Re: xenon behavior

[baumbaug@nosc.mil (Joel T. Baumbaugh)]

     Ed,

     At  one time I worked at a university where at one time (for
months  at  a  time) a P.I. was using both X-133 and K-85  in  an
interesting  animal study (assessing/preventing stroke damage  in
primates).

     Needless  to  say,  even  with all of  our  precautions  (we
THOUGHT  we'd  thought of everything) - (more than once), we  had
leaks  develop  in the tubing/mixing bag between both the  supply
bottle  and  the patient and the breathing exhaust tubing  to  an
activated charcoal container (note: the activated charcoal worked
GREAT!).

     Under  the circumstances (upon discovering I had a leak),  I
was  unable to totally evacuate the room as we'd loose a valuable
research  subject (there was surgery involved).  Of course, I was
concerned  with  human  personnel uptake from  the  xenon  and/or
krypton.

     Needless  to  say, I performed rapid "emergency" surveys  of
the  room  with  both a collimated (lead  wrapped)  scintillation
probe  and  a G.M. pancake probe.  Note: With  the  scintillation
probe I would wrap the outside with lead foil to cut down on side
photons  and  I even tried loosely looping lead foil  around  the
front  of  it to make a (sort of) open "gas chamber" so  I  could
measure   the   xenon/krypton   gas   levels   within   a   given
area/elevation  without  being influenced by photons from  across
the room.

     Under  all cases (although there appeared to be some  mixing
with  air turbulence when I evacuated all non-critical personnel)
the  xenon/krypton did tend to displace the nitrogen and sink  to
the  floor.   Once it had sunk to the floor,  it eventually  left
the  room (under the locked door) - and slowly dispersed into the
hallway  and  down  the  stairs (we were next to  stairs  and  an
elevator on the 4th floor).  It dispersed "VERY" rapidly.

     After  the  first  "accident" I was prepared  for  the  next
"whoops"  and was ready and able to take air samples to check for
actual  gas  levels  at  different elevations  and  in  different
locations  and  can  happily say  that  the  projected/calculated
intakes to personnel were WAY below the ALI (WHEW!).

     I'm  sorry I was so "wordy" in my reply, but wanted to  give
you (or anyone else reading this) a feel for the situation - hope
this helps,


     Joel Baumbaugh (baumbaug@nosc.mil)
     Naval Research and Development
     San Diego, CA

     Std  Disclaimer  -  the opinions above are mine and  do  not
necessarily  reflect  those of my boss, the Navy or  the  Federal
Govt.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _M_e_s_s_a_g_e_ _S_e_p_a_r_a_t_o_r_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 



Date: Thu, 2 Nov 95 17:26:15 -0600
Sender: radsafe@romulus.ehs.uiuc.edu
From: LEIDHOLDT.EDWIN@FORUM.VA.GOV
To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
Subject: xenon behavior

I have a question regarding the behaviour of xenon gas in a room,
specifically  Xe-133, which is used for lung ventilation  studies
in nuclear medicine.  Some people claim that it "sinks" in a room
so that the xenon concentration is higher toward the floor; other
people   say   that  it  remains  at  approximately   a   uniform
concentration  throughout  the room.  This is an issue  regarding
the  placement  of  exhaust ducts in a room.   Does  anyone  know
whether  the  xenon concentration is markedly higher  toward  the
floor?

I will be grateful for any help with this issue.

Ed Leidholdt
US Department of Veterans Affairs
San Francisco
Leidholdt.Edwin@FORUM.VA.GOV
415-744-6243