Origin of a decontamination mix

["Normand Freničre" <nfreniere@hotmail.com>]

In Canada, our atomic energy regulatory agency (AECB) publishes several 
information posters on different subject. Their poster numbered 
INFO-0546-1 treating of RADIOISOTOPE SAFETY of Iodine-131 gives 
different precautions. 
Precaution number 9 is read as:
" Clean up spills of radioisotopes with a solution of 0.1M sodium 
iodine, 0.1M sodium hydroxide and 0.1M sodium thiosulphate "

Could someone know why that mixture is appropriate for iodine 131? Why 
those proportions and why those three compounds? With NaI, what are the 
reactions?

I have tried to get an answer from an AECB's evaluation agent, but he 
could not found where it comes from and could not explains the chemical 
reactions that would make that mixture suitable for decontaminating 
iodine 131 spills.

Normand Freniere
Service of radiophysics
Maisonneuve-Rosemont Hospital
Montreal  (Quebec) H1T 2M4
E-mail: nfreniere@hotmail.com



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