But those atoms, with the exception of nitrogen, also have low neutron capture cross sections...
Yup, exactly.
and the neutron doses you’d get from 2KW source running for many hours would be huge.
Admittedly I haven’t run the numbers on whether this dose might be so huge it could activate a dead body by neutron capture, but I’d guess it’s unlikely. It’s really, really hard to make an organism radioactive just by zapping it with neutrons. (Sayeth the ’pedia: “Steam and water may be radioactive only because of dissolved or mechanically mixed contaminants, not because of activation of the water itself. [...] Finally, the largest part of life chemistry is also immune from neutron activation”.)
It’d be much more like Tokaimura criticality accident than cold fusion. I know that the soldiers who died in SL-1 accident had to be buried specially, not entirely sure though if that was neutron activation.
I doubt it was neutron activation. The SL-1 reactor had been running for 2 yearswhen it blew up and most of the water & steam in the reactor vessel escaped. The water would’ve contained some of the fission products, which would be enough to explain the contamination without invoking neutron activation. (Interestingly, the Wikipedia entry does refer to neutron activation, but only of gold from a wristwatch buckle and copper from a cigarette lighter screw.)
Finally, the largest part of life chemistry is also immune from neutron activation”.)
But with low neutron capture cross sections, the neutrons are left available to activate elements that are present at low concentrations and have high capture cross sections. At 2 kW and 10 MeV per neutron you’d have ~ 10^15 neutrons per second...
(Interestingly, the Wikipedia entry does refer to neutron activation, but only of gold from a wristwatch buckle and copper from a cigarette lighter screw.)
Well, I’d think those were useful for measuring the doses...
so, 0.05 Sv of neutrons, which I presume is on order of 0.05*80/10 = 0.4 joules (where 80kg is the weight of our unlucky cold fusion researcher and 10 is the dose equivalent factor for neutrons, albeit I am not entirely sure how dose equivalent works for low energy neutrons) , converts to 7KBq of Na-24 . Though, Na-24 has half life of 15 hours so this one is not a very big problem. But its clear that with a few watts absorbed for hours, the corpses, while perhaps not being a big health hazard, would be rather radioactive for some short while due to Na-24 alone…
edit: reading the pdf now, it says that 0.5..3 * 10^-6 Gy of gamma and neutrons from a criticality roughly corresponds to 1Bq of Na-24 in the whole body. With kilowatts of power, one could conceivably be getting 1Gy/s somewhere in the vicinity of such things, and running for tens hours at 1 Gy/s, one could conceivably end up with around 1 Ci of Na-24 in the corpse. edit: misread Gy as Sv at some point.
You motivated me to put numbers from this breakdown of elements in the body into a neutron activation calculator. Using the setting for thermal neutrons, it suggests you’d get even more activated Rb, Br, Cu, Al & I than Na-24 (~350 Ci total a 10-hour exposure to a point source 2 metres away that emits 10^15 neutrons per second). I don’t know how different things would be for the fast neutrons a fusion reactor would spit out; the calculator doesn’t say. I’d guess it’s not as bad but I’m not a health physicist.
Still, you’ve got a fair point, although most of the danger would come before the body’s six feet under (most of the relevant half-lives are short).
Well, the neutrons would get moderated by the water in the body rather well… i’m thinking the elements being essentially dissolved in moderator should make it worse overall.
I wonder how much activity would remain in the corpse after a week. To qualify as “short lived waste”, the body would need to have less than 400 KBq/Kg of >30 years half life isotopes: http://www.iaea.org/ns/tutorials/regcontrol/intro/glossaryw_z.htm#W29 . I don’t know what are the regulation for corpses though.
edit: speaking of which, other thing that’s very fishy about “cold fusion”, especially expanded to include transmutation of nickel, is that it never produces radioactive isotopes. On one hand you have those ridiculously high power outputs, on other hand not even a very small fraction of energy comes in form of gamma rays or high energy particles.
If I believed in cold fusion, I’d be experimenting in middle of nowhere, in a basement of a shed, remote viewing only, wearing a dosimeter, with a radiation alarm and so on edit: In fact one of my friends likes to mess with high voltage, and he got a dosimeter and everything for x-rays that are easy to inadvertently produce). It seems to me that one good way to identify pseudoscience is to ignore the talking beliefs, and look at walking beliefs (I mean, action inducing beliefs). The talking beliefs are, well, cold fusion works, but the walking beliefs are, no it does not, and therefore I don’t need a dosimeter (unless it is part of the talk).
Yup, exactly.
Admittedly I haven’t run the numbers on whether this dose might be so huge it could activate a dead body by neutron capture, but I’d guess it’s unlikely. It’s really, really hard to make an organism radioactive just by zapping it with neutrons. (Sayeth the ’pedia: “Steam and water may be radioactive only because of dissolved or mechanically mixed contaminants, not because of activation of the water itself. [...] Finally, the largest part of life chemistry is also immune from neutron activation”.)
I doubt it was neutron activation. The SL-1 reactor had been running for 2 years when it blew up and most of the water & steam in the reactor vessel escaped. The water would’ve contained some of the fission products, which would be enough to explain the contamination without invoking neutron activation. (Interestingly, the Wikipedia entry does refer to neutron activation, but only of gold from a wristwatch buckle and copper from a cigarette lighter screw.)
But with low neutron capture cross sections, the neutrons are left available to activate elements that are present at low concentrations and have high capture cross sections. At 2 kW and 10 MeV per neutron you’d have ~ 10^15 neutrons per second...
Well, I’d think those were useful for measuring the doses...
Interesting study on sodium activation:
http://www.ncbi.nlm.nih.gov/pubmed/11791757
so, 0.05 Sv of neutrons, which I presume is on order of 0.05*80/10 = 0.4 joules (where 80kg is the weight of our unlucky cold fusion researcher and 10 is the dose equivalent factor for neutrons, albeit I am not entirely sure how dose equivalent works for low energy neutrons) , converts to 7KBq of Na-24 . Though, Na-24 has half life of 15 hours so this one is not a very big problem. But its clear that with a few watts absorbed for hours, the corpses, while perhaps not being a big health hazard, would be rather radioactive for some short while due to Na-24 alone…
edit: reading the pdf now, it says that 0.5..3 * 10^-6 Gy of gamma and neutrons from a criticality roughly corresponds to 1Bq of Na-24 in the whole body. With kilowatts of power, one could conceivably be getting 1Gy/s somewhere in the vicinity of such things, and running for tens hours at 1 Gy/s, one could conceivably end up with around 1 Ci of Na-24 in the corpse. edit: misread Gy as Sv at some point.
Upvoted for doing a Fermi calculation.
You motivated me to put numbers from this breakdown of elements in the body into a neutron activation calculator. Using the setting for thermal neutrons, it suggests you’d get even more activated Rb, Br, Cu, Al & I than Na-24 (~350 Ci total a 10-hour exposure to a point source 2 metres away that emits 10^15 neutrons per second). I don’t know how different things would be for the fast neutrons a fusion reactor would spit out; the calculator doesn’t say. I’d guess it’s not as bad but I’m not a health physicist.
Still, you’ve got a fair point, although most of the danger would come before the body’s six feet under (most of the relevant half-lives are short).
Well, the neutrons would get moderated by the water in the body rather well… i’m thinking the elements being essentially dissolved in moderator should make it worse overall.
I wonder how much activity would remain in the corpse after a week. To qualify as “short lived waste”, the body would need to have less than 400 KBq/Kg of >30 years half life isotopes: http://www.iaea.org/ns/tutorials/regcontrol/intro/glossaryw_z.htm#W29 . I don’t know what are the regulation for corpses though.
edit: speaking of which, other thing that’s very fishy about “cold fusion”, especially expanded to include transmutation of nickel, is that it never produces radioactive isotopes. On one hand you have those ridiculously high power outputs, on other hand not even a very small fraction of energy comes in form of gamma rays or high energy particles.
If I believed in cold fusion, I’d be experimenting in middle of nowhere, in a basement of a shed, remote viewing only, wearing a dosimeter, with a radiation alarm and so on edit: In fact one of my friends likes to mess with high voltage, and he got a dosimeter and everything for x-rays that are easy to inadvertently produce). It seems to me that one good way to identify pseudoscience is to ignore the talking beliefs, and look at walking beliefs (I mean, action inducing beliefs). The talking beliefs are, well, cold fusion works, but the walking beliefs are, no it does not, and therefore I don’t need a dosimeter (unless it is part of the talk).