[ RadSafe ] Re: krypton-85
franz.schoenhofer at gmail.com
Fri Aug 18 05:55:47 CDT 2006
Activated charcoal (and molecular sieves) has since long been used in the
determination of Kr-85, though in traps cooled by liquid nitrogen. The
charcoal diffusion delay lines are to my knowledge used to delay the
diffusion of I-131 and other shortlived gaseous radionuclides so that they
decay before reaching the open atmosphere. For Kr-85 with its 10 years
halflife this would not work.......
Kr-85 is a "problem" only at reprocessing plants, where it usually is
emitted in high amounts into the air. About 20 years ago at the research
center in Karlsruhe, Germany, several methods had been developed for the
separation of Kr-85 from the offgases, but the reprocessing plant in
Wackersdorf was cancelled and to my knowledge Kr-85 is at existing
reprocessing plants not isolated. Anyway the dose from Kr-85 (beta-emitter,
maximum beta-energy 687 keV) to the population is negligible.
BTW: A search on google for "Kr-85 activated charcoal" yields within
0.09sec 271 entries!
2006/8/17, John Jacobus <crispy_bird at yahoo.com>:
> This may be of interest.
> "The Adsorption of Argon, Krypton and Xenon on
> Activated Charcoal."
> Health Physics. 71(2):160-166, August 1996.
> Underhill, Dwight W.
> Abstract: Charcoal adsorption beds are commonly used
> to remove radioactive noble gases from contaminated
> gas streams. The design of such beds requires the
> adsorption coefficient for the noble gas. Here an
> extension of the Dubinin-Radushkevich theory of
> adsorption is developed to correlate the effects of
> temperature, pressure, concentration, and carrier gas
> on the adsorption coefficients of krypton, xenon, and
> argon on activated carbon. This model is validated
> with previously published adsorption measurements. It
> accurately predicts the equilibrium adsorption
> coefficient at any temperature and pressure if the
> potential energies of adsorption, the micropore
> volume, and the van der Waals constants of the gases
> are known.
> --- Cehn at aol.com wrote:
> > Years ago, I was involved in noble gas clean-up at
> > nuclear power plants.
> > Activated carbon is used to hold up noble gases for
> > decay. That is, the carbon
> > traps the gas then releases it, then traps it again.
> > The longer the filter
> > train, the longer the holdup. So you can get a
> > temporary hold on Kr-85 with
> > carbon.
> > Joel I. Cehn, CHP
> > 1036 Hubert Road
> > Oakland, CA 94610
> > 510.268.1571
> > ------------------------------
> > Message: 6
> > Date: Wed, 16 Aug 2006 06:20:38 -0500
> > From: "Krzesniak, Michael F"
> > <krzesniak at atd.crane.navy.mil>
> > Subject: [ RadSafe ] krypton-85
> > To: radsafe at radlab.nl
> > Message-ID:
> > <C065F28430EFC94B8324914785D756A44DB6D3 at OSPREY>
> > Content-Type: text/plain; charset="windows-1252"
> > RadSafe,
> > Is it possible to capture krypton-85 gas using
> > activated carbon or other
> > filtration methods?
> > thank you
> > Michael Krzesniak
> > Crane Division, Naval Surface Warfare Center (NSWC
> > Crane)
> > Harnessing the Power of Technology for the
> > Warfighter
> > Code 6054 Bldg. 3059
> > 300 Highway 361
> > Crane, IN 47522-5001
> > Email: krzesniak at atd.crane.navy.mil
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> >From an article about physicians doing clinical studies:
> "It was just before an early morning meeting, and I was really trying to
> get to the bagels, but I couldn't help overhearing a conversation between
> one of my statistical colleagues and a surgeon.
> Statistician: "Oh, so you have already calculated the P value?"
> Surgeon: "Yes, I used multinomial logistic regression."
> Statistician: "Really? How did you come up with that?"
> Surgeon: "Well, I tried each analysis on the SPSS drop-down menus, and
> that was the one that gave the smallest P value"."
> -- John
> John Jacobus, MS
> Certified Health Physicist
> e-mail: crispy_bird at yahoo.com
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