[HN Gopher] What Is a Nuclear Microreactor?
___________________________________________________________________
What Is a Nuclear Microreactor?
Author : rbanffy
Score : 124 points
Date : 2021-05-12 17:54 UTC (5 hours ago)
(HTM) web link (www.energy.gov)
(TXT) w3m dump (www.energy.gov)
| Animats wrote:
| Sounds like a TRIGA reactor.[1]
|
| Those work fine, but are not cost-effective power sources.
| They're more for isotope production.
|
| There's a Russian reactor in this category, the RITM-200.[2] It's
| a land-based version of their current generation icebreaker power
| plant. This is one of the very few "small modular reactors" that
| actually exists. There are about 30 proposed designs.
|
| Here's the first real power reactor in that category. From 1957.
| [3]
|
| [1] http://www.ga.com/triga/
|
| [2] https://en.wikipedia.org/wiki/RITM-200
|
| [3] https://archive.org/details/FirstPri1957
| amelius wrote:
| Are these reactors also used in nuclear-powered submarines?
| baybal2 wrote:
| Yes, the smallest one in existence is a submarine reactor
| once designed to power underwater spy gear
| savant_penguin wrote:
| I watched a video about the economics of nuclear reactors and the
| main focus was that the time it takes to break even is much
| longer for nuclear reactors if compared to coal and natural gas.
| Couldn't something like those microreactors solve that problem?
| baybal2 wrote:
| > Couldn't something like those microreactors solve that
| problem?
|
| No, they will actually make the problem worse.
|
| Maybe it was a somewhat valid idea 40 years ago, but bot today.
| pydry wrote:
| In theory but they're still vaporware.
| economusty wrote:
| That's the goal smaller safer and economies of scale,
| PowerPoint size reactor complexes are rarely built and are one
| off designs with high level similarities.
| Symmetry wrote:
| The main issue is that the first thing you have to do is secure
| your financing then you're paying interest on your loans over
| the near decade it takes for the regulatory approval apparatus
| to do its thing. If this allows you to get approval for a one
| reactor site with the right to expand to 24 more reactors of a
| given design without re-approval it might be very significant.
| ansible wrote:
| The other issue is that each nuclear reactor site is
| effectively unique. So there's whole piles of paperwork that
| need to be checked and re-checked to ensure that all
| procedures and everything is correct and up-to-date.
|
| With small modular reactors and similar, all the critical
| bits are made on a production line, and completely
| standardized. This will drastically reduced the paperwork and
| training needed to operate it safely.
| Teknoman117 wrote:
| Made me think of a seemingly abandoned LLNL project for what is
| in effect an autonomous breeder cycle reactor that serves as a 30
| year 100 MWe nuclear battery.
|
| https://en.wikipedia.org/wiki/Small,_sealed,_transportable,_...
| korethr wrote:
| So, do these operate on the same design principles as the various
| Gen 2 reactor designs that have been involved in nuclear
| accidents, e.g. Three Mile Island, or Fukushima? I raise this
| question not out of an anti-nuclear hysteria, but a wondering if
| the safety issues that seem inherent in those designs are
| addressed in these micro-reactor designs.
|
| I'm not particularly worried about shutdown mechanisms, but more
| so about containment of decay heat after an emergency shutdown
| event. By my understanding, our current reactor designs still
| produce decay heat for a time after shut down, and that heat
| still needs to be dealt with. And it was this decay heat and the
| failure to control it that lead to the Three Mile Island and
| Fukushima incidents.
|
| Decay heat isn't a concern for naval reactors because 1) they're
| much smaller than a commercial power reactor, with order(s) of
| magnitude less output, and 2) they have the ocean to use as a
| heat sink to prevent overheating. Micro-reactors probably also
| have the first advantage, with outputs ranging from 1-20 MW.
| However, 60-1200 kW is still not as easily shrugged off when you
| don't have an ocean to dump heat into. IME, 60-1200kW is enough
| to heat steel, if not to melting, to certainly a loss of
| strength, and that does give me some worry about damage to
| containment.
|
| So I guess my main concern is thus: Are these things being
| designed to be able to safely shed their worst-case heat
| completely passively in an emergency?
|
| If so, awesome, and I look forward to the possibilities these
| designs open up.
| godelski wrote:
| The shutdown mechanisms are specifically about the containment
| of heat. The problem is generally about a reaction not being
| shut off. Gen 3 and beyond reactors, which includes these,
| don't have these problem at all. But neither do Gen 2's,
| anymore.
|
| But if we're going to talk about the 3 accidents, we should
| note that they are quite different.
|
| Chernobyl was a positive pressure reactor. Only the Russians
| were ~~dumb~~interested in building these. Everyone else was
| afraid because their ability to explode and instead chose
| reactors that couldn't explode. The accident happened not just
| because of this, but because the xenon spike and not a great
| understanding of the science.
|
| TMI had a bunch of things go on at once. Relief valve stuck
| open but indicating close. Not enough water during SCRAM.
| Turning off ECCS due to bad indications. Then the hydrogen
| explosion. Resulting in about a dental x-ray's worth of
| radiation for a limited number of people. We now have hydrogen
| absorbers and have upgraded reactors to ensure these events
| don't happen again. [0] (this channel also talks about all the
| events).
|
| Fukushima was caused by the largest earthquake and tsunami ever
| recorded in the region (so lower bounding to 1k year event) and
| one of the largest ever recorded anywhere. The reactors were
| designed to withstand quakes and tsunamis. The tsunami and
| earthquake were much larger than anyone expected to ever happen
| in the region. Reactor got destroyed and it is hard to track
| where all the material went, which is why they have the region
| closed down (background radiation levels aren't so bad, but you
| don't want to risk consumption of reactor material. Similar to
| why the surrounding area of Chernobyl is closed).
|
| The reason I bring all these up is because we should note that
| even Gen 2 reactors have been retrofitted with improvements
| from these events, and have been this way for a long time.
|
| [0]https://www.youtube.com/watch?v=d0SCf0rxX4E
| jedberg wrote:
| I wonder if it would be feasible for a neighborhood to get
| together and get one of these for everyone to share. In theory
| 1MW powers about 400 homes. Or for a new development to put one
| in and tout "free electricity for 50 years" as benefit of the
| development.
|
| Or a condo complex getting one with their condo fees.
|
| So many possibilities.
| Gracana wrote:
| I can just imagine going to that HOA meeting:
|
| Here's the plan for the reactor installation. Does it look good
| to everyone?
|
| Yes.
|
| Okay, next item: What color shall we paint the bike shed?
| wmf wrote:
| No, you have to use up the whole meeting with the bike shed
| _then_ slip in the nuclear reactor at the very end.
| m463 wrote:
| You seem to have overlooked the refreshment expenses!
|
| _" The agenda included three items: approving the plans
| for the plant, discussing a new bicycle shed for employees,
| and the refreshment expenses of the Welfare Committee."_
|
| https://en.wikipedia.org/wiki/Wikipedia:Avoid_Parkinson%27s
| _...
| giantg2 wrote:
| Then send a mailer after the meeting about the increase in
| fee to cover the new reactor maintenance.
| lwhi wrote:
| Why do people not get as excited by the prospect of renewable
| energy?
| [deleted]
| mmaurizi wrote:
| This is a great model, because then the neighborhood can use
| the reactor waste-heat for district heating!
| drran wrote:
| And they can use it for hundreds of years! With time, every
| home can get it own waste reactor with waste heat for
| heating!
|
| Future is here, it just unevenly distributed.
| godelski wrote:
| Which is actually really important because heating and
| cooling are big contributors to climate that aren't as
| obvious as electricity and transportation.
| kube-system wrote:
| I think the more immediate use cases will be industrial. These
| sound like exactly the power requirements of a data center.
| godelski wrote:
| Combine it with the data centers being placed under water.
| Now you got a big heat sink too.
| pdoconnell wrote:
| There's actually interesting issues with how property paid for
| through mortgages are impacted by nuclear regulations. I recall
| something deep in my mortgage about how (I think) the nuclear
| regulatory control act placed restrictions on local use vis a
| vis nuclear energy.
| chigbo wrote:
| Am new
| NiceWayToDoIT wrote:
| Anyone info about the price per MW, availability?
| dbetteridge wrote:
| So how many decades are we away from something like Naquadah
| generators?
|
| Is this something that is even possible with our current fuel
| sources or would it require some currently unavailable fuel.
|
| https://stargate.fandom.com/wiki/Naquadah_generator
| azernik wrote:
| Quite far - miniaturization of nuclear reactors is generally
| quite hard.
|
| We haven't put much effort into miniaturizing terrestrial
| reactors, and naval reactors have other design concerns which
| limit, but space reactors are a good gauge of the state of the
| art. From the (production!) American SNAP reactors of the 60s
| and the contemporary (production!) Soviet BES-5s, to the
| current Kilopower design studies and prototypes, there's been
| basically zero progress in reducing size. Fission has some hard
| floors on reactor (and bomb) size, because of the logic of
| criticality.
|
| That design floor for power reactors is quite large - the core
| itself is usually on the order of 50-75cm long by 20-30cm
| diameter, but the heat-to-electric conversion machinery and,
| more importantly shielding, will quadruple or quintuple that
| length.
|
| And that's with the cheats enabled by space applications, where
| you only need to shield in the direction of the spacecraft. For
| general use a similar design would fill a shipping container,
| like the linked microreactors tend to.
|
| Fusion is maybe a more plausible route to small power sources
| on the order of decades, because there's a clear parameter to
| tweak: magnetic field. Better superconductors -> stronger
| magnetic field -> smaller minimum size.
| 1970-01-01 wrote:
| See also Small modular reactor:
| https://en.wikipedia.org/wiki/Small_modular_reactor
| shadowgovt wrote:
| ... a miserable pile of secrets.
| mikewarot wrote:
| What if we socialized production of these, turned them out in
| quantity, to be owned and monitored by the Department of Energy,
| in order to increase national security.
| giantg2 wrote:
| How would that increase security?
| andrewljohnson wrote:
| I think the parent comment is saying we are dependent on
| foreign oil and this will alleviate that.
| TheAdamAndChe wrote:
| Not only that, but global warming is slated to destabilize
| many regions of the planet. The quicker we can move en
| masse away from oil, the less severe that transition will
| be.
| aeyes wrote:
| >95% of Uranium is imported as well
|
| https://www.eia.gov/energyexplained/nuclear/where-our-
| uraniu...
| nradov wrote:
| The US hasn't been dependent on foreign oil for years.
| ansible wrote:
| > _The US hasn 't been dependent on foreign oil for
| years._
|
| Years? No:
|
| https://www.eia.gov/energyexplained/oil-and-petroleum-
| produc...
|
| Last year, yes, for the first time since 1949. But even
| in 2020, we were importing more crude oil than we were
| exporting. The difference was due to the refined products
| that we exported.
| teclordphrack2 wrote:
| Hence the isolationism in some.
| hinkley wrote:
| Which is a terrible, terrible plan.
|
| "When goods do not cross borders then soldiers will."
|
| Trade keeps people from trying to take things, and when
| they take them, they prefer to take them off of corpses.
| Isolation leads to jealousy and we're already isolated
| enough.
| Gabriel_Martin wrote:
| Ah oil, the path to peace for so many countries! No but
| in all seriousness there certainly must be better goods
| to trade which could replace oil, if peace is the goal.
| ragona wrote:
| You're saying we should be in favor of fossil fuels
| because it will.. prevent war? Gotta imagine the Middle
| East might have some experience here with regards to the
| peace bringing properties of oil.
| hinkley wrote:
| I'm saying that by appealing to people's sense of
| ultimate self-reliance you are creating a monster.
| i_haz_rabies wrote:
| Dependence on imported energy would be a key factor in a
| South China Sea conflict. It was a driver of Japan's
| expansionism in WWII.
| ncmncm wrote:
| These could have been fielded at any time in the last three
| decades. That they haven't been may be a consequence that they
| offer relatively little scope for the wholly-legal institutional
| corruption that has driven nuke power construction throughout its
| lifetime in the US.
|
| When construction costs are allowed to balloon 4x-10x over quoted
| cost, the great bulk of that amounts to a conduit from the public
| purse to private pockets over a decade or more. Projects where
| that is possible out-compete projects, for backing, that merely
| promise normal value for money spent. We see this dynamic not
| just in nuke projects, but in urban transit tunnels, military and
| manned-space procurement, fusion research, and abortive bullet-
| train projects.
|
| That we do not see it in most current solar and wind power
| projects with, instead, costs plummeting well below anything than
| could ever be matched by nukes, may be a consequence of some
| combination of the projects' short terms, idealistic contractors,
| and dead-simple accounting. It will take decades to drive costs
| back up to where they will be good conduits for corruption. It
| remains to be seen whether hydrogen projects can be made to serve
| in such a role, but there is strong demand.
| sthnblllII wrote:
| > These compact reactors will
|
| > smaller design concepts will
|
| > Most designs will
|
| Sounds like these are goals not accomplishments.
| stuff4ben wrote:
| I for one would love a molten salt reactor in everyones backyard.
| https://www.forbes.com/sites/llewellynking/2020/10/13/new-de...
| Maybe a scaled down version that could be deployed in communities
| thereby decentralizing electrical generation and distribution.
| ChuckMcM wrote:
| I'm pretty excited about these. It takes nuclear in a new
| direction. What disappoints me though is that of the people doing
| this research that I've contacted, none of them are reaching out
| to the "other side" (things you would pump the heat into) here. A
| packaged closed cycle steam turbine system for electricity
| generation, for example, would be an excellent add-on here.
|
| The Navy has some great small turbine systems (although they
| typically use the ocean as a big thermal sink for their re
| condensers), and the folks who design geothermal plants could
| have a role here if they wanted, but so far not much work there
| that has appeared in the sources I tend to scan.
|
| As a result I'm concerned that these things with hit the market
| with no "shovel ready" plans to put them into production, and the
| lag between that and when you can put them in production will
| kill the reactor developers. I have seen it in other industries
| and it hurts to watch it unfold.
| sroussey wrote:
| https://www.radiantnuclear.com/
| ChuckMcM wrote:
| I like these guys but get annoyed at the 1kWH == 1 Typical
| House. While a case can be made that over a 24h period a
| house may consume 24kWh the fact is that "typical" houses
| burst to anywhere between 5kW and 10kW depending on
| appliances (AC + Freezer compressor + Oven baking a roast and
| boom you're at 10kW) As a result if you hook a thousand
| houses to a 1MW reactor you're going to get a crap ton of
| brownouts.
| lwhi wrote:
| I've just read through the comments, and can't really see
| anyone else making this point .. so I'm assuming it will be
| unpopular.
|
| Why is nuclear the silver bullet that will save us?
|
| Logically, renewable and storage on a microlevel seems to make
| more sense.
|
| --
|
| With nuclear .. no matter how advanced the tech is now, I can't
| see how we're not robbing Peter to pay back Paul.
|
| The waste will be around for longer than we are. We have no
| solution other than 'lock it up'.
|
| Accidents do -- and most like will -- happen. How will
| increasing the volume of reactors not increase this risk?
| godelski wrote:
| > Why is nuclear the silver bullet that will save us?
|
| I'm not sure many people make this argument. Although the
| people that do are very vocal. But they are wrong. The
| general consensus around nuclear is that it adds to the
| number of solutions we can use. Considering the inhomogeneous
| nature of climate and regions nuclear may have advantages in
| certain areas, whereas other areas it may be unnecessary.
| Anyone claiming "one size fits all" is just selling snake
| oil. Essentially the argument comes down to "why time one
| hand behind your back when trying to solve an extremely
| important and challenging problem?"
|
| As for waste, it isn't as big of a deal as you might think.
| Though this is more difficult to understand without an
| expertise in the subject matter. Mostly this is due to the
| complexity of understanding the different types of waste,
| amounts, and the vastly different levels of radiation in
| those waste products. Most of these conversations are akin to
| people talking about rocket science without knowing Newtonian
| mechanics. Just listen to the experts and see what they are
| saying. You're on HN, so I trust you can understand the
| nuance that scientists use, though I know that sometimes this
| can get confusing to the public. Like how "disagreement"
| isn't much of a disagreement but more quibbling over minor
| details.
| beders wrote:
| > As for waste, it isn't as big of a deal as you might
| think.
|
| If John Oliver dedicates a whole episode to that problem,
| it is kinda a big of a deal, isn't it?
|
| Leave it in the ground. WWS is sufficient to transform our
| energy systems.
| lwhi wrote:
| I can understand that technological improvements will have
| improved safety and efficiency.
|
| I definitely agree that we need a spread of technologies to
| provide for our energy need.
|
| I'm not convinced nuclear needs to be part of that solution
| though.
| godelski wrote:
| > I'm not convinced nuclear needs to be part of that
| solution though.
|
| That's cool. But just recognize that the scientific
| community disagrees. Though many have given up on even
| trying to push nuclear as being a minimal part due to
| these types of responses. I just want you to be aware of
| how your personal and non-expertise stance stands
| compared to the scientific community.
| belorn wrote:
| > Logically, renewable and storage on a microlevel seems to
| make more sense.
|
| For northern countries where wind is the primary renewable
| sources, there does not exist any clean storage that is
| currently deployed and getting investments. The current
| "storage" being combined with renewable are fossil fuels,
| primarily oil and gas. The subsidize for energy stability
| goes to fossil fuels, the investment for bigger reserve
| capacity goes to fossil fuels, the national energy plan here
| in Sweden as an example is fossil fuels for stability and
| renewable for cheap production.
|
| Lithium batteries as an example are great when the charge
| cycle and capacity is measured in hours, like for solar. It
| works, it is cost effective, and it helps reduce the
| dependency on fossil fuels. For wind you have charge cycles
| measured in weeks and capacity demand that can last months.
|
| There are a few experimental project (likely heavily
| subsidized, and none that I can find that operate on buying
| wind power and reselling it weeks later), but the flow of
| money goes very distinctly towards fossil fuels right now.
| Nuclear provide at least an working alternative, and the
| occasional accident is a much better future than the non-
| accidental climate change that is occurring right now.
|
| That said, I would prefer if we simple banned fossil fuels as
| a strategy to provide gird stability and forced the market to
| decide on storage vs nuclear.
| ChuckMcM wrote:
| > Why is nuclear the silver bullet that will save us?
|
| Because you can generate power without adding CO2 to the air,
| or other pollutants. It works 24/7/365 and it requires no new
| "science" to produce.
|
| However, the root of your question appears to me to be
| founded in some misconceptions you have about nuclear power.
| It isn't uncommon because the information in most popular
| press articles about nuclear power is over 50 years old.
|
| To put that in perspective, imagine arguing the utility of an
| electric car when your data point is gas at 30 cents a gallon
| (the price in 1965[1])?
|
| But to talk about nuclear power with current data about how
| you would design a power plant (and these are the new designs
| we're talking about), the risks of them leaking _any_
| radioactivity, and the risk to people should that radio
| activity leak and it makes our decision to keep building
| fossil fuel plants look pretty stupid. It really does turn
| the whole question on its head.
|
| Nuclear is demonstrably cleaner, safer, lower risk, and
| potentially lower cost (although how do you price the cost of
| destroying the planet right?) than any other baseload
| technology. It even surpasses hydroelectric in terms of
| externalized costs of habitat destruction.
|
| But I recognize that if you base your analysis on an idea
| that any new nuclear plant would be identical to the ones at
| Fukishima (built in 1967) or Chernoybl (built in 1972) it
| does seem odd that we would want more of that.
|
| [1] https://www.energy.gov/eere/vehicles/fact-888-august-31-2
| 015...
| lwhi wrote:
| I think it's foolish to think we have things 'right' now.
|
| In 1967, I'm pretty certain the engineers responsible
| thought they had it everything in order.
|
| I take the view we will always fuck up.
|
| With nuclear, the fuck up will always have larger, longer
| lasting consequences.
|
| --
|
| Edit:
|
| > Nuclear is demonstrably cleaner, safer, lower risk, and
| potentially lower cost (although how do you price the cost
| of destroying the planet right?) than any other baseload
| technology.
|
| I'd agree it's cleaner if we didn't have the waste problem.
|
| You're making a false equivalence. It's not a case of
| nuclear or fosil fuels. We have other options.
| ChuckMcM wrote:
| What I hear you saying is that you have no confidence
| that we can learn from experience, and that our
| understanding of the process of radio active decay, and
| the effect of radiation on humans is incomplete.
|
| If that is correct, then I'd Do you fly on airplanes?
| Have you compared the risks of flying in 1967 and the
| risks of flying today?
| lwhi wrote:
| I have a belief that human ingenuity will be able to
| generate truly clean power. If you believe that too, then
| this period of nuclear usage, is a transitory period.
|
| If this transitory period has the ability to create
| substances that will potentially cause bother to
| generations living in thousands of years time, I think
| that's a problem.
|
| Quite simply there are alternatives.
| ska wrote:
| > Logically, renewable and storage on a microlevel seems to
| make more sense.
|
| Only assuming technological advances are made that we can't
| count on. Current day we don't have storage solutions that
| will do it, and most micro stuff doesn't work well enough to
| meet current demand anyway....
| Ericson2314 wrote:
| The other replies handle the large issue now, but let me go
| point by point.
|
| > Why is nuclear the silver bullet that will save us?
|
| Not supposed to be that, as others said.
|
| > The waste will be around for longer than we are. We have no
| solution other than 'lock it up'.
|
| If we sacrifice a Cubic mile to save the planet that's a god
| trade. Paul is a lot bigger than Peter here.
|
| > Accidents do -- and most like will -- happen. How will
| increasing the volume of reactors not increase this risk?
|
| The Tsunami was far worse than the meltdown; I am afraid
| people's fear-memory often conflates the two. I'm willing to
| admit the official stats with Chernobyl might be a coverup,
| but still, tons of poor people around the globe get sick or
| die from perhaps-illegal fossil fuel pollution. It's not a
| worse coverup than environment justice issues in the US.
|
| The annoyance here among pro-nuclear people is that other
| thing's problems get to slip underneath the radar, but
| nuclear's don't.
|
| > storage
|
| Consider storage will require tons of lithium. The ecological
| damage from that mining will also be catastrophic, and the
| ecosystems might take as long to recover.
|
| I'm not saying we shouldn't do lithium-ion batteries. We have
| little choice we're going to need more. Same thing with
| nuclear. Same thing with not decommissioning dams as soon as
| we like.
|
| The fact is with all routes, avoiding ecological collapse
| will cause local environmental issues. What irks people is
| the singling out of nuclear, as if other things didn't have
| issues too, and other essential systems (like top soil)
| repair as slowly as some radioactive isotopes degrade.
| lwhi wrote:
| I saw a report that the reactor at Chernobyl is in danger
| of starting a new nuclear reaction [1]
|
| Fukushima is going to release the waste water into the sea
| [2]
|
| [1] https://www.newscientist.com/article/2277195-nuclear-
| reactio...
|
| [2] https://www.bbc.co.uk/news/world-asia-56728068
| Dylan16807 wrote:
| We have designs now that are vastly safer than Chernobyl.
|
| > Fukushima is going to release the waste water into the
| sea
|
| Why are you even bringing that up? They're going to
| filter out basically everything, and the released water
| will be completely safe.
|
| Anyone that complains about the trace amounts of tritium
| had better be thousands of times more upset at coal
| power.
| sparker72678 wrote:
| I think it's more akin to putting out a structure fire with
| water. You stop the immediate threat and save lives and
| _some_ property.
|
| And while some property damage will result because it's all
| getting soaked, it's still better to have something left than
| nothing, and while an un-burnable building would be nice, it
| doesn't exist yet.
| whatshisface wrote:
| Qualitatively, every choice is equal, because a qualitative
| argument can't distinguish between a big problem plus a small
| benefit and a big benefit plus a small problem.
| Quantitatively, you can make rational decisions. So, the
| answer to your questions are, " _how much_ will building more
| reactors increase the accident risk, " and " _how much_
| nuclear waste will be produced in the course of normal
| operation? "
| lwhi wrote:
| This is a good point, 'how much' is an important question.
|
| But then, it seems society sometimes make the decision to
| take somethings off the table entirely.
|
| I look at the accident at Fukushima, and earlier (when I
| was small child) Chernobyl and I can't help wondering
| whether some risks aren't worth taking when there are
| alternatives available.
|
| I'm sure risk analysis was taken seriously in Japan. Often
| we miss things, and the people answering 'how much', quite
| frankly get it wrong.
| parineum wrote:
| Many view fission as a stop gap to fusion. I also think the
| scale of nuclear waste is vastly over estimated by the
| general populace.
|
| Generally, it produces very little waste in terms of spent
| fuel[1] and much of that can be recycled. That does require
| building newer, modern reactors though.
|
| > The waste will be around for longer than we are. We have no
| solution other than 'lock it up'.
|
| This is another thing that people don't really understand.
| Radioactivity is viewed as a monolith in pop culture. There's
| a perception that a radioactive thing will kill you in
| thousands of years. In reality, the length of time that
| something is dangerous is inverse to how dangerous it is, ie,
| the longer it's radioactive, the less deadly it is (and vise
| versa). Plutonium-239, the long term radioactive byproduct
| (24,000 years) is not that deadly [2] compared to the much
| more radioactive cesium-137 and strontium-90 which both have
| a half life of around 30 years [3].
|
| 1. https://www.energy.gov/ne/articles/5-fast-facts-about-
| spent-... 2.
| https://en.wikipedia.org/wiki/Plutonium-239#Hazards 3.
| https://www.nrc.gov/reading-rm/doc-collections/fact-
| sheets/r...
| lwhi wrote:
| I think it's the fact that it's a stop gap that worries me
| the most.
|
| Imagine being alive in thousands of years, having to mind
| the 'very little waste' that stopgap produced.
|
| I think I'd consider the generations that produced it
| pretty negatively.
| lgats wrote:
| Would these types of systems not be great for drop-in
| replacements in natural gas electricity generation facilities?
| Much like natural gas can replace coal through a plant upgrade.
| semi-extrinsic wrote:
| OTOH, power generation from industrial waste heat is an
| increasingly hot topic these days. Whether steam turbine or
| organic Rankine cycle, finding something compatible in the 1-10
| MW scale should be quite straightforward.
| instagraham wrote:
| "Most designs will require fuel with a higher concentration of
| uranium-235 that's not currently used in today's reactors"
|
| The problem with making such tech mainstream is you'd need
| impossible levels of security to prevent even one store of such
| material from being stolen.
| Manuel_D wrote:
| What is the threat model for fuel theft? Weaponizing uranium
| requires enrichment well above even what maritime reactors use.
| Note that the difference between 90% enrichment and 99.9%
| enrichment isn't a factor of 1.1 difference, it's a two-order
| of magnitude difference - the remaining impurities need to be
| reduced by a factor of 100, each of those extra nines is
| another order of magnitude. And even if fuel does get enriched,
| it requires extensive nuclear physics research and engineering
| effort to produce a fission device. The only groups proven to
| be capable of this are state actors, which can set up their own
| enrichment facilities and have no real reason to steal uranium.
|
| An alternative threat model is not producing a bomb, but
| dumping radioactive waste in a populated area. While damaging,
| radiation is a relatively slow killer save for the most intense
| doses. The amount of damage that it would be able to inflict is
| minimal relative to the amount of effort requires to break into
| a nuclear facility and exfiltrate fuel. The question that
| should be asked is, does this present a larger potential for
| harm as compared to the same amount of effort put into
| conventional means of destruction (bombing buildings, shooting
| up crowded areas)?
| cryptonector wrote:
| Enriching HEU to weapons grade is trivial by comparison to
| enriching natural uranium to even just 20%. Really, the
| difference in effort needed is enormous. Yeah, you still need
| centrifuges, but you need many fewer centrifuges and many
| fewer passes.
|
| Also, you can make a bomb with uranium enriched to much less
| than weapons grade -- you'll just need a lot more of it
| compared to weapons grade uranium.
| Manuel_D wrote:
| > Enriching 90% uranium to weapons grade is trivial by
| comparison to enriching natural uranium to even just 20%
|
| Naturally occurring uranium is 99% U238, and 1% U235 (and
| some U234, but that's a trivial amount). 20% enrichment
| means that 80% of the fuel is U238. You only need to take
| out 1/5th of the U238. In order to weaponize uranium, U238
| concentration needs to be reduced to 10% or below. You need
| to take out about 90% of the U238. Sure, if you're staring
| with 20% enriched uranium you'll need a factor of 20 less
| input material. But that's not very significant, uranium
| isn't particularly expensive. The factor that's limited by
| centrifuge capability is the final enrichment purity.
| That's why one of the main things nuclear weapons
| inspectors look at are centrifuges.
|
| > Also, you can make a bomb with uranium enriched to much
| less than weapons grade -- you'll just need a lot more of
| it compared to 99% enriched uranium.
|
| No, you can't. The presence of too much U238 prohibits a
| runaway nuclear reaction regardless of the amount of
| uranium. You can get fission from lower enrichment, but not
| runaway fission. It's like flare versus a firecracker. And
| that's a desirable trait in electric power generation. The
| main principle of weapons inspection is to ensure that a
| country's enrichment facilities can only enrich uranium to
| a purity sufficient for power generation, but below weapons
| applications. The height and diameter of the centrifuges
| are the main factors here.
| doikor wrote:
| Some of the designs are not made to be refueled. In those the
| fuel gets loaded in at the factory and sealed up. Though in
| that case they are loaded up with quite a large amount of fuel
| (like a couple tons of plutonium for a ~30y lifespan)
|
| In such designs you really would only need high security at the
| factory as stealing fuel from a reactor that is not meant to be
| opened (you would have to cut into it) and that is on without
| someone noticing is really really hard.
|
| edit: Would also like to add that such designs are not actively
| being pursued anymore. The tradeoffs just are not worth it. We
| know how to securely transport fuel around so that is not that
| big of an issue really.
| helmsb wrote:
| I once heard that stealing nuclear material from a reactor
| design like this was akin to stealing a lit bar-b-bq grill by
| hand. Not impossible but not very easy or practical.
| dividedbyzero wrote:
| You do realize the lengths states like Iran are going to
| enrich enough Uranium for a few simple bombs? If this works
| as a shortcut, it doesn't have to be easy or practical. And
| besides, it might be a lot easier if you don't care whether
| the people cracking the thing open will survive the ordeal,
| or whether radioactivity gets released to the environment.
| BurningFrog wrote:
| If you mean it would be a suicide mission, those happen
| with some regularity.
| ttul wrote:
| Except that you need to survive in order to successfully
| steal the fuel. And you won't survive. QED
| nicoburns wrote:
| Not necessarily if you're part of a team.
| ttul wrote:
| That is dark.
| dividedbyzero wrote:
| It is, and it's standard practice. Suicide bombers are
| almost always part of a team that provides them with
| instructions and know-how, sometimes equipment and money,
| and first and foremost with a goal to die for. Also, lots
| of these attacks are part of a greater political scheme,
| and I would assume pretty much all attackers are aware of
| that. If your sacrifice means your side gets access to
| actual freaking atomic bombs, I mean, I could see that be
| pretty enticing.
|
| And if not there's always the option to make people do
| lethal things against their will. People have been sent
| to their deaths by the millions over the course of
| history, that's totally doable.
|
| IMO, dotting the landscape with such reactors is just
| asking for some state or other to take them and use them
| to leapfrog a lot of the effort required to build nuclear
| bombs.
| AtlasBarfed wrote:
| Or with thorium breeding, fuel input is not a big deal, since
| thorium is pretty much not dangerous.
| nradov wrote:
| That doesn't really reduce security requirements for the
| reactor itself. It just means you don't have to secure
| additional fuel in transit.
| MR4D wrote:
| I'd imagine that a big concrete bunker in the ground
| effectively burying this thing would probably be pretty
| good security. Taking a look at how nuclear missiles are in
| silos and having a variant of that approach. Not saying
| it's the best approach, just that it's should be fairly
| solvable.
|
| Then again, it is nuclear that we're talking about, so.....
| doikor wrote:
| How exactly are you going to steal the fuel from inside the
| reactor if it is running?
|
| Only option is to cut into the reactor (and thus destroy
| it). And now you have just cut a hole into a nuclear
| reactor that is ON and killed yourself (or triggered a
| whole bunch of safety features stopping the nuclear
| reaction and maybe not kill the attacker but for sure
| notified the authorities)
|
| Basically such a reactor is started once installed and
| never turned off until end of its lifetime.
| anarazel wrote:
| > And now you have just cut a hole into a nuclear reactor
| that is ON and killed yourself (or triggered a whole
| bunch of safety features stopping the nuclear reaction
| and maybe not kill the attacker but for sure notified the
| authorities)
|
| So somebody can strap a bunch of explosives to it and
| cause a good bit of quite radioactive material to spill
| (I don't mean a chain reaction, just the normal
| radioactive waste). You don't need to steal it if your
| goal is to have a dirty bomb.
| dTal wrote:
| That's certainly a concern - but if we're stipulating
| people with huge amounts of explosives and ill-will, they
| can probably also do a lot of damage without the nuclear
| reactor anyway.
| anarazel wrote:
| Why huge amounts? These reactors are supposed to fit on a
| semi truck (see e.g. the articles "infographic").
| Manuel_D wrote:
| The spill is contained within the containment facility. I
| guess they could use enough explosives to also breach the
| containment facility. But if they're capable of that,
| they probably have the means to do even more damage by
| targeting a skyscraper. Multiple orders of magnitude more
| people died in 9/11 than in Fukushima.
| anarazel wrote:
| We're talking microreactors here? There's no huge
| containment facility. They're not all that large.
| Manuel_D wrote:
| Right there's no _huge_ containment facility, but there
| 's still a concrete dome over the reactor isn't there?
|
| I'm still not seeing how our hypothetical terrorist
| A-team inflicts more damage by attacking a microreactor
| versus attacking a populated area directly.
| anarazel wrote:
| > Right there's no huge containment facility, but there's
| still a concrete dome over the reactor isn't there?
|
| I'm pretty sure these aren't intended to be used with a
| concrete dome or anything as substantial as that. Look at
| the pictures in the article, and some of the referenced
| benefits:
|
| Can be used for emergency response to help restore power
| to areas hit by natural disasters
|
| - "Can be quickly removed from sites and exchanged for
| new ones"
|
| - "Can be used for emergency response to help restore
| power to areas hit by natural disasters"
|
| That doesn't really mesh with needing to build a concrete
| dome on site.
| Manuel_D wrote:
| Or it can be installed underground, as the same website
| has proposed in other articles on small reactors:
| https://www.energy.gov/ne/articles/5-key-resilient-
| features-... It's a lot easier to dig a pit than build a
| giant 5 meter thick dome.
|
| Regardless, the point remains: the question that needs to
| be asked isn't "are these sites vulnerable to attack"
| it's "can an attacker inflict more damage here than
| through conventional means?"
| cryptonector wrote:
| You can have tamper sensors and a great deal of tamper
| resistance. Add canary pinging of a remote service and
| alerting and you can have an armed response team on site
| within minutes of any attempt to hack the thing.
| moralestapia wrote:
| >a couple tons of plutonium
|
| Is that a typo? tons?
| wincy wrote:
| Keep in mind that one cubic feet of plutonium weighs ~1200
| pounds.
|
| A basketball made of solid plutonium would weigh 300 pounds
| or so.
| ttul wrote:
| Two (metric) tonnes of plutonium takes up 100 liters of
| space, or about 3.5 cubic feet.
| PeterisP wrote:
| Probably not really. It's much less than normal reactors -
| e.g. the infamous Chernobyl 4th block had 217 tons of
| uranium fuel in it, so a couple tons = two orders of
| magnitude less.
| doikor wrote:
| Yes if it is supposed to run for 30 years.
|
| See the "Reactors with Lifetime Cores" section of
|
| https://www.nrc.gov/reading-rm/doc-
| collections/commission/sl...
| moralestapia wrote:
| Thanks, I had no idea they consumed that much.
|
| The ref. is for 200MWe so I'd guess that for 1-5MW it
| would be less but no idea if it scales linearly.
|
| Also, could you load all the fuel at once and leave it
| running? Or would you have to refuel every n years?
| ska wrote:
| > Also, could you load all the fuel at once and leave it
| running?
|
| Some designs call for exactly this. After all it's heavy,
| so the volume isn't much.
| phendrenad2 wrote:
| My thought is, 30 years isn't enough. In 30 years you need to
| open the reactor and swap out the fuel, which is too tricky
| an operation (securing the fuel going in & out) to do cheaply
| and at scale. 30 years is within the lifetime of most people,
| so people are hesitant to cause a problem that they'll have
| to deal with. If these things can be buried in lead &
| concrete for 60+ years then maybe it'll happen.
| cryptonector wrote:
| If it pays for itself and then some then in 30 years you
| _recycle_ the used reactors and replace them with new ones.
|
| Recycling would mean sending the spent reactor back to the
| manufacturer who would have the tooling and skilled labor
| needed to safely open the reactor and extract the spent
| fuel (and then dispose of it safely).
| pjscott wrote:
| The micro-reactor designs I looked up generally fell into one
| of three categories:
|
| 1. Very high enrichment fuel because they need fast load-
| following, e.g. for naval use.
|
| 2. Very high enrichment fuel because they're for use in space,
| and lower mass is better.
|
| 3. Reactors for ordinary power use, with fuel that's enriched
| more than most, but still nowhere near enough to be practically
| useful for weapons.
|
| An example of #3 is the Westinghouse eVinci micro-reactor,
| which uses fuel enriched to a little under 20% U-235. Weapons-
| grade uranium is closer to 90%.
| nonameiguess wrote:
| Could make a dirty bomb still, but the risk from those is
| more psychological than real, which is probably why no one
| has ever tried to do it.
| drran wrote:
| s/no one/very few/
|
| https://time.com/4728293/uranium-underworld-dark-secrets-
| dir...
| godelski wrote:
| People often confuse the difference in enrichment needed for
| weapons and reactors. Typically a reactor is 3% where a
| weapon is 97%. It becomes significantly harder to create that
| much enriched uranium which is why experts call Iran's
| production a bluff. Past their agreed levels, but nowhere
| near enough for weapons. The whole Iran deal relies on this
| fact actually.
| rocqua wrote:
| Are they hinting at e.g. the option of using these for a similar
| blackout to the recent Texas one. Just ship in as many of these
| "on demand" and handle momentary demand spikes.
| ceejayoz wrote:
| The infographic indicates the installation turnaround as
| weeks/months, so it wouldn't work in those scenarios.
| NortySpock wrote:
| An adequate on-site water supply to boil for the turbine is
| probably going to the limiting factor for "mobile microreactor"
| designs
| metalman wrote:
| Hydro power runs on water,best if its not all full of radiation
| so you can drink it. Wind power runs on air,be nice if it was a
| lot cleaner for breathing purposes and real bad if it was all
| nuked up. Solar power runs on light of a bright sunshiny
| day,unlike nukes with that deadly glow in the dark Nuklear
| scnooklear go away.
| ska wrote:
| Hydro power runs only where there is enough water moving. Wind
| power runs only when there is enough wind. Solar power runs
| only when it's sunny enough, and never at night.
|
| Batteries are not nearly good enough to smooth this out.
|
| So ... all these things are great, but not enough to replace
| fossils practically at current tech.
| NortySpock wrote:
| "1-20 megawatts of thermal energy"
|
| Large reactors are usually 4GW thermal power converting to 1 GW
| electric, so you're going to get, I don't know, 10%-25%
| electrical conversion efficiency out of this, so 0.1MW to 5MW of
| electrical power.
|
| On the plus side you can probably dual-use this to run communal
| home heating systems, maybe even hot water.
|
| It'd be great for cold-climate towns (or space-colony
| applications) provided you can get some funding together.
| ChuckMcM wrote:
| Hey we know what is going to be the hot product to buy for
| bitcoin miners :-)
|
| I was thinking about data centers (20 - 50MW) and a "farm" of
| them to provide N+1 redundancy would be an interesting thing.
| 99% carbon neutral as well.
| endymi0n wrote:
| ...which plays in the same league as any large and modern wind
| turbine.
|
| Minus the proliferation risk of somebody stealing this
| comparatively small reactor and builds a dirty bomb with it -
| oh, and you still have to dismantle it and store safely for
| millenia after use.
|
| No, thanks... looks to me like nuclear is dead in the water.
| ArkanExplorer wrote:
| A wind turbine doesn't spin 24/7. You'd need a Wind Turbine +
| a very large battery.
|
| The waste heat from a mini nuke is also perfect for district
| heating.
| imtringued wrote:
| Nuclear is perfect for district heating. Thermal power
| plants have poor efficiency because of the need to convert
| thermal energy into electricity. You basically get a whole
| load of waste heat. If you do need the waste heat then you
| can't beat thermal power plants.
| ChildOfEru wrote:
| There are alternatives to batteries.
| https://en.wikipedia.org/wiki/Grid_energy_storage
|
| https://en.wikipedia.org/wiki/Thermal_energy_storage
|
| https://www.greentechmedia.com/articles/read/first-grid-
| scal...
| throwaway894345 wrote:
| > Minus the proliferation risk of somebody stealing this
| comparatively small reactor and builds a dirty bomb with it -
| oh, and you still have to dismantle it and store safely for
| millenia after use. No, thanks... looks to me like nuclear is
| dead in the water.
|
| The proliferation risk seems like a valid concern, but that
| we have to store radioactive material for millennia isn't a
| valid criticism of nuclear in general because we already have
| to store nuclear material and the costs associated with
| storing _more_ waste are marginal (if you can safely store a
| little nuclear waste then you can safely store a lot of it).
| baybal2 wrote:
| Proliferation risk is not a real concern.
|
| Norko, and Israel are best evidence.
| throwaway894345 wrote:
| My only point was that I'm willing to accept the argument
| that it's more difficult to secure more, smaller
| reactors.
| zackees wrote:
| > minus the proliferation risk of somebody stealing this
| comparatively small reactor and builds a dirty bomb with it
|
| Using that logic, we should stop production of ammonia
| fertilizer.
|
| > and you still have to dismantle it and store safely for
| millenia after use.
|
| The fact is that the entire worlds nuclear waste can be
| contained in about one swimming pool, which can be placed in
| the middle of a mountain or some other geologically stable
| area. You can't say that about coal, or wind (junk turbines
| that can't be recycled), or solar. The death rate per
| terawatt-hour of generated nuclear is far less than any other
| fuel source.
|
| The idea that Nuclear is a dead end has been made popular by
| pop culture from the 1970's and bad science driven by an
| agenda to keep everyone on a globalized fossil fuel monopoly
| run by the military industrial complex.
|
| Deaths per terawatt-hours comparison chart:
| https://www.statista.com/statistics/494425/death-rate-
| worldw...
| orlovs wrote:
| I consider Nuclear fission as necessary evil as we don't
| have other so efficient and same time devastating energy
| source. However, we as a human kind have left this
| technology not developed as much as we could from
| efficiency and safety point of view. With my youtube degree
| in nuclear physics I would say we are somewhere where
| internal combustion engines were in 1930ties.
| chinchilla2020 wrote:
| Curious if you have a source for the swimming pool metric
| rthomas6 wrote:
| This goes along with the coronal mass ejection risk story that
| was on the front page a day or two ago. Is a nationwide electric
| grid even a good idea anymore? Yes, it's more efficient, but it's
| also more fragile, in that a failure in critical infrastructure
| can cause nationwide blackouts.
|
| Imagine if most places had a microreactor, a small fossil fuel
| generator, renewable + storage, or some combination of these, and
| each small to medium sized community of homes had their own.
| Things would go wrong all the time on the small scale, but there
| would be no such thing as a nationwide blackout.
| notJim wrote:
| This is interesting, because usually I see nationwide grids
| being touted as MORE resilient, not less. The idea is if power
| is knocked out in one area, you can still get it from
| elsewhere. This came up a lot during the Texas situation.
| rthomas6 wrote:
| Texas is what I would still consider a "nationwide" power
| grid. I was thinking of something very very decentralized,
| like individual neighborhoods. It wouldn't completely solve
| what happened in Texas, but blackouts would be contained to
| small areas for hopefully shorter amounts of time, as failure
| in one area would have no effect on other areas, and
| individual neighborhoods could probably coordinate and
| conserve power usage as needed better than an entire state.
| godelski wrote:
| I think there's a balance. You want a slight surplus in your
| local area and connected so you can pump it somewhere else
| when that somewhere else goes down. Though IIRC Texas has far
| more problems than just not being connected (also far more
| than just renewables either, which was a big talking point).
| wmf wrote:
| Smaller grids like Texas are more susceptible to weather events
| though.
| Terr_ wrote:
| IANAElectrician, but IIRC the biggest problem isn't the grid
| size per se, but how grid operation requires always matching
| the amount of power coming from all producers and the amount
| being used by all consumers. Like a tightly-sealed water-pipe
| system where the pressure is uniform throughout, and too much
| pressure pops things, while too little won't go anywhere.
|
| So it's a coordination problem, and ideally you'd have a big-
| grid which can be arbitrarily partitioned (and recombined) to
| ensure producer-consumer matching as you get more and more of
| each involved again.
|
| It's one of the few cases where the phrase "smart home" doesn't
| make me cringe: Imagine a neighborhood of houses in a brownout
| situation all coordinating to dim the lights and space out
| their high-energy usage, like running refrigerator compressors.
| thereare5lights wrote:
| Are there examples of how a failure at a power plant could
| affect the national grid?
|
| As mentioned by another comment, one advantage of a national
| power grid is the ability to transfer power from other places
| during power failures. But I'm not sure how a power failure
| would affect the rest of the grid.
| akiselev wrote:
| _> Are there examples of how a failure at a power plant could
| affect the national grid?_
|
| A failure at any single power plant is very unlikely to cause
| cascading failures in the rest of the grid because one power
| plant usually can't generate enough power relative to its
| grid.
|
| Gross oversimplification but all of the power plants in a
| national grid are essentially coupled together [1] as a giant
| circuit made up of a ton of electromagnets - the generators
| converting coal/natgas powered steam or water/wind to
| electricity. These electromagnets are all operating at the
| same frequency in phase with each other which literally means
| that the generators spin in sync at ~60hz. These generators
| are often (usually?) heavy turbines with a lot of angular
| momentum so normally when you connect a power plant, it stays
| in phase just due to the sheer inertia of the rest of the
| grid because power follows phase [2].
|
| When the phase changes suddenly - like when connecting a
| generator that is out of phase with the grid - all that
| inertia of the generator essentially slams into the
| electromagnetic force generated by the incoming current. If
| the rest of the grid (of hundreds/thousands of other
| generators) produces significantly more power, it'll just
| destroy the connecting one as if you brought a turbine
| powered jet engine to an instantaneous dead stop - the
| momentum of the blades will literally rip them off of the
| shaft. However, if the newly connected generators are
| producing a significant amount of power relative to the rest
| of the grid, like when a corona mass ejection hits or a large
| islanded subgrid is poorly reconnected, the resulting
| differential can generate a wave (again, gross
| simplification) that travels through the grid with enough
| power to destroy every single generator connected to it.
|
| A single power plant just can't generate enough power to do
| damage to the rest of the grid [3] but if a natural disaster
| severed the connection between two regions of a grid and they
| drift out of phase, they must be carefully reconnected
| because they might have enough power to seriously damage
| other power plants.
|
| [1] Some parts of a grid might be separated by HVDC which in
| effect isolates the parts
|
| [2] Power flows from the faster generators to the slower
| ones, speeding them up until they hit equilibrium.
|
| [3] There are exceptions depending on grid topology, but
| generally grids are designed to avoid them
| epistasis wrote:
| A better national grid for renewables will be hugely redundant,
| with few single points of failure, because renewables are
| distributed throughout geography.
|
| If something takes out that sort of infrastructure, it's
| probably going to take out the local micro reactor too.
|
| Existing solutions for micro grids are getting super cheap too,
| if we didn't already have tons of transmission built out,
| starting a grid from scratch today would probably include not
| only far less transmission, but far more storage, which also
| hugely increases resiliency.
|
| Having tons of storage and solar right behind the meter, by
| which I mean 10%-40% of buildings, would hugely increase the
| resiliency of the grid, if utilities would embrace the
| Information Age build bottom-up infrastructure in addition to
| top-down.
___________________________________________________________________
(page generated 2021-05-12 23:02 UTC)