Newsgroups: sci.energy
From: John De Armond
Subject: Re: Nuclear vs. Renewables... again
Message-ID: <=mz2!y_@dixie.com>
Date: Thu, 16 Dec 93 19:29:04 GMT

>>olsson@plasma.kth.se (Goran Olsson, Plasma Physics, KTH) writes:

>Right now a sizable fraction of the radiation you receive comes from
>Xe & Kr liberated from the military Pu reprocessing over the last five
>decades.

This is the kind of rank ignorance we have to deal with, isn't it.
This is an absolutely fantastic claim considering that the longest
lived isotope of Xe is Xe-133 at 5.24 days and decays with a weak
beta and a weaker gamma; and that of Kr is Kr-85 at 10.73 years,
decaying with a weak beta and a very weak gamma. (I'm ignoring
Kr-81 with a half life of 2E5 years.  It's fission abundance is
very low and besides the very low specific activity means it doesn't
do much.)

What this says is all the Xe is gone in a couple of weeks after release
and the Kr is gone in a few decades.  Besides both gases are heavy enough
that they settle out of still air in short order, as I well know from
personal experience, having accidentally released a couple hundred
curies of Kr-85 and then tracked it for a few days.

John

Newsgroups: sci.energy
From: John De Armond
Subject: Re: Nuclear vs. Renewables... again
Message-ID: <p822acr@dixie.com>
Date: Sun, 19 Dec 93 07:52:43 GMT

pereckas@uxa.cso.uiuc.edu (Michael Pereckas) writes:

>jgd@dixie.com (John De Armond) writes:

>>and the Kr is gone in a few decades.  Besides both gases are heavy enough
>>that they settle out of still air in short order, as I well know from
>>personal experience, having accidentally released a couple hundred
>>curies of Kr-85 and then tracked it for a few days.

>Someone has to ask:  What did you do, John?  There has got to be at
>least a moderatly interesting story behind this.

My company in the 80s specialized in designing, building and calibrating
RegGuide 1.97 post accident monitors.  We did a full scale calibration with
Kr and Xe on each.  We learned quickly that the Kr could be poured like
water out of its shipping container, down some large bore tygon tubing
and into the monitor.  We also found that we had to maintain a high flowrate
through the monitors lest the Kr settle in the bottom of the sample
chamber.  When we were finished with the Kr, we froze it out on a cold
finger full of activated charcoal cooled with liquid nitrogen.  One
afternoon, one my my technicians captured a couple hundred Ci in the
cold finger, clamped off the ports and then forgot about it.  When the
Dewar boiled dry, the cold finger exploded.  The gas ran along the
floor, down about 3 flights of stairs to the basement of the old
experimental reactor building we were working in and settled on the floor.
A survey meter would be almost quiet until you got the probe within
a couple of inches of the floor.  You could stir it up with your feet
and it would settle back in.  The building ventillation system had
no effect on it.  We finally got a fire department smoke ejection fan
to get the stuff out.

John

Newsgroups: sci.energy
From: John De Armond
Subject: Re: Disposal of Gaseous Nuclear Waste
Message-ID: <t-4gnqn@dixie.com>
Date: Mon, 03 Feb 92 14:50:52 GMT

strickla@gn.ecn.purdue.edu (George T Strickland) writes:

>In article <53869@cup.portal.com> mmm@cup.portal.com (Mark Robert
>Thorson) writes:

>>I've heard that radioactive krypton and xenon gas are normally
>>released to the atmosphere during nuclear power plant operations.
>>These are fission products which happen to be gases.  I'd like
>>to know if there are any recovery systems for these gases, or
>>is the whole amount generated by fission released?

>If you are in reference to the Krypton and Xenon relased in the fuel
>as fission products, they are retained in the fuel.  A small amount may
>leach through the cladding but it would be a SMALL amount.  I know of
>no operating plant that releases any Krypton or Xenon.  The fission
>yield of Kr is about 1.3% from 3% enriched U-235.  I don't have the
>numbers on Xe with me right now but if there is interest I'll post
>them.

Not quite true.  There are always failed fuel pins in any operating
core.  Tech specs place limits on the percentage.  As a practical result,
there is always some noble gas released from the core.  As a result,
all plants are equipped with what is called the off-gas processing system.

The two isotopes of concern are Xe-133 and Kr-85 with half-lives of
5.25 days and 10.6 years respectivly.  The OGPS simply concentrates the
off-gas and holds it in tanks until the Xe-133 decays.  Then the remaining
Kr-85 is slowly purged to atmosphere at a rate in keeping with the
plant's tech spec limit on emissions.

The total annual quanitity released for a 1000 MWE plant is in the few
tens of curies, physically a few grams.

John