DancingFool wrote:D Tibbets wrote:DancingFool, you are reading between the lines too much. Why would the start up of the reactor be unshielded?
DT, I'm sorry, but you've lost me. Could you please quote the statment you're referring to?
I think I misread your comment. When you said little radiation due to shielding while the machine was ruing, I read between the lines to imply you thought the machine was unshielded when it was turned on.
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I have to disagree with you there. Since gamma radiation propagates line of sight, it's just a matter of geometry. Shielding can be in segments, at differing distances from the source, as long as all 4 pi steradians are blocked.
A failure to communicate. This is what I was trying to say, straight line propagation of the radiation. But the lead shielding does not protect all possible straight line exits from the can (remember that much of the volume under the lead is thermal ' cotton like' thermal insulation. The lead is a layer outside this. I doubt the straight paths to the valves, power cords, etc are not all shiielded (they are not covered by the lead tape). There would be vectors where the gamma radiation could escape (this assumes the lead shielding is actually needed at all). Both a safety and regulatory no,- no.
Assuming there is ~ 13 kg of lead, spread over ~ 50 cm length of pipe with an radius of ~ 20 cm results in a surface area of ~ 50 cm * (20cm * 20 cm* 2 * pi) = ~ 2,000 cm^2. Estimating the lead density at ~ 14 g/ cm^3 results in a volume of lead of ~ 930 cm^3. That spread over the volume of the device covered by the lead results in ~ 0.5 cm of lead pe cm^2. That is a little less than 1/4th of an inch. That is not much lead to stope a whole lot of gamma radiation. Even at x-ray levels of ~ 30-80 KeV in a Medical X-ray room, they generally use ~ 1/8th lead in the walls and doors, etc. This by no means stops all of the stray radiation from the lead lined x-ray tube, just enough that the workers cumulative exposures do not exceed safety limits. AND this is with power outputs of merely a few hundred Watts or less (a chest x-ray may be at 50,000 V with ~ 50-1000 milliamps (I can't remember) for perhaps a 10th of a second.
The gamma ray flux from the Rossi device would be much greater, and the duration would be much greater. This makes me think that the claim that the lead shielding is actually protecting against a claimed gamma ray output is a joke!
The only out I can see is if the gammas have an energy well below 10 - 20 KeV (even that may be to0 high) or any claimed nuclear reactions that iare occurring only produces gammas in an exceedingly rare branch reaction (like 1/ 1,000,000 to 1,000,000,000th ratio). But, if proton capture is the claimed reaction, that would eliminate any neutron capture with subsequent beta decay. I'm not sure of the mechanics of proton capture, except adding a proton, or neutron to Nickel 62 is generally endothermic.*
And, if neutron capture is presented as the initiating step for the transmutation to copper, where the heck did this free neutron come from?
* I have repeatedly struggled to explain this (often very poorly), but haven't succeeded, at least with some.
If you take a collection of ~ 63 free nucleons and combine them, then of course a lot of energy will come out. But if you add one nucleon, especially a proton, to Ni62 the energy balance is negative. Ni62 is the high water mark. You cannot pack a nucleus tighter, and that is what the thermal/ kinetic energy comes from. There are possibly combinations of smaller nuclei that could still release energy with a product past Ni62, but these are rare reactions and contrary to the Rossi's claims.
Dan Tibbets
To error is human... and I'm very human.