[ RadSafe ] Re: radsafe Digest, Vol 48, Issue 3

Mark Sonter sontermj at tpg.com.au
Thu Jun 22 19:14:23 CDT 2006

Thanks to all those who responded re thorium in lamp mantles.

Several comments on them being great demonstration and check sources; 
there are still radioactive ones to be found (I find the made-in-India 
ones are radioactive, others maybe not, have to check); round figure for 
Th232 activity appears to be 1 kBq or so; and committed dose by 
ingestion appears to be a couple of mSv for adult, up to maybe 20 or 30 
for infant.

Mark Sonter

ps  I have found to my embarrassment that you do NOT store your mantle 
check source in the same box as alpha filter counter drawer assemblies, 
as they contaminate easily with the thoron daughters.......requiring a 
couple of days to decay away to give sensible (zero) background.


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