Radiation change evident in linseed oil?

Andy Dingley dingbat at codesmiths.com
Sun Nov 24 20:02:39 EST 2002


On 20 Nov 2002 07:06:21 -0800, mick___ at hotmail.com (Mick) wrote:

>Any help will be appreciated.

This is the wrong place, and I'm the wrong guy to ask   (You need
Uncle Al - try sci.materials)

>The idea is that the radiation from Hiroshima
>and other sources since then has left a noticeable trace in all
>organic matter so linseed oil manufactured recently is quite easily
>distinguished from linseed oil manufactured in the 1800s, 

Seems reasonable enough.

It's not Hiroshima. The two small WW2 bombs are overshadowed by the
atmospheric tests of the '50s, and the effluent of the production
plants.

There are two effects that can be noted as a result of "fallout", one
atomic and one isotopic.

The atomic effect is the more obvious. Plutonium was non-existent
before its production in nuclear reactors, then use in weapons. Any Pu
you detect now is post 1943.  Similarly for Cesium - although it was
detectable beforehand, the prevalence of Cs-137 has been so much
increased in the atomic age that its presence is a good indication.

Isotopic changes are more subtle, and require radiochemistry
techniques to detect them, not just physical chemistry. Many elements
already exist in a mixture of two isotopes, and can be used for dating
purposes (Carbon 14 dating is the obvious example). Man-made nuclear
processes may change this (such as oxygen making entry to a BWR power
station unwise for a couple of hours after shutdown). Some elements,
such as iodine, are only found naturally in one natural isotope, but
the other is made more common by fallout. Where the natural one is
already rare (iodine deficiency is common in the Himalayas), this can
even become a health hazard.

'50s nuclear contamination is not only detectable, it's so common as
to cause problems. To count emissions from nuclear samples, it's
necessary to build a shielded "counting room". The metal used to
create this must itself be "clean", so as not to provide false counts.
Many of these rooms are made by a UK firm that "mines" pre-war steel
armour plate  from naval wrecks. The WW1 German High fleet was
scuttled at Scapa Flow, a natural harbour in Orkney, Northern
Scotland. As the steel of these ships is clean, they're in (or poking
above) shallow water, and (having being scuttled) they're not a war
grave, they're a source of suitable shielding. Bizarrely these waters
are also polluted by the nearby Dounreay reactor and reprocessing site
on the Scottish mainland.

To see how tiny quantities of a material may travel the world, then be
detected afterwards, look up Lovelock and the Electron Capture
Detector <http://resurgence.gn.apc.org/issues/lovelock187.htm>. 

I have no idea how to date linseed oil specifically (but I'd love to
know). However I can certainly believe that it's possible, and almost
a commonplace use of a well-known technique.




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