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OTHER MAJOR ACTIVITIES
about a hundred years to ald in excavation. First, to break up earth
and rock so that it could be moved. More recently, they have been
used in larger quantities, not only to break up the earth and rock, but
tomove it. This latter technique is generally knownas diffusion blasting and has apparently been most highly developed in the Soviet
Union.
It has been recognized since the inception of the Plowshare Program in 1957 that the application of nuclear explosives to most excava-
tion projects depends largely upon the successful development of
nuclear explosives with less radioactivity and refinement of cratering
technology to permit more accurate cratering predictions.
Cratering explosions can be used to excavate canals, for both transportation and water conveyance, to make highway andrailroadcuts,
and to make harbors. Other uses include removing overburden in
mining operations and constructing water reservoirs.
Effect of Limited Nuclear Weapon Test Ban Treaty
The nuclear Test Ban Treaty prohibits weapontests or any other
nuclear explosion in the atmosphere, outer space, or underwater (both
territorial and open seas). It permits underground nuclear explosions
provided they do not cause radioactive debris to be present outside
the territorial limits of the nation under whose jurisdiction or control
the explosion takes place. All cratering explosionsresult, bydesign,
in sufficient disturbance of the surface of the earth to permit some
radioactivity to reach the atmosphere. The amountof radioactivity
depends primarily upon the yield of the explosive, the depth at which
the explosive is emplaced, and the amountof fission which takes place
in the explosion. Other factors are the chemical and physical properties of the medium. Upon detonation, the radioactivity produced in
the underground detonation region is selectively trapped according
to its form in the process of crater formation. That whichis released
to the atmospherefalls out, mostly near the detonation site, according
to the size of the particles to which it adheres, or disperses in the
atmosphere.
With proper design, taking the above factors into account, and
sufficient distanceto territorial boundaries, it appears that some meaningful cratering experiments can be carried out to help develop excavation technology without causing radioactive debris to be present
beyond national boundaries.
MajorActivities
There were no nuclear excavation experiments in 1963, and the main
progress was madein theoretical understanding through laboratory