Re: Tritium Dose Conversion Factor Confusion

["Scott O. Schwahn" <schwahn@CEBAF.GOV>]

At 03:55 PM 1/16/96 -0600, Mr. Presley wrote:
>     I am pondering the numbers used for Dose Conversion Factors for
>     airborne exposure to Tritiated Water.
>     
>     ICRP-30 Part 1 pg 65 states that it includes allowance for
>     the absorption through skin.
>     Using the numbers quoted there I "backcalculate" a DCF
>     of about 6.2 E-5  rem/uCi
>     
>     However, in ICRP 68 pg 75
>     The corresponding number for tritiated water is
>     1.8E-11 Sv/Bq  or about 6.6 E-5 rem/uCi.
>     But this table states that skin absorption is NOT accounted for.
>     
>     Can anyone clear this up for me ?
>     I would expect the ICRP 68 value to be about 40%
>     smaller if skin absorption has not been included.


The recommendations of DOE/EH-0071 (Internal Dose Rate Conversion Factors
for Calculation of Dose to the Public), taken from ICRP Publications 26,30,
and 48 indicates a conversion factor 6.3E-05 rem/uCi uptake, either from
ingestion or inhalation.  

DOE/EH-0070, External Dose-Rate Conversion Factors for Calculation of Dose
to the Public, have factors based on Oak Ridge National Laboratory
methodology, but use weighting factors based on ICRP recommendations.  This
report indicates a 0.0 conversion for -external- exposure (immersion in)
contaminated air, contaminated water, or exposure from a ground surface.

Hope this helps, although it doesn't answer your question directly.

Scott O. Schwahn, CHP
Operational Health Physicist
Continuous Electron Beam Accelerator Facility
(804)249-7551 (w)
(804)249-7363 (fax)