Over-hyped BS. There are regular reactors, and there are breeder reactors (fast neutron reactors), both can use uranium but only the latter type can use thorium. The latter type, also, incidentally, uses a lot less uranium than the former, and can use depleted uranium. The cost of fuel is of no consequence and all the safety issues are virtually identical for fast neutron reactors using thorium and using uranium (and for both, are expected to be significantly more severe than for regular water moderated reactors) There’s a lot of depleted uranium laying around costing negative $ . Not thorium, though.
Pretty much, yeah. The hexafloride is somewhat harder to contain, though. And expect long-term brain damage from the block of lead.
(The decay chain of U-238 is mostly alpha and beta, which are completely absorbed by paper wrapping. There is some gamma radiation in some of the decay steps, but not significantly more than background for any reasonable amount. 18,500 metric tons of the stuff might have a total activity somewhat higher (=2.74e15 Bq), or one mole of helium produced every 70 years from direct decay alone, and a few mA’s worth of electron emissions once the decay products reach equilibrium. It looks like the half-thickness for ‘uranium’ is about 7mm for Co-60 gamma emissions.
Doing the calculus, the total unshielded activity at the surface of the block would be equal to the integral of (total activity per unit thickness {14.8 Bq/mg; DU has a density of 18.5 G/cc}*percentage unshielded at that depth)
*{(}1/2)}%5E{(1000x/7cM)}dx)
(1000cM^2 is the cross sectional area, 1000mG/G is a conversion factor, making the first term the total activity per thickness; second term is the percentage unshielded calculated by raising 1⁄2 to the power of the number of half thicknesses of uranium above the layer in question. X is in cM.)
Overall though, the stochastic effects of ionizing radiation exposure are close enough to zero that studies of the effects of occupational exposure do not find conclusive correlations of long term low-level exposure to disease.
And expect long-term brain damage from the block of lead.
I don’t believe you.
It’s wrapped in paper (your stipulation) and under the bed (my stipulation). Are you asserting that the wrapped, undisturbed block of counterfactual lead under my bed is a significant airborne pollution threat?
Overall though, the stochastic effects of ionizing radiation exposure are close enough to zero that studies of the effects of occupational exposure do not find conclusive correlations of long term low-level exposure to disease.
I wasn’t wrapping the lead in paper, but that wasn’t fair of me- because frankly, inhaled DU particles ARE much worse than inhaled lead particles, because the ‘wrapped in paper’ (or painted, I suppose) is significant. DU munitions and armor aren’t ‘safe’ in the sense of failing to contaminate the nearby area, but neither are lead munitions.
I’d be more concerned about the fire hazard if you scratch it (by your depleted uranium paperweight). It’s like lighter sparkler on steroids, from what i’ve heard. The activity in practice would also depend to how depleted it is (they don’t deplete all the way to 0% u-235), and it better not be “dirty” depleted uranium from fuel re-processing. edit: also to how old it is, as the decay chain won’t be in equilibrium. It will actually get more radioactive over time.
By the way. Depleted uranium is actually used as radiation shielding for e.g. medical irradiation sources, as well as for tank armor, and everyone knows about the ammunition.
For fun: read the parent as implying that wedrifid has slept on top of a cubic meter of lead for decades.
It’s so soft! There is no other metal that I’ve slept on for decades that is more comfortable than lead.
I haven’t tried a water bed filled with mercury yet. That actually has potential. The extra mass would absorb the impact or rapid movement of a human more smoothly while maintaining malleable fluidity over a slightly longer timescale. Plus if you attach a glass tube near the head of the bed you can calculate your weight based off changes in mmHg!
It’s not the mass, it’s the viscosity. The higher density would result in a ‘firmer’ feel, since less immersion would be needed for the same amount of buoyant force.
A more reasonable option might be Gallium-which would be firm on initial contact, but then liquefy.
No, really, it’s both. I edited out out viscosity since either would be sufficient and I happened to be certain about mass but merely confident about viscosity.
I assume that the primary mechanism by which mass absorbs impact would be inertia.
Malleable is a property that liquids don’t have, so what did you mean by ‘maintaining malleable fluidity’ that doesn’t also result from having the liquid in a closed container with some airspace and some elasticity? How would more inertia help absorb impact (spread the impulse out over a longer period of time)?
Accidentally rupturing a tank of mercury doesn’t usually kill a worker and injure a dozen. A tank of very nasty mercury compound might.
Actually, to steer back to topic which is (laudably tolerated here) dislike of rationalists, this argument can make good tiny pet example of ‘rationalist’ vs ‘experts’ debates.
Rationalists believe by special powers of rationality they are unusually less prone to for example nuclear = scary bias, and say that uranium wrapped in paper safe as lead etc etc. (By the way, also false, uranium is a serious fire hazard). There’s a lot of such ‘rationalists’ around, not just here but everywhere, that’s where people get misconceptions like yours from.
Experts actually know the matters to conclude something. (Not that I am a nuclear expert, of course, I only know overall overview of the process, and would defer to experts)
Frankly, rupturing any tank of just about any hexafluoride compound would be expected to be pretty dangerous.
I’m by no means a nuclear expert, I was just a nuke plant mechanic. The reason I am unafraid of radiation isn’t because the fearmongering is baseless, it’s because I’m enough of a lay expert to know the magnitude of the actual risks.
How is elemental uranium a fire hazard? Does flame spread across it faster that it spreads across wood paneling? I never considered that kind of hazard to be important, because uranium-as-she-is-used is safe enough from fire.
Actually, to steer back to topic which is (laudably tolerated here) dislike of rationalists, this argument can make good tiny pet example of ‘rationalist’ vs ‘experts’ debates.
You can tell your pet “‘rationalist’ vs ‘expert’” example has issues when it can replaced with “‘rationalist’ vs ‘anyone with a net connection and 30 spare seconds’” and it applies just as well.
Experts actually know the matters to conclude something. (Not that I am a nuclear expert, of course, I only know overall overview of the process, and would defer to experts)
You realise, of course, that this places you squarely on the ‘rationalist’ side of that artificial dichotomy?
(By the way, also false, uranium is a serious fire hazard).
Not to mention it’ll do much more damage to your toe if you drop it on yourself—so much heavier!
You realise, of course, that this places you squarely on the ‘rationalist’ side of that artificial dichotomy?
I would defer to experts, I said. This community has a well respected founder apparently leading it by example NOT to defer to experts, but instead go on how experts are wrong, on basis on something terribly shaky. (quantum sequence).
Over-hyped BS. There are regular reactors, and there are breeder reactors (fast neutron reactors), both can use uranium but only the latter type can use thorium. The latter type, also, incidentally, uses a lot less uranium than the former, and can use depleted uranium. The cost of fuel is of no consequence and all the safety issues are virtually identical for fast neutron reactors using thorium and using uranium (and for both, are expected to be significantly more severe than for regular water moderated reactors) There’s a lot of depleted uranium laying around costing negative $ . Not thorium, though.
I thought that depleted uranium wrapped in paper was pretty much as safe as lead?
Really? As in… I can sleep with a cubic metre of the stuff under my bed and not expect to get cancer within a decade or two?
Pretty much, yeah. The hexafloride is somewhat harder to contain, though. And expect long-term brain damage from the block of lead. (The decay chain of U-238 is mostly alpha and beta, which are completely absorbed by paper wrapping. There is some gamma radiation in some of the decay steps, but not significantly more than background for any reasonable amount. 18,500 metric tons of the stuff might have a total activity somewhat higher (=2.74e15 Bq), or one mole of helium produced every 70 years from direct decay alone, and a few mA’s worth of electron emissions once the decay products reach equilibrium. It looks like the half-thickness for ‘uranium’ is about 7mm for Co-60 gamma emissions.
Doing the calculus, the total unshielded activity at the surface of the block would be equal to the integral of (total activity per unit thickness {14.8 Bq/mg; DU has a density of 18.5 G/cc}*percentage unshielded at that depth)
(1000cM^2 is the cross sectional area, 1000mG/G is a conversion factor, making the first term the total activity per thickness; second term is the percentage unshielded calculated by raising 1⁄2 to the power of the number of half thicknesses of uranium above the layer in question. X is in cM.)
Overall though, the stochastic effects of ionizing radiation exposure are close enough to zero that studies of the effects of occupational exposure do not find conclusive correlations of long term low-level exposure to disease.
I don’t believe you.
It’s wrapped in paper (your stipulation) and under the bed (my stipulation). Are you asserting that the wrapped, undisturbed block of counterfactual lead under my bed is a significant airborne pollution threat?
Fascinating, thankyou.
I wasn’t wrapping the lead in paper, but that wasn’t fair of me- because frankly, inhaled DU particles ARE much worse than inhaled lead particles, because the ‘wrapped in paper’ (or painted, I suppose) is significant. DU munitions and armor aren’t ‘safe’ in the sense of failing to contaminate the nearby area, but neither are lead munitions.
I’d be more concerned about the fire hazard if you scratch it (by your depleted uranium paperweight). It’s like lighter sparkler on steroids, from what i’ve heard. The activity in practice would also depend to how depleted it is (they don’t deplete all the way to 0% u-235), and it better not be “dirty” depleted uranium from fuel re-processing. edit: also to how old it is, as the decay chain won’t be in equilibrium. It will actually get more radioactive over time.
By the way. Depleted uranium is actually used as radiation shielding for e.g. medical irradiation sources, as well as for tank armor, and everyone knows about the ammunition.
For fun: read the parent as implying that wedrifid has slept on top of a cubic meter of lead for decades.
It’s so soft! There is no other metal that I’ve slept on for decades that is more comfortable than lead.
I haven’t tried a water bed filled with mercury yet. That actually has potential. The extra mass would absorb the impact or rapid movement of a human more smoothly while maintaining malleable fluidity over a slightly longer timescale. Plus if you attach a glass tube near the head of the bed you can calculate your weight based off changes in mmHg!
I used to think that my mercury bed was a bad idea and mad as a hatter. But then I gave it a fair try for a few months, and boy did my mind change!
It’s not the mass, it’s the viscosity. The higher density would result in a ‘firmer’ feel, since less immersion would be needed for the same amount of buoyant force.
A more reasonable option might be Gallium-which would be firm on initial contact, but then liquefy.
No, really, it’s both. I edited out out viscosity since either would be sufficient and I happened to be certain about mass but merely confident about viscosity.
I assume that the primary mechanism by which mass absorbs impact would be inertia.
Malleable is a property that liquids don’t have, so what did you mean by ‘maintaining malleable fluidity’ that doesn’t also result from having the liquid in a closed container with some airspace and some elasticity? How would more inertia help absorb impact (spread the impulse out over a longer period of time)?
That’s actually a neat idea. You could use gallium/indium/tin alloy perhaps. Would be easily the most expensive fluid bed.
It’s uranium hexafluoride actually, that’s laying around.
Ah, so it’s about as safe as elemental mercury or many mercury compounds then.
Accidentally rupturing a tank of mercury doesn’t usually kill a worker and injure a dozen. A tank of very nasty mercury compound might.
Actually, to steer back to topic which is (laudably tolerated here) dislike of rationalists, this argument can make good tiny pet example of ‘rationalist’ vs ‘experts’ debates.
Rationalists believe by special powers of rationality they are unusually less prone to for example nuclear = scary bias, and say that uranium wrapped in paper safe as lead etc etc. (By the way, also false, uranium is a serious fire hazard). There’s a lot of such ‘rationalists’ around, not just here but everywhere, that’s where people get misconceptions like yours from.
Experts actually know the matters to conclude something. (Not that I am a nuclear expert, of course, I only know overall overview of the process, and would defer to experts)
Frankly, rupturing any tank of just about any hexafluoride compound would be expected to be pretty dangerous.
I’m by no means a nuclear expert, I was just a nuke plant mechanic. The reason I am unafraid of radiation isn’t because the fearmongering is baseless, it’s because I’m enough of a lay expert to know the magnitude of the actual risks.
How is elemental uranium a fire hazard? Does flame spread across it faster that it spreads across wood paneling? I never considered that kind of hazard to be important, because uranium-as-she-is-used is safe enough from fire.
You can tell your pet “‘rationalist’ vs ‘expert’” example has issues when it can replaced with “‘rationalist’ vs ‘anyone with a net connection and 30 spare seconds’” and it applies just as well.
You realise, of course, that this places you squarely on the ‘rationalist’ side of that artificial dichotomy?
Not to mention it’ll do much more damage to your toe if you drop it on yourself—so much heavier!
I would defer to experts, I said. This community has a well respected founder apparently leading it by example NOT to defer to experts, but instead go on how experts are wrong, on basis on something terribly shaky. (quantum sequence).
… and his position is held by a fair fraction of the experts.