:
| It's cool to see what the hottest research is in NA these days,
| even if they're being so salty about it.
| dang wrote:
| Related. Others?
|
| _DOE digs up molten salt nuclear reactor tech, Los Alamos to
| lead the way back_ -
| https://news.ycombinator.com/item?id=32423177 - Aug 2022 (1
| comment)
|
| _Chinese molten-salt reactor cleared for start up_ -
| https://news.ycombinator.com/item?id=32406435 - Aug 2022 (9
| comments)
|
| _Stable Salt Reactor_ -
| https://news.ycombinator.com/item?id=32233485 - July 2022 (2
| comments)
|
| _What is a molten salt reactor?_ -
| https://news.ycombinator.com/item?id=31187423 - April 2022 (101
| comments)
|
| _1MW Molten-Salt Test Reactor by Copenhagen Atomic for EUR88k
| [video]_ - https://news.ycombinator.com/item?id=25388343 - Dec
| 2020 (198 comments)
|
| _New Design Molten Salt Reactor Is Cheaper to Run, Consumes
| Nuclear Waste_ - https://news.ycombinator.com/item?id=24771306 -
| Oct 2020 (2 comments)
|
| _ThorCon 2019 500MW molten salt modular tow-able nuclear reactor
| [pdf]_ - https://news.ycombinator.com/item?id=21307378 - Oct 2019
| (2 comments)
|
| _Molten Salt Reactors_ -
| https://news.ycombinator.com/item?id=20424841 - July 2019 (120
| comments)
|
| _What Is Called Nuclear Waste Is Mostly Fuel for Molten Salt and
| Fast Reactors_ - https://news.ycombinator.com/item?id=20191064 -
| June 2019 (49 comments)
|
| _Open source Molten salt nuclear reactor design_ -
| https://news.ycombinator.com/item?id=18892919 - Jan 2019 (88
| comments)
|
| _Remote Maintenance of Molten Salt Reactors [video]_ -
| https://news.ycombinator.com/item?id=15543428 - Oct 2017 (6
| comments)
|
| _A Thorium-Salt Reactor Has Fired Up for the First Time in Four
| Decades_ - https://news.ycombinator.com/item?id=15084215 - Aug
| 2017 (161 comments)
|
| _Molten Salt Reactor Claims Melt Down Under Scrutiny_ -
| https://news.ycombinator.com/item?id=13863626 - March 2017 (137
| comments)
|
| _The 500MW molten salt nuclear reactor_ -
| https://news.ycombinator.com/item?id=5371659 - March 2013 (22
| comments)
___________________________________________________________________
(page generated 2022-08-22 23:00 UTC)