[ RadSafe ] Stack Emission Limits

[Eric.Goldin at sce.com]

Otto,  If I understood your question below, you're asking about the
demonstration of compliance with the 10CFR20.1101(d) dose constraint from
air emissions.  It's been a few years since I've used it, but the COMPLY
code endorsed by EPA presents a fairly simple progressive plan to
demonstrate compliance.  The simplest level is based on possession limits,
the second level on concentration limits at the stack, the third is a
screening model based on NCRP Commentary 3 that makes conservative
assumptions about releases, and finally the fourth level is a more detailed
modeling that requires information about your facility, stack volume rates,
distances to receptors, etc.  Without knowing any more about what you're
doing, the screening model of Level 3 appears to allow for averaging of
releases over the year.  Therefore, it doesn't matter under what "profile"
the emissions occur - short bursts followed by long periods of no release.

There may be newer versions of the code and guide (what I used was Revision
2 dated October 1989) documented in EPA 520/1-89-002.  And I if I recall
the code was available on the EPA website.  I'd have to do some serious
digging but I'm pretty sure that there was guidance from the NRC that
permitted the use of the COMPLY code for demonstrating compliance with
those relatively new Clean Air Act standards.  Let me know if you have any
questions.   Eric

Eric Goldin, CHP
Southern California Edison
eric.goldin at sce.com

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February 7, 2007

10 CFR Part 20 sets annual average limitation for stack emissions in the
United States.  For example, for carbon-11 monoxide, the annual average
concentration is given as 2E-6 microcuries per milliliter of air. [Sorry
about the American units.] .

My question concerns a brief ultra-high concentration emission that may
occur only occasionally and last only a few seconds. Is there a peak limit
for such an emission? I can always run my exhaust fans for a year to get
the average down to the allowed annual average, but even if the exhaust
fans were turned off after an emission event there is no real difference in

potential exposure risk.  But it seems that I can meet the release limit by

simply running my fans while there are no emissions.

Comments please.

Otto

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