Re: I found the food numbers!

[T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden)]

Steve writes:

>KellySt@aol.com writes:
>> >> Would stored food need no protection against radiation? I'm not sure how
>> much  and if the food would become radioactive. But if it does, it may need
>> shielding too.  <<
>> 
>> No. Food would only become radioactive if radioactive particals were mixed in
>> with it.  Xrays and stuff would cause no perminent change.  Thou it would
>> keep longer.  Its actually been tested as a food preservative, and works.
>
>The real answer depends on what kind and what level of radiation the
>food is exposed to.
>
>Alpha particles (helium nuclei) and beta particles (electrons) are
>unlikely to do any damage to the food, as they will be stopped by the
>packaging.
>
>Energetic ultraviolet and X-rays may ionize atoms in the stored food and
>produce undesirable chemical changes with high exposure, but won't make
>the food radioactive.
>
>Neutrons or gamma rays could make the food radioactive by interacting
>with the nuclei of atoms in the food; neutrons can be captured by nuclei
>to produce radioactive isotopes or transmutation, and gamma rays can
>induce fission of nuclei.  Both types of radiation are likely products
>of fusion or antimatter reactions.  Neutron shielding in fusion reactors
>is actually a pretty significant problem, as the shielding itself tends
>to become radioactive.
>
>Any high quantity of radiation of the latter two classes is likely to
>cause degradation of the food over time.

Steve thanks for explaining it so clearly, it was indeed the latter that I
had in mind. A few years ago I had to do a physics-experiment with small
silver-discs. When placed near a radioactive (I think) cesium source they
became radioactive too. The specific decay of that silver was rather fast
(that was why we used it) so one had to bring it straight from the vault to
the experiment, every second counted (because we wanted to determine its
decay curve).
Of course shortlived radiotopes may not be the main problem, but I'm quite
certain that in the forest of possible isotopes one or two will give us a
hard time when the food is stored without shielding.

As far as I know there are laws for the maximum limits for food radiating
levels used to preserve food. I'm not sure though what the reason is. (It
could be that it is a precaution for people who have bad food and want to
keep it looking OK)

Timothy