Wow, neutron activation is rather nasty stuff. How it works is that the neutrons are absorbed by the nucleuses of the atoms, which then end up being another isotope of the same element, but with an atomic weight of one more. Many, if not most elements then become radioactive, and will decay after some period of time. Some, such as uranium 235 will fission. When the atom decays, it may emit an alpha, beta, or gamma ray. If the atom fissions it may emit one or more neutrons. The alpha and beta rays will not get out of the container, but the gammas, which are very hard X-rays will. These gamma rays will have an energy signature which allows them to be identified as being from a certain element. So the atomic composition of what was exposed can be determined.
Now the problem is that many will decay immediately, but others take longer. Some can take as long as several thousand years to decay. The sort decay, and extremely long decays are not a problem, since the first will be gone very quickly, and the second will most likely not decay during your lifetime, but the intermediate lifetime isotopes, a few day to a few years could add significantly to ones exposure to radioactivity. The result would be an increase in the death rate due to cancer across the board. Marshall Nancy Venzon wrote: > My friend George actually reads the Federal Register every day, his > job as chemist makes it necessary, I am glad that he does, its dry > reading but we need to be vigilant of what is becoming law out > there...Thanks to George...: Guess what? You just got a last-minute > Xmas present from the > FDA. And in this case, I really MEAN Xmas as in X RAY. Because > believe > it or not, they just quietly approved AS A FOOD ADDITIVE the use of > high-energy neutron bombardment of containers 'that might contain > food' as a surveilance method to detect contraband in trucks and sea > containers and, one presumes, > conceivably our suitcases and so forth. This is the big kahuna of > food irradiating: unlike irradiating food directly with Xrays or > gamma rays, which arguably does some damage to food molecules but > doesn't actually leave them radioactive, neutron bombardment is such > a powerful method of irradiating that it not only induces gamma > radiation IN the food but it > actually DOES leave it radioactive. Well, OK, just a little. The > exposure will be pretty brief, they promise, typically just a few > seconds! , which if you twist my arm I will readily admit will > produce an infinitesimal amount of radiation only, with a fairly > short half-life, that in actual > fact will (probably) do little damage. Though they admit that in > 'iffy' cases they might have to blast something with their energy > particle beam (beloved by 'Buck Rogers' fans everywhere) for 'as much > as 5 minutes'. (Or perhaps a little more, if the inspector forgets > to turn his unit OFF before leaving for his coffee break.....) They > present a bunch of data to show that this practice is harmless, and > actually the numbers don't look all that alarming to me, mostly > because this isn't something that food will be getting routine > exposure to--this is a method of spot-checking only, one would > hope!--so this individual contribution to that proverbial bushel of > dirt you have to eat before you die doesn't seem all that significant > to me. ! But it's just > one more thing you are being exposed to that nature probably didn't > actually PLAN for you to eat...and in any case I wanted to let you > know what your tax dollars have been up to lately. Here's the > reference, from the Federal Register: > http://a257.g.akamaitech.net/7/257/242 > /06jun20041800/edocket.access.gpo.gov/2004/04-27868.htm
