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JANUARY-DECEMBER 1963
221
minimum number of caretaker personnel, to await the outcome of the
device development work.
The use of a nuclear explosive for producing transplutonium elements involves exposing a target, such as, uranium 238, to the intense
neutron flux produced by nuclearreactions. The nearly-instantaneous multiple neutron capture results in isotopes with higher atomic
numbers and greater masses than the target element. Using nuclear
explosives, the target undergoes neutron exposures equivalent to years
of irradiation in the highest flux nuclear reactor and also avoids the
barriers formed,in reactor irradiation, from the production of isotopes
with short half-lives.
For Coach a special nuclear explosive is required to produce an
intense neutron flux with relatively low total yield. Development
of such a device has been underwaysince late 1962 with tests being
continued at the Nevada TestSite.
Experimental Results
The potential of the nuclear explosive approach to producing
transplutonium isotopes was shown by the Mike event, a high-yield
thermonuclear explosive fired at Eniwetok in November 1952. The
debris from the explosion was foundto be rich in transuraniumelements, including two newelements, einsteinium and fermium (atomic
numbers 99 and 100), plus newisotopes of plutonium, americium.
curium, and californium. Other high-yield thermonucleartests have
produced heavy elements, but in lesser amounts than the Mike event.
On November 27, 1962, in the Anacostia event, a thermonuclear
device being developed for Project Coach was fired undergroundat
the Nevada Test Site. One of the objectives achieved was to ensure
that the target would be subjected to a uniform neutron flux, thus
making data analyses less ambiguous.
Radiochemical analysis of
the debris showed that elements at least through mass number 246
were formed in quantities comparable to those from Mike.
Other Development Work
Two other aspects of Project Coach are being pursued. First,
prompt sampling techniques were developed to provide samples of
debris from the detonation region immediately after the detonation.
The technique collects samples brought to the surface through a pipe
leading from the detonation region. By this method it should be
possible to obtain small quantities of isotopes with very short halflives. Prompt sampling combined with samples obtained by core
drilling into the cavity region within a few days after the detonation