[ RadSafe ] efficiency rating for HEPA filter in rad hood

[franz.schoenhofer at chello.at]

RADSAFErs,

There seems to be some big misunderstandings prevalent in this thread.

HEPA filter means "High Efficiency Particulate Air Filter"!  This clearly shows that they are intended for filtering particulate matter.
Further the chemical nature of "Iodine" is neglected. (I am a chemist.) For instance from a nuclear power plant there are several different iodine compounds emitted, the ratio depending on the type of of reactor. There is iodine as a negative ion, but there is also methyl iodide, ethyl iodide and molecular iodine, the latter ones gaseous and therefore by definition not collectable by a HEPA filter. In a fume hood the type of emission will depend most of all on the kind of work and which chemical form of iodine is used in. Volatility of iodine and its compounds is legendary, almost like tritium. Therefore it is not possible to give a number for "retention of iodine"!!!! You will have to specify the chemical form.  There are several methods for removing the volatile compounds from gas streams for analysis commercially available. Check suppliers. 

Best regards,

Franz



---- "Stroud schrieb:
> Hello Curtis,
> A HEPA filter, alone, would have a very low efficiency for I-131, if at all. Normally, some type of charcoal filter is used to remove/lessen these emissions. 
> 
> Ed Stroud, Compliance Lead
> Radioactive Materials Unit
> Colorado Department of Public Health and Environment
> 
> -----Original Message-----
> From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Hofer, Curtis
> Sent: Thursday, October 20, 2011 11:15 AM
> To: The International Radiation Protection (Health Physics) Mailing List
> Subject: [ RadSafe ] efficiency rating for HEPA filter in rad hood
> 
> 
> Hello,
> 
> Does anyone the efficiency rating for a HEPA filter in a fume hood that may be used for radioiodinations?  I was unable to find anything in 10 CFR 20 about fume hoods.
> 
> Thanks in advance and have a great day!
> 
> Curtis
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--
Franz Schoenhofer, PhD, MinRat
Habicherg. 31/7
A-1160 Vienna
Austria
mobile: ++43 699 1706 1227