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Piece of a fission reactor became radioactive due to neutron bombardment. Lost track of this radioactive piece in the pool, found it by accident, zap! Neutron
by atomic128 2y ago
Piece of a fission reactor became radioactive due to neutron bombardment.
Lost track of this radioactive piece in the pool, found it by accident, zap!
Neutrons make hardware radioactive.
Many on Hacker News fantasize about fusion (not fission) reactors. These fusion (not fission) reactors will be an intense source of fast neutrons. All the hardware in a fusion (not fission) reactor will become radioactive. Not to mention the gamma rays.
If you have to deal with radioactive materials, why not just use fission? After 70 years of working with fission reactors, we know how to build and operate them at 95%+ efficiency. Fission can provide all the power we will need in our lifetimes.
Quoting John Carmack: "Deuterium fusion would give us a cheap and basically unlimited fuel source with a modest waste stream, but it is an almost comically complex and expensive way to generate heat compared to fission, which is basically 'put these rocks next to each other and they get hot'."
- LargoLasskhyfv 2y agoButt whaddäbbaut https://en.wikipedia.org/wiki/Aneutronic_fusion https://en.wikipedia.org/wiki/Aneutronic_fusion ?
- jiggawatts 2y agoI assume you're joking, but for others who might not realise: aneutronic fusion is mostly aneutronic, not entirely. Some neutrons are still released, and the reactor walls will still become radioactive over time, just slower. Oh, and also, the fuel types that do produce a usefully lower level of neutron radiation are absurdly hard to get to fuse. We're talking 100x harder than the "easy" D-T fusion... which in turn is five decades of technology development away from producing useful amounts of power. Aneutronic fusion reactors will be used on interstellar craft... in the 2100s. See the "residual radiation" section in the same article: https://en.wikipedia.org/wiki/Aneutronic_fusion#Residual_radiation https://en.wikipedia.org/wiki/Aneutronic_fusion#Residual_rad...
- LargoLasskhyfv 2y agoHmmmm. Then let's try https://en.wikipedia.org/wiki/Gaseous_fission_reactor https://en.wikipedia.org/wiki/Gaseous_fission_reactor instead!1!! :)
- fragmede 2y agoFission radioactivity is the bad stuff that will be radioactive for millions of years and we don't know how deal with that. It needs heavy metals like plutonium and uranium and when it goes wrong, they melt down and we all have a bad time. Fusion uses tritium and can be made from seawater and makes helium, and doesn't melt down in the same way, and the waste is relatively short lived.
- atomic128 2y agoSee discussion of dry cask storage here: https://news.ycombinator.com/item?id=41601833 https://news.ycombinator.com/item?id=41601833
- pfdietz 2y agoDry cask storage is simple, relatively cheap, and forecloses no future option for dealing with waste. By the time the waste is so cooled off it is no longer self protecting from amateur diversion of plutonium -- maybe 300 years -- options should be greatly expanded for its disposal, including shooting it into space on dirt cheap extremely reliable launchers. In any case, setting the fuel disposal cost to zero still leaves fission uncompetitive, given the cost of building new nuclear power plants. This is especially the case if one imagines a nuclear powered world economy, which likely would have to resort to some flavor of breeder reactors. Reprocessing would be necessary for breeders, but that wouldn't make breeders cheaper than current burner reactors.
- roenxi 2y ago> Fission radioactivity is the bad stuff that will be radioactive for millions of years and we don't know how deal with that. We also don't know how to deal with lead and it will be poisonous until we figure out how to biologically re-engineer the human species. So far so good, we still use lead, you can buy the stuff by the kilo. This is a minor problem to the point where the people bringing it up aren't taking the situation seriously. The volumes are tiny and we can just dump it somewhere.
- alex_young 2y ago
- boringg 2y agoI find it funny that you speak about nuclear energy yet you validate it based on a quote from an exceptional game designer. This isn’t a knock on Carmack but more like you should probably hunt for someone in discipline, there are many.
- whimsicalism 2y agogeneralists are underrated nowadays it seems, compared to most of scientific history where they very clearly exist and can make contributions across a ton of “disciplines”
- xattt 2y agoGeneralists and specialists veering out of their lane come across the same until there is an incorrect statement about a field you know.
- graemep 2y agoInformed generalists might also be a useful perspective to a field, or bring in relevant knowledge not well known within the field.
- whimsicalism 2y agoThere are any number of cases of “specialists” having arrived at some incorrect consensus due to social factors/groupthink and a failure of the process.
- edem 2y agoCarmack is not a game designer (never was in fact). Carmack is a God. Also, jist because what you think he is doesn't mean that he is not right.
- junon 2y agoLet's not normalize placing people who do cool things on unnecessarily large pedestals. Idolization like that never has a good outcome.
- dredmorbius 2y agoIf you have to deal with radioactive materials, why not just use fission? Fundamentally: fission fuels are limited, particularly uranium. If humans were to run current energy demands 100% on uranium-based nuclear power, we'd burn through reserves in about two decades.[1] Breeder reactors and thorium fusion change that calculus, as might viable uranium recovery from seawater. (Uranium, unlike thorium, dissolves in seawater, though the quantities of water which would have to be processed would be absolutely immense and nontrivial on multiple grounds.) Fusion is based on hydrogen and a few other light elements, which are vastly more prevalent, most notably as water found on Earth (and elsewhere in the solar system should we use so much hydrogen that net water prevalence is affected). The slight hitch in the scheme is that whilst fission is so simple an untrained janitor can achieve it,[2] or even plain old dumb rocks,[3] fusion turns out to be fiendishly difficult on Earth / at terrestrial conditions. ________________________________ Notes: 1. Based on a 200 year supply at ~10% of total energy supply presently, which scales to ~20 years at 100%: <https://www.scientificamerican.com/article/how-long-will-global-uranium-deposits-last/ https://www.scientificamerican.com/article/how-long-will-glo...>. 2. For example: Oak Ridge prodcedures / Feyman (~1945) <https://robertlovespi.net/2014/09/07/how-richard-feynman-saved-eastern-tennessee-from-getting-nuked/ https://robertlovespi.net/2014/09/07/how-richard-feynman-sav...>, Cecil Kelley (1958) <https://en.wikipedia.org/wiki/Cecil_Kelley_criticality_accident https://en.wikipedia.org/wiki/Cecil_Kelley_criticality_accid...>, Y-12 plant (1958) <https://en.wikipedia.org/wiki/Y-12_National_Security_Complex#1958_criticality_incident https://en.wikipedia.org/wiki/Y-12_National_Security_Complex...>, Vinča Nuclear Institute (1958) <https://en.wikipedia.org/wiki/Vin%C4%8Da_Nuclear_Institute#1958_reactor_incident https://en.wikipedia.org/wiki/Vin%C4%8Da_Nuclear_Institute#1...>, Wood River Junction (1964) <https://en.wikipedia.org/wiki/Wood_River_Junction,_Rhode_Island#Criticality_accident https://en.wikipedia.org/wiki/Wood_River_Junction,_Rhode_Isl...>, Mayak (1968) <https://en.wikipedia.org/wiki/Mayak#1968_Criticality_Incident https://en.wikipedia.org/wiki/Mayak#1968_Criticality_Inciden...>, and Tokaimura (1997) <https://en.wikipedia.org/wiki/Tokaimura_nuclear_accidents https://en.wikipedia.org/wiki/Tokaimura_nuclear_accidents> being just a few. Wikipedia has a more comprehensive listing: <https://en.wikipedia.org/wiki/Criticality_accident#Known_incidents https://en.wikipedia.org/wiki/Criticality_accident#Known_inc...>. My point isn't that the perpetrators were necessarily janitors, or untrained (though some effectively were), but that criticality was achieved entirely unintentionally. Accidental fusion criticality incidents are far less frequent. 3. "Natural fission reactors" are a thing: <https://en.wikipedia.org/wiki/Natural_nuclear_fission_reactor#Discovery_of_the_Oklo_fossil_reactors https://en.wikipedia.org/wiki/Natural_nuclear_fission_reacto...>. To be fair, so are natural fusion reactors, though few have yet been discovered on Earth: <https://en.wikipedia.org/wiki/Star https://en.wikipedia.org/wiki/Star>.
- fdfgyu 2y agoThere's radioactive and there's radioactive. With a neutron source we can control what the isotopes will be by choosing the appropriate metals for construction. In fission you get, more or less, all the isotopes you can. fission doesn't split U235 into the same parts every time - its a random process and broad distribution of daughter fission isotopes are produced. But I still agree. We should go with breeder reactors and call it a day
- physicsguy 2y agoIt’s actually really hard, the atoms you normally dope steel with on absorbing neutrons become really quite nasty isotopes. I went to a talk on this a few years ago from a materials scientist at Culham and he was saying while the physics might be getting closer, choosing appropriate vessels is really hard and the expected life of them at the moment is under 5 years which wouldn’t be viable for a commercial reactor running full time. Helium bubbles can form within the steel along grain boundaries, causing it fracture.
- fdfgyu 2y agoI know ;)
- minetest2048 2y ago> If you have to deal with radioactive materials, why not just use fission? One of the reasons is that we can make nuclear bombs out of it. People currently value not getting nuked more than clean and unlimited fission energy, so everything that might be used to make nukes are insanely regulated. This have downstream effects that make nuclear fission hard and expensive: - With renewable energy power plants, you can use normal security. With nuclear fusion power plants, stealing a big tokamak wall to make dirty bomb is hard, so you can still use normal security. With fission power plants you need special armed security - You need to provide accountability to IAEA to prove that you don't smuggle those plutonium away to make nukes. This affects the nuclear power plant design, as you don't want to have any blind spot where the operator can smuggle the nuclear material away: https://www.youtube.com/watch?v=_HHMAht3gSg https://www.youtube.com/watch?v=_HHMAht3gSg - Some countries ban nuclear waste reprocessing because they don't want someone using the plutonium from reprocessing process to make nukes. This is really sad as they're throwing all the good fuel away from the waste. Similar story with breeder reactors With meltdown risk at least its solvable by safer reactor design, but there's no way we can remove those expensive safeguards.
- chickenbig 2y ago> One of the reasons is that we can make nuclear bombs out of it. Are you talking about a dirty bomb? Spent nuclear fuel from PWR/BWR do not contain the right isotopes of Plutonium. https://en.wikipedia.org/wiki/Reactor-grade_plutonium https://en.wikipedia.org/wiki/Reactor-grade_plutonium > People currently value not getting nuked more than clean and unlimited fission energy This looks like a false-choice. A choice between the presence of nuclear weapons vs unlimited fission energy might be slightly fairer, but many countries have a civil nuclear program without nuclear weapons. > With renewable energy power plants, you can use normal security Non-"normal security" is not a great cost for a nuclear power station (1+ GW). 50 extra staff might be 5M USD a year extra, so 0.60 USD/MWh more. Scaling to more reactors per site would give economies of scale. > You need to provide accountability to IAEA to prove that you don't smuggle those plutonium away to make nukes. Accountability is good; tracking where each fuel bundle is and goes is fairly standard practice (at least nowadays), no? Audits don't have to be a pain if their requirements mesh with the business processes. > This is really sad as they're throwing all the good fuel away from the waste. The Plutonium is good stuff for breeder reactors. The depleted Uranium bulk is less useful, as we have thousands of tonnes already sitting around. Perhaps the most interesting aspect of reprocessing is the extraction and vitrification of fission products. Less bulk, splitting the higher activity products out of the bulk, reducing the storage requirements. > there's no way we can remove those expensive safeguards Rules can be changed. De-escalation is possible!
- pfdietz 2y agoThe question really isn't "why not use fission", it's "why should fusion not be more expensive than fission"? Since fission is losing because it's too expensive, any other advantage of fusion over fission means little if it's even more expensive.
- rnhmjoj 2y agoI don't think fission is loosing because it's too expensive: it has acquired a reputation of being dangerous and it's probably too late to convience people otherwise, maybe younger generations. Fusion is kind of unknown to the larger public and is still described as the magical unlimited power source and safe alternative to fission, so it still has a chance.
- pfdietz 2y agoNo, it's because it's too expensive. The idea that fission is losing because of wrongthink is a comforting tale told by nuclear fans.
- rnhmjoj 2y agoComfort tale or not, my country banned it completely 40 years ago by popular referendum. I don't think the economics were what people had in mind one year after the Chernobyl disaster.
- pfdietz 2y agoCorrelation is not causation. You would need to show that in the absence of that ban, nuclear would have been successful. The "nuclear would have worked except for the meddling kids" theory needs to explain why all sorts of other destructive technologies plow right along, even in the face of massive campaigns against them. The distinguishing feature is those technologies are economic winners. Large profit flows trump activism. Unprofitable technologies don't have the stakeholders who would defend them.
- jaggederest 2y agoSame but why deal with anything reactive at all? The largest thing in our solar system is an already running fusion reactor that is already beaming 1.361 KW/m^2 to the planet.
- halper 2y agoThe kilo prefix is always written with a lowercase "k": kW for kilowatts.
- edem 2y agoEfficiency is the name of the game.
- TeMPOraL 2y agoBecause beamed energy is inefficient in many ways, including space used for collectors, and the damn thing is only working for at most half a day at any given location anyway? It's a bit of a "why invent wheels when cows already have legs" kind of question. (Also "why learn to do anything on your own when you have rich parents that provide?")
- hmcq6 2y agoWho cares that it's inefficient if it is orders of magnitude more electricity than we need?
- elcritch 2y agoBecause batteries are expensive but needed for overnight storage or cloudy conditions. There’s also the amount of land and materials needed to produce solar devices. It’s ultimately more about unit cost of power than total available power.
- hmcq6 2y agoCan we not build solar panels in the ocean like we do with wind turbines? "Because batteries are expensive" Are they? It would only take 4000 copies of the Moss Landing Energy Storage Facility to store all the electricity we currently use in a day. Some back of the napkin math says it would cost $2 Trillion, which is only double the amout we subsidized the fuel industry last year
- mmooss 2y ago> After 70 years of working with fission reactors, we know how to build and operate them at 95%+ efficiency. Fission can provide all the power we will need in our lifetimes. We still don't know how to build fission power plants cost-effectively. In the last week I saw an article saying that projects can't get financing in the marketplace. If we still don't after 70 years, it seems doubtful that it will work. If we can find a cheaper way - even if we could build fission plants cost-effectively now - we should probably do it?
- cycomanic 2y ago> Piece of a fission reactor became radioactive due to neutron bombardment. > Lost track of this radioactive piece in the pool, found it by accident, zap! > Neutrons make hardware radioactive. > Many on Hacker News fantasize about fusion (not fission) reactors. These fusion (not fission) reactors will be an intense source of fast neutrons. All the hardware in a fusion (not fission) reactor will become radioactive. Not to mention the gamma rays. > If you have to deal with radioactive materials, why not just use fission? After 70 years of working with fission reactors, we know how to build and operate them at 95%+ efficiency. Fission can provide all the power we will need in our lifetimes. What do you mean by 95% efficiency? Fission reactors are heat engines, their efficiency is much lower typical reactors are 35% while modern designs can reach up to 45%. That's the thermal efficiency, if we consider the energy stored inside the fission material it's much lower still.
- atomic128 2y agohttps://www.energy.gov/ne/articles/what-generation-capacity https://www.energy.gov/ne/articles/what-generation-capacity
- cycomanic 2y agoWhy when I ask you about efficiency are you linking to an article about capacity (and the capacity factor)? Apart from the fact that those two are two completely different measures, nuclear power plants also don't have capacity factors of 95% (80-85% is more typical).