ENVIRONMENTAL CONTAMINATION
General
Since September 15, 1961, most of the nuclear test detonations at the Nevada Test Site have been conducted in underground
chambers.
This technique was used in an attempt to prohibit the
release of radioactive material off the test site.
As indicated
in Table III, of the 52 underground nuclear detonations held in
Nevada, eight have released some gaseous radioactivity measurable
off-site.
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The physical characteristics and relative amounts of various
isotopes released by these tests vary somewhat from those released
by past tests at NTS.
Although there have been four surface or
near surface detonations, plus one cratering shot giving off-site
fallout resembling that from pest test series, the major portion
of the activity in the remainder of the series has been contained
on-site or underground.
Minimal amounts of gaseous activity, along
with small quantities of particulate material containing activity,
have been released to the atmosphere through venting of underground
detonations.
DOE ARCHIVES
In test series prior to 1961, nuclear devices were airdropped
or were detonated -on steel towers, balloons or in uncovered shallow
holes; thus, fallout particles contained many kinds of debris in
addition to the radioactivity.
Induced activity in the debris
as
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