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If you have to deal with radioactive materials, why not just use fission? Fundamentally: fission fuels are limited, particularly uranium. If humans were to r

If 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>.

scottshamus 2y ago
I was curious about your point that we only have ~20 years supply. The article you linked doesn’t really defend that estimate, I think it’s actually pointing out that’s the absolute floor of our supply. It mentions estimates of undiscovered uranium and also multiple pathways to extend that estimate if there was demand to improve the technology or increase our supply. It sounds like realistically we could find the material for powering all of our energy using fission if we had the demand to do so.
- wokwokwok 2y ago
  If you want to speculate wildly on maybes then it’s also hard to argue that hydrogen is fundamentally one of the most common elements in the entire universe and it’s not particularly controversial to say that a high tech future society would probably want to use that rather than the vastly less abundant heavier elements. > It sounds like realistically we could find the material for powering all of our energy using fission For a while > if we had the demand to do so. Maybe two decades isn’t spot on, but come on, you’re really grasping at straws. It’s fundamentally less abundant. 20 years? 50 years? 100 years. Sooner or later you’re going to run out, and not on geological timescales. Tell me it ain’t so? There are reasons to prefer fission, but “we have plenty of uranium” isn’t one of them.
- dredmorbius 2y ago
  The resource size is one I've seen many times in many places, and it seems widely accepted. The linked article isn't the best source, but it's characteristics of others I've encountered over the years. The general point is that uranium ore is not especially abundant, and tends to be highly localised, which suggests a reprise of petroleum-induced geopolitics. (Uranium in seawater is far more prevalent, but quite difficult and expensive to access.) I'm also familiar with the long and tedious discussion of just what "resources" and "reserves" constitute. I'd suggest briefly that much of that discussion fails to reflect that the true benefit of energy resources is the surplus EROEI (energy return on energy input) which results from their use, and that whilst it's often possible to increase the total resource quantity that comes with a corresponding decrease in resource quality in the sense of a far lower EROEI. Early petroleum finds featured EROEI of 200:1 or greater. That is, 1 unit of energy invested returned 200 units returned. Present finds are closer to 10:1 to 20:1. I'm not as versed on uranium, though I'm finding indications that current ore-based finds are ~10:1 to 60:1. Seawater extraction is all but certainly far lower than that. Generally I'm somewhat suspicious of casual claims that we could vastly increase our uranium supply. Thorium's a somewhat different animal (or mineral, definitely not vegetable) in that it's 3--4 times more abundant than uranium, and if I recall correctly can be "bred" into fissionable forms more readily. Non-thorium breeder reactors rely on a plutonium cycle, which introduces numerous other concerns (weapons, terrorism, etc.). Moreover, liquid hydrocarbon is fantastically useful stuff and can be stored, transported, and utilised with immense flexibility and (comparative) safety. Nuclear energy must be converted to other forms, at considerable loss, to be utilised. Grid mains current is useful, but nuclear power plant output isn't especially flexible, and transition to storable forms comes at high costs, limited capacity, or high conversion losses (e.g., synfuel production). Hydrocarbon-powered automobiles, lorries, aircraft, construction equipment, hand tools, portable generators, etc., are all readily produced and utilised. Their nuclear variants not so much. (I'm specifying hydrocarbons rather than petroleum to note that it's the chemical constitution rather than the origin or creation process which is significant here. I'm something of a fan of hydrocarbon fuels, somewhat less so of fossil fuels, despite their past utility.)

scottshamus 2y ago

I was curious about your point that we only have ~20 years supply. The article you linked doesn’t really defend that estimate, I think it’s actually pointing out that’s the absolute floor of our supply. It mentions estimates of undiscovered uranium and also multiple pathways to extend that estimate if there was demand to improve the technology or increase our supply. It sounds like realistically we could find the material for powering all of our energy using fission if we had the demand to do so.

wokwokwok 2y ago
If you want to speculate wildly on maybes then it’s also hard to argue that hydrogen is fundamentally one of the most common elements in the entire universe and it’s not particularly controversial to say that a high tech future society would probably want to use that rather than the vastly less abundant heavier elements. > It sounds like realistically we could find the material for powering all of our energy using fission For a while > if we had the demand to do so. Maybe two decades isn’t spot on, but come on, you’re really grasping at straws. It’s fundamentally less abundant. 20 years? 50 years? 100 years. Sooner or later you’re going to run out, and not on geological timescales. Tell me it ain’t so? There are reasons to prefer fission, but “we have plenty of uranium” isn’t one of them.
dredmorbius 2y ago
The resource size is one I've seen many times in many places, and it seems widely accepted. The linked article isn't the best source, but it's characteristics of others I've encountered over the years. The general point is that uranium ore is not especially abundant, and tends to be highly localised, which suggests a reprise of petroleum-induced geopolitics. (Uranium in seawater is far more prevalent, but quite difficult and expensive to access.) I'm also familiar with the long and tedious discussion of just what "resources" and "reserves" constitute. I'd suggest briefly that much of that discussion fails to reflect that the true benefit of energy resources is the surplus EROEI (energy return on energy input) which results from their use, and that whilst it's often possible to increase the total resource quantity that comes with a corresponding decrease in resource quality in the sense of a far lower EROEI. Early petroleum finds featured EROEI of 200:1 or greater. That is, 1 unit of energy invested returned 200 units returned. Present finds are closer to 10:1 to 20:1. I'm not as versed on uranium, though I'm finding indications that current ore-based finds are ~10:1 to 60:1. Seawater extraction is all but certainly far lower than that. Generally I'm somewhat suspicious of casual claims that we could vastly increase our uranium supply. Thorium's a somewhat different animal (or mineral, definitely not vegetable) in that it's 3--4 times more abundant than uranium, and if I recall correctly can be "bred" into fissionable forms more readily. Non-thorium breeder reactors rely on a plutonium cycle, which introduces numerous other concerns (weapons, terrorism, etc.). Moreover, liquid hydrocarbon is fantastically useful stuff and can be stored, transported, and utilised with immense flexibility and (comparative) safety. Nuclear energy must be converted to other forms, at considerable loss, to be utilised. Grid mains current is useful, but nuclear power plant output isn't especially flexible, and transition to storable forms comes at high costs, limited capacity, or high conversion losses (e.g., synfuel production). Hydrocarbon-powered automobiles, lorries, aircraft, construction equipment, hand tools, portable generators, etc., are all readily produced and utilised. Their nuclear variants not so much. (I'm specifying hydrocarbons rather than petroleum to note that it's the chemical constitution rather than the origin or creation process which is significant here. I'm something of a fan of hydrocarbon fuels, somewhat less so of fossil fuels, despite their past utility.)