SESSION IIIB DISCUSSION
689
ing up to 50,000 ft, are as effective in incorporating stratospheric air
as they would be, for instance, in washing away some tropospheric
contaminated inversions when penetrating them. It seems to me that
the entrainment rate at these lower levels actually is larger, Am I
correct in assuming that from the cloud tops diffusion of tropospheric
air and evaporation of moisture are directed into the stratosphere? Do
we have any indication of the properties of the convective systems?
How effectively are they entraining the contaminated air?
HALL: We don’t have
enough cases yet to really determine the
stratospheric penetration. We are not able to make any statement on
it yet.
REITER: Well, it seems to me that maybe we could talk the AEC
into making some measurements of this kind since it would be quite
interesting from various points of view.
TORREY: Mr.
Pelletier,
during your work around the Fermi
reactor, you found that all the gross beta activity couldn’t be recovered
from the rain because of activity sticking in the polyethylene containers. Were you able to solve this problem ?
“PELLETIER: I think so, We use tracer mz‘erial in the rain jug
before we put it out for exposure and use several acid rinses to clean
the jug after it has been exposed. We have scraped out the inside of one
of these jugs after an exposure but found insignificant radioactivity in
the scrapings.
ZIEMER: In reporting gross beta activity, what is your standard
of reference, and do other laboratories use the same reference standard ?
PELLETIER: We use 2“T1, I don’t know what standards other
laboratories use,
ZIEMER: Do you think this would account for some of the differences in the values you reported?
PELLETIER: Well,
remember
we
are plotting a ratio. Since
both air and rain are presumably calibrated on the samebasis, the
counting efficiency, regardless of the standard used, will cancel out.
I don’t think the use of different standards could account for the differences in values. Mr. Huff, have you measured total deposition over
a time and then compared it with that from the convective storms
only ?
HUFF: No. Our work has been entirely concerned with convective
type rainfall, We have done very little with the stable, winter type
precipitation.