Production of useful isotopes and their recovery
Connecting underground aquifers
Stimulating flow of natural gas in “tight” underground formations
In the end, the most promising use proved to be stimulation of natural gas production, which was also an active part of the Russian PNE program. Public opposition to the tests, concerns about contamination, the potential for radioactive gas flaring operations and other environmental hazards, tritium-contaminated gas, and poor economics related to gas production conspired to bring an end to the U.S. PNE program in 1975 (DOE/NV–209-REV 15).
The former Soviet Union’s PNE testing program had stronger support, and paralleled the themes of intended uses as seen in the United States, specifically,
Experiments to develop craters and move earth (such as the PechoraKama rivers canal and the village of Udachny in Yakutia-Sakha, and the Chagan River valley in Semipalatinsk Oblast)
Creation of cavities in salt mines for petroleum and possibly liquid radioactive waste storage
Enhancement of gas release and control of crude oil flow (such as Ust-Balyk in Tyumen Oblast, Grachevsky deposit in Bashkortostan)
Underground blasts for seismic probing of the earth’s crust and mantle
Restoration after accidents and fires in gushing oil wells
A map of the locations of the former Soviet Union’s PNE program is shown in Figure 18-1.
As a brief summary, the products of a nuclear explosion are distributed in the following places, constituting the initial source term for potential migration of contaminants (National Research Council, 2000):
The solidified puddle of melted rock in the bottom of the cavity
On surfaces within the cavity and, in some cases, the borehole
On surfaces in natural and explosion-induced fractures
In the atmosphere
While the emphasis seems to be placed on radionuclides, it should be noted that the presence of a chemical source term (such as lead or arsenic) derived from the weapons package, rigging, cables, and instrumentation needs to be addressed as well.
The leaching of radionuclides from the rubble left from the nuclear explosion is an important pathway for tests that were conducted under the water table or in or under perched aquifers. With time, groundwater gradually flows back into the cavity and chimney and comes into direct contact with the radionuclides.