[HN Gopher] Natrium 'advanced nuclear' power plant wins Wyoming ...
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Natrium 'advanced nuclear' power plant wins Wyoming permit
Author : chiffre01
Score : 44 points
Date : 2025-01-15 19:58 UTC (3 hours ago)
(HTM) web link (wyofile.com)
(TXT) w3m dump (wyofile.com)
| smaddox wrote:
| > That application was submitted in March 2024 and is on track
| for approval in December 2026
|
| Huh? Is this something where there's multiple incremental steps
| in the process, and that date is just the final approval stamp,
| or does it actually just take more than 1.5 years?
| bpodgursky wrote:
| It's always fun seeing someone jump into NRC discourse for the
| first time.
| daedrdev wrote:
| I'm pretty sure this is extremely fast for the nuclear
| industry.
| myheartisinohio wrote:
| Feds
| simplicio wrote:
| I'm generally pretty open to the idea that the NRC is bad and
| needs to be reformed, but a year and a half doesn't seem that
| unreasonable? Especially for a new reactor design.
| nine_k wrote:
| I hope this involves a lot of much faster feedback /
| modification cycles, and the process ends when all the feedback
| has been addressed.
| pfdietz wrote:
| This is a fast reactor. That is, a reactor in which the neutrons,
| instead of being moderated down to thermal energies, remain at
| high energy.
|
| The fission cross section for such energetic neutrons is much
| lower than for thermal neutrons. Therefore, there has to be a
| much greater density of fissionable material in the reactor core.
|
| The lack of a moderator also means rearrangement of the core in
| an accident is potentially much more dangerous. If the fuel
| itself rearranges to become more compact, say by melting and
| flowing, the reactivity could increase. This is not possible in
| (say) a light water reactor, where such a rearrangement would
| reduce reactivity.
|
| The nightmare scenario for any fast reactor, warned about by
| Edward Teller in 1967, is a rearrangement that causes the core to
| become supercritical on prompt neutrons alone (that is, on only
| the neutrons released promptly at the moment of fission, not on
| those + the delayed neutrons emitted by some fission products as
| they decay). A fast prompt supercritical configuration could
| potentially explode with great violence, greater than Chernobyl.
| An atomic bomb is a prompt fast supercritical system.
|
| I will want to see how the NRC does or does not license their
| design, a process that has just started. I will not be surprised
| if their approach ends up being unlicensable in the US because
| safety cannot be assured by analysis under accident conditions.
| thecopy wrote:
| Based on your comment it sounds unreasonable to select this
| design. It must have some reason to exist?
| pfdietz wrote:
| Fast reactors do have some attractive features. They have
| better neutron economy and work better with plutonium. They
| can achieve breeding ratios comfortably above 1 with the U-Pu
| system. They produce less actinide waste since the chance of
| neutron capture not causing fission is lower, and can more
| effectively destroy actinide waste. Sodium-cooled fast
| reactors will operate at higher temperature than LWRs,
| enabling the salt thermal storage scheme they propose to use.
|
| In large reactors, these features have not been enough to
| compensate for the disadvantages and sodium-cooled reactors
| have not been successful, coming in more expensive than light
| water reactors for a given power output. France, which had
| been developing fast reactors, has recently mothballed the
| effort with no plan to restart before 2050.
| aidenn0 wrote:
| The main advantages of using a fast reactor are less nuclear
| waste and more energy for a given fuel input.
| nine_k wrote:
| Even _burning_ some of the "nuclear waste" which is just
| nuclear fuel than needs refining.
| manvillej wrote:
| reddit had a nice list of the pros and cons:
| https://www.reddit.com/r/NuclearPower/comments/17k0wcc/natri...
|
| I understand the risks around sodium, but the "passive natural
| circulation cooling" I don't understand. Is it more feasible
| with this design and why?
|
| " Pros: high temperature means we can use
| process-heat which is a much more efficient use of heat.
| fast spectrum neutrons means we can burn importantly
| troublesome parts of nuclear waste. fast spectrum
| is also better for breeding new fuel, significantly increasing
| how much energy we can extract from uranium/thorium.
| passive natural circulation cooling is much more feasible.
|
| Cons: fast spectrum is a little more
| complicated to control. fast reactors require high
| enrichment. inspection of the plant is very
| difficult with liquid metal. high temperature
| liquid metal doesn't play nicely with metal pipes.
| sodium burns in air and is explosive with water.
| we simply do not have nearly as much experience with sodium as
| we do water and that really cannot be understated. "
| nine_k wrote:
| I suppose that "passive natural circulation cooling" means
| that plain convection of the coolant(s) is sufficient to cool
| the reactor, without involving pumps which could fail.
| Convection can't fail as long as there is coolant and no
| significant obstacles.
| AnthonyMouse wrote:
| > If the fuel itself rearranges to become more compact, say by
| melting and flowing, the reactivity could increase.
|
| Wouldn't you just design the shape of the reactor so that if it
| got too hot for any reason, the shape it would melt into would
| result in a less compact geometry that would slow down rather
| than speed up the reaction?
| pfdietz wrote:
| How do you do that in a way that's amenable to conclusive
| analytic demonstration? For example, how do you prevent
| melted fuel from flowing into the cooling channels that go
| through the core?
|
| About the only approach I'd be comfortable with would be
| dissolving the fuel in molten salt (probably chloride salt).
| This is not Natrium's approach.
|
| Melting of fuel is not a theoretical problem -- it has
| actually happened at two fast reactors in the US (EBR-1 and
| Fermi-1, the latter the reactor in the hyperbolically titled
| book "We Almost Lost Detroit"). No explosions occurred, but
| it's very troubling the fuel melted at all. The NRC will
| surely insist on analysis of the consequences of partial fuel
| melting accidents.
| AnthonyMouse wrote:
| To begin with you might start with a geometry which by
| design is already close to maximally compact, so that a
| geometry change would tend to go in one direction.
|
| > For example, how do you prevent melted fuel from flowing
| into the cooling channels that go through the core?
|
| Expect that to happen and use a geometry that doesn't cause
| the reaction to increase in speed if it does, e.g. because
| fuel flowing into the cooling channels would make the fuel
| less rather than more compact.
| gpm wrote:
| Slightly hesitant to jump in since pfdietz definitely
| knows more about this than I do... but...
|
| Cooling typically means things like maximizing surface
| area, minimizing the thickness of the object being cool,
| etc.
|
| Maximum neutron density presumably happens in a sphere,
| which is coincidentally the shape that _minimizes_
| surface area.
|
| The whole point of a nuclear reactor is that it heats up,
| and you can convert that heat into useful fuel.
| Presumably that means you need to carry quite a lot of
| heat away per volume. Presumably that means putting the
| fuel into a spherical shape really doesn't work that
| well.
| wbl wrote:
| Why would fuel melting be possible? The way I'd show it is
| by having the increased Doppler broadening and thermal
| conductivity and lots of headroom make that sort of
| accident impossible.
| nine_k wrote:
| > _That application was submitted in March 2024 and is on track
| for approval in December 2026_
|
| Next time you complain that waiting for a code review approval
| till next week is excruciatingly long, think about these
| turnaround times.
|
| Also this is why we can't quickly build many reactors to ramp up
| electric generation for millions of new electric cars, etc.
| bryanlarsen wrote:
| The grid connection backlog is about 6 years, so this is
| considerably quicker than for a renewable energy project that
| requires a new grid interconnect.
| threeseed wrote:
| > why we can't quickly build many reactors
|
| No. The reason is that they have not been price competitive
| with renewables.
|
| And so there isn't the volume of approvals that gives
| regulators experience which in turn reduces approval times.
|
| Commercial solar takes months to approve by comparison.
| nobodyandproud wrote:
| Did we cannibalize some of our nuclear warheads, in order to get
| the enriched uranium?
|
| https://wyofile.com/fate-of-natrium-nuclear-plant-may-depend...
| nine_k wrote:
| Apparently yes, accoriding to [CNN].
|
| _" In the current stockpile, the average duration since a
| warhead was manufactured or refurbished is roughly 28 years."_
| [DoE]. I suppose some of the aging warheads will be reprocessed
| as fuel.
|
| [CNN]: https://www.cnn.com/2024/09/09/climate/nuclear-warheads-
| hale...
|
| [DoE]: https://www.energy.gov/nnsa/us-nuclear-weapons-stockpile
|
| (Previous version of this comment was incorrect.)
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