Kr-85 and Xenon

[goldinem@SONGS.SCE.COM]

Regarding the discussion on Kr-85 and Xenon in airborne effluents:

UNSCEAR's 2000 report on Sources shows that the nuclear fuel cycle

contributes xenon(s) and Kr-85 to the atmosphere among other radionuclides,

but by my reckoning, I would call these sources trivial.  First of all,

recognize that nuclear power plants discharge very little Kr-85 and the

UNSCEAR report shows most Kr-85 (~10 year half life) is from fuel

reprocessing.  Xenons are released in larger quantities from power plants

but xenons have much shorter half lives, so don't contribute much if any

dose to anyone outside of the immediate plant locale.  UNSCEAR's Annex C

Tables show that Kr-85 isn't significant enough to report for power plants

and for reprocessors, the collective dose estimates from Kr-85 releases are

dwarfed by C-14 doses (and no one cares about C-14 since it's also

"natural", right?) mostly due, I assume to half-lives.



Additionally, UNSCEAR noted that the dose assessment is based on a model

that is not site-specific but assumes certain population densities

generically around the various plants (worldwide).  The collective dose

from electrical generation worldwide was estimated in the 500 person-Sv

range.  Pretty small compared to something like 18 million person-Sv for

the global population (my estimate based on 6 billion people times 3

mSv/yr).  UNSCEAR showed the typical light-water reactor (what the US has)

contributing something like 5 -10 microSv (0.5 - 1 mrem) per year to the

local population.  That's pretty small and I can assure you, a very

conservatively calculated (and hypothetical) figure.



Bottom line: truly trivial radiation exposures from nuclear power when

viewed in light of mother nature.

Eric M. Goldin, CHP

<goldinem@songs.sce.com>



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