Re: Absence of radionuclides

[LIPTONW@detroitedison.com]

The "absence of radionuclides" criteria have moved to 10 CFR 20.1204(g):
"When 
a mixture of radionuclides in air exists, licensees may disregard certain 
radionuclides in the mixture if - (1) The licensee uses the total activity
of 
the mixture in demonstrating compliance ... (2) The concentration of any 
radionuclide disregarded is less than 10% of its DAC, and (3) The sum of
these 
percentages for all of the radionuclides disregarded in the mixture does not 
exceed 30%." 
 
The opinions expressed are strictly mine. 
It's not about dose, it's about trust. 
 
Bill Lipton 
liptonw@detroitedison.com 
 
 
You wrote: 
 
The old 10CFR20 had a method in Appendix B to determine the absence of any 
radionuclides in a mixture.  If each 'absent' radionuclide was less than 10%
of 
it's MPC and the sum ratio of 'absent' radionuclides to their respective
MPCs 
were less than 25%, than those radionuclides were absent from the mixture. 
The 
new Part 20 requires that the absence of the radionuclides be demonstrated.  
These appears to be another case of "if it's detectable, it's there."  Have
any 
NRC licensees had to 'demonstrate' the absence of radionuclides in a
mixture?  
If so, how? 
 
Claude Flory 
Northeast Utilities 
floryca@gwsmtp.nu.com