X. COSTS AND CONCLUSIONS

The ultimate test of a new technique for construction or development is, of course, its economic and engineering feasibility. Not only must a proposed project be technically sound, but the total costs involved must be competitive with those of other methods of achieving the same or similar objectives. In the case of a new, untested technique, there must be considerable savings accruing (in the form of time, money, permanence, or accomplishment) from the use of a novel approach before an industrial concern or a governmental agency will forego the comfort of more conventional methods of construction. While the earliest projects using nuclear explosives may not have to meet these severe economic criteria (as the development cost of experimentation with a new technique can be amortized over a number of subsequent applications), the use of nuclear explosives must show promise of significant superiority for some purpose before one will be willing to undertake the expensive empirical studies required to learn precisely how to apply the technique.

According to figures released by the U. S. Atomic Energy Commission, a nuclear explosive in the range of a few kilotons or a few tens of kilotons of energy yield can be provided for about $500,000. For this price the AEC will supply the explosive and detonate it, and will be responsible for the radiological protection of the public. The user will be expected to furnish a cased emplacement hole of appropriate depth. When everything is taken into account, the cost of exploding a 10-kt nuclear explosive at a depth of 1,200 feet would be of the order of one million dollars.

In discussing projects of this nature it is important to recognize several facts. First of all, no proposal for the use of nuclear explosives on a small scale can possibly compete with conventional methods. Secondly, the cost of a nuclear project increases quite slowly with the energy release, and hence

the economics of the nuclear technique becomes rapidly more favorable as the size of the required explosive increases. Indeed, if a megaton explosion should be appropriate, the explosive could be supplied, emplaced, and detonated for $1,000,000, only twice the fee for a 10-kt explosive. A larger hole would be needed, of course, and the required depth of burial of the explosive would be greater, but the cost of the associated construction would be multiplied by a factor far smaller than the 100-fold increase in the size of the resultant nuclear explosion. Thirdly, most of the possibilities for the use of nuclear explosives in water resource development are in the nature of capital improvements. The immediate gains may not be striking, but the sum total of significant annual benefits over the long life of the development can be large.

In summary, then, we at the Lawrence Radiation Laboratory believe that there are ways in which nuclear explosives can be used to assist in the development of the nation's water resources. Some of these may prove economical. However, we need the help of experts on water resources in developing actual projects. Our function is to provide technical information about the tool

nuclear explosives and to analyze, evaluate, and predict its effects. We submit this note in the hope that the people and the organizations responsible for our country's water development will utilize this potent new technique.

LEGAL NOTICE

This report was prepared as an account of Government sponsored work. Neither the United States, nor the Commission, nor any person acting on behalf of the Commission:

A. Makes any warranty or representation, expressed or implied, with respect to the accuracy, completeness, or usefulness of the information contained in this report, or that the use of any information, apparatus, method, or process disclosed in this report may not infringe privately owned rights; or

B. Assumes any liabilities with respect to the use of, or for damages resulting from the use of any information, apparatus, method or process disclosed in this report.

As used in the above, person acting on behalf of the Commission " includes any employee or contractor of the commission, or employee of such contractor, to the extent that such employee or contractor of the Commission, or employee of such contractor prepares, disseminates, or provides access to, any information pursuant to his employment or contract with the Commission, or his employment with such contractor.

UNDERGROUND NUCLEAR DETONATIONS

by G. W. Johnson, G. H. Higgins, and C.E. Violet

Lawrence Radiation Laboratory, University of California

Livermore, California

July 8, 1959

Summary

Since 1952 eight nuclear explosions have been fired underground at the Atomic Energy Commission's Nevada Test Site. The explosions have varied in energy release from 55 tons to 19,000 tons of TNT equivalent and were carried out at depths varying from shallow burial to produce cratering to those depths at which no visible effects appeared on the surface, The major experimental data from these explosions, as well as the phenomenology of the deeper shots, is summarized here.

1. Introduction

During the 1955 nuclear weapons test series in Nevada it became increasingly clear to the Lawrence Radiation Laboratory that concern over fallout would be a serious limitation on future weapons tests. Therefore, based on a suggestion of Griggs and Teller [1956], consideration was given to the possibility of testing underground at such depths that there would be no escape of radioactivity to the atmosphere. Further detailed consideration led to the design of an experiment, code-named Rainier, to test the feasibility of containment of the radioactive debris from a nuclear explosion. This experiment conducted on September 19, 1957 was completely successful and all objectives of the experiment were achieved. The results of this 1.7-kiloton detonation have been previously reported in considerable detail [Johnson and others 1958, Johnson and Violet 1958, Diment and others 1959]. Its continued study has led to a fairly complete understanding of the physical and chemical processes associated with underground nuclear explosions. Subsequent to the Rainier detonation, five additional nuclear devices were fired underground at the Nevada Test Site during October 1958 in connection with

*

Work was performed under the auspices of the U.S. Atomic Energy Commission.

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weapon development programs. The preliminary results of these later explosions have been published [Johnson and Violet 1958].

In this paper all major results presently available from these shots, as well as three earlier cratering shots, are summarized and the phenomenology of these events is discussed.

2. Experimental Conditions

All of the explosions, except the earlier cratering shots, took place in a thick formation of bedded tuffs. The three exceptions, which were detonated in a lightly cemented alluvium, will not be described in detail but are included for completeness. The coordinates and time of detonation for each explosion are listed in Table 1.

The geological structure in which the deep shots took place is characterized by 250 feet of welded tuff under which is 1700 feet of bedded tuffs and a thick bed of dolomite [Diment and others 1958a]. The locations of the several shot points are illustrated in Figure 1. The details of the tunnels and stemming for each event are shown in Figures 1 through 8 of the Appendix. A stratigraphic feature of some importance in interpretation is the loosely consolidated zone in Tos,, the limits of which are indicated by dashed lines