Atmospheric Release from Underground tests?

["Kenneth W. Price" <75301.361@compuserve.com>]

As an  "X" nuclear weapons tester from Nevada, underground tests are
conducted to avoid releases to the atomosphere.  Holes are drilled into the
ground, the depth of which depends on the yield of the device.  The device
is placed into the hole with its cables attached and the hole back filled
and plugged with various types of materials to prevent leakage. 
Ordinarilly there would be a low risk of a leak for the experienced  test
group.  The pressure from the detonation can cause fissures and leaks of
fission gases could therefore occurr.  Depending on the time after
detonation the radionuclide gas inventory would vary, but most fission
gases are present.   It is even possible for gas to leak up the cable
insulation, etc., and cables would usually be intentionally spliced with
the splices encapsulated in some sort of gas blocking material.  Perhaps
these days cables are obsolete.  The most significant leak would occur if a
fracture or fissure occurred shortly after the detonation or after the
collapse crater is produced.  

Kenneth W. Price, MPH,CHP
University of Connecticut Health Center
Farmington, Ct.
75301.361@compuserve.com