ICRP-30 and 10 CFR 20

[eh_carbaugh@ccmail.pnl.gov]

     The regulations (10 CFR 20 for NRC and 10 CFR 835 for DOE) do not 
     specify biokinetic models or dose conversion factors for internal dose 
     assessment.  Obviously some such models had to be used to derive the 
     DAC and ALI values contained in the appendices to the regulations, 
     thus use of those DAC and ALI values for any regulation-derived dose 
     conversion factor implies a default acceptance by the licensee of 
     whatever model was used to derive the DACs and ALIs.
     
     Regulatory Guide 8.34 does identify ICRP-30 dose conversion factors as 
     acceptable for factors for compliance calculations.  This is a de 
     facto endorsement of the ICRP-30 models.  However, remember that 
     regulatory guides are not mandatory.  The same guide also permits use 
     of individual or material-specific information.
     
     There is nothing that prevents use of other models for the biokinetics 
     associated with internal dosimetry.  It's ok to use the new ICRP-67 
     models, the ICRP-66 lung model, and whatever excretion or retention 
     model you believe you can justify.
     
     What prevents blanket adoption of the newer ICRP approach is that the 
     regulation very clearly specifies what organ/tissue weighting factors 
     are to be used - and these are clearly the ICRP-26/30 weighting 
     factors.  Without a change to the regulations, one may not use the new 
     ICRP-60 weighting factors for compliance dosimetry.  Of course, 
     nothing prevents you from calculating using both systems.
     
     Our European Union friends recently approved a directive to adopt the 
     ICRP-60 recommendations and have them incorporated into national 
     legislation by the year 2000.  Given how long it took for the United 
     States to revise 10 CFR 20 to address ICRP-26 concepts, I suspect 2005 
     or 2010 is a more likely date for the US!  But then, I'm an optimist.
     
     Gene Carbaugh
     Internal Dosimetry
     Pacific Northwest National Laboratory
     eh_carbaugh@pnl.gov