TOPIC OUTLINE
AC&SSIO4"oductionPo REGISTR
a, iancmpLp ci? nuclear excavation
b. Project Plowshare
c. Test program
3. Nuclear excavation phenomenology
a. Crater formation
b. Physical relationships
c. Cratering experiments
1.. Nuclear excavation advantages
a.. IExplosive costs
b. Placement costs
c. Cost of operations
d. Time
e. Convenience
5. Nuclear excavation disadvantages
a, Size of project
b. Radioactivity
c. Fallout
d. Air blast
el Ground shock
6. Proposed projects
a. Project Chariot
b. Panama Canal
c. Project Carryall
d. Tennessee-Tombigbee Rivers
7. Future of nuclear excavation
a. Test ban treaty
b. International agreements
co State of the art
8. Conclusions
C9A Fr S LEA O' K W
ACCESSION NOPO REGISTR___
A CGSC FT LEAVEN WORTH KAL
i. PURPOSE. The purpose of this study is to examine
the state of the art of nuclear excavation and assess its
problems and potentialities for future construction projects.
2. INTRODUCTION. Chemical explosives have been used
in excavation projects for many years. Generally, they are
used to loosen and break up material which can then be moved
by mechanical means. The cost of such projects increases
with the amount of earth to be moved and the times involved
may be exceedingly long.
The atomic age has brought about a dramatic, new, earth-
moving device. Nuclear explosives, placed a certain dis-
tance underground, can be used to loosen and expel huge
volumes of earth in a single operation. During the 1956
Israeli-Egyptian conflict, the Suez Canal was closed. Dr.
Harold Brown, then director of the University of California's
Livermore Laboratory, conceived the idea of using nuclear
explosives to blast a new canal across the Sinai peninsula.
(1: p. 2,) This plan was dropped, but the general idea of
using nuclear explosives for excavation was formalized into
Project Plowshare.
Project Plowshare, formed in 1957 under the auspices
of the Atomic Energy Commission, is dedicated to the task
of conceiving peaceful uses for atomic energy. In 1959,
the Corps of Engineers and the Atomic Energy Commission were
assigned joint responsibility for developing nuclear exca-
vation technology. (2: p. 313.) The Corps of Engineers
also has construction responsibilities, under its civil
works functions, to which nuclear excavation techniques are
applicable.
An extensive nuclear excavation test program was planned
under Project Plowshare. Several nuclear cratering shots
were fired in order to develop required technology, but the
program suffered several setbacks. The self-imposed nuclear
testing moratorium, from 1959 to 1962, seriously inconven-
ienced the program. The present nuclear test ban treaty has
slowed Project Plowshare considerably. (3: p. 1153.) The
future of the nuclear excavation program is somewhat uncer-
tain, thus it seems worthy to make an appraisal of its
accomplishments and potential.
3. NUCLEAR EXCAVATION PHENOMENOLOGY. In order to
evaluate the use of nuclear explosives for excavation, a
basic understanding of the phenomena involved is required.
The simplest type of excavation is the formation of a cir-
cular crater with a single point charge. There is more to a
crater than a hole in the ground. Crater formation and the
parameters involved were studied extensively by the military
during World War II. (4: p. 6.) Most of the work was con-
ducted with chemical explosives and much of it can not be
extrapolated to nuclear charges.. Nuclear charges have energy
concentrations and rates of detonation much higher than those
of chemical explosives.
The size and shape of a crater varies with the type of
soil, the depth of burst, and the yield of the charge. When
a nuclear explosive is detonated beneath the surface, a tre-
mendous amount of material is ejected upward and outward.
Some of the material falls back into the hole. This partial
refilling of the hole results in an apparent crater rather
than the full or true crater. Under fixed conditions, there
is an optimum depth of charge burial which will maximize
the size of the apparent crater. Experiments with chemical
explosives have shown that the diameter and depth of apparent
craters can be predicted quite accurately.
Scaling laws have been developed for nuclear charges,
but they are not as accurate nor do they cover as many con-
ditions as those for chemical charges. There has been only
one full-scale nuclear excavation experiment under the Plow-
share Program.' This was the 100-kiloton Sedan event fired in
the Nevada desert in 1962. The test was very successful and
produced a spcctacular crater 1200 feet in diameter and 320
feet deep. (5: p. 50) Several other nuclear cratering
experiments have been performed, but the yields involved have
been on the order of 1 kiloton or less.
Only single nuclear detonations have taken place. No
tests have yet been carried out with a row of nuclear charges,
although this has been done with chemical charges. The chem-
ical tests have shown that a long continuous ditch can; be
achieved through proper spacing of the charges. It is assum-
ed that nuclear charges will behave in a similar manner. A
row of nuclear devices could then be detonated to excavate
cuts, channels, or ditches, applicable to a variety of cony
struction projects.
L[... NUCLEAR EXCAVATION ADVANTAGES. For nuclear exca-
vations, the cost per cubic yard of earth removed goes down
as the amount of earth removed goes up. The cost, using
chemical explosives and mechanical earthmoving devices, in-
creases with the amount of earth to be moved. At some point,
nuclear excavation becomes more economical than conventional
means, providing the project is sufficiently large.
A kiloton of nuclear explosive power will excavate
approximately 100,000 cubic yards of material at a cost of
about $500 a yard. (6: p. 3.) A megaton project would
cost only about >.03 a yard. (1: p. 4b.) Conventional ex-
cavation costs vary from I.50 to several dollars a cubic yard.
It is readily apparent that nuclear explosives offer a def-
inite cost advantage for large excavation projects such as
canals, harbors, mountain cuts and dams.
The cost of chemical explosives incueases directly with
the amount used., This is not true of nuclear explosives.
The Atomic .nerdy Commission has announced prices of $350,000
for a 10 kiloton device and 0600,000 for a 2 megaton device.
(7: p. 3.) A 200 fold increase in explosive power increases
the cost of the explosive by a factor less than two.
Placement costs for nuclear devices will be significant-
ly lower than those for chemical explosives. A kiloton nuc-
lear device requires a placement hole less than 3 feet in
diameter. A similar amount of TNT would make a sphere 34.
feet in diameter. (6: p. 18.) Considerably larger nuc-
lear charges could be placed in about the same size hole.
Larger chemical charges would require larger and more costly
placement excavations.
Cost savings would also be achieved in the actual oper-
ations using nuclear explosives. Less equplment and fewer
personnel would be required, since the earthmoving task is
accomplished by the explosive itself.
Nuclear excavation techniques can result in significant
time savings. $ince it is essentially a one-step process,
the only time required is that needed to emplace and detonate
the explosIve. For very large projects, time savings might
well be measured in years. Such savings in time could have
important strategic implications for certain projects vital
to the nati ons needs.
In some situations, it may just be more convenient to
use nuclear excavation. A situation might exist where it is
almost impossible to use conventional methods. The area may
be inaccessible to earth moving equi>ment, but may readily
allow the emplacement of nuclear explosives.
S. NUCLEAR EXCAVATION DISADVANTAGES. Nuclear excava-
tion is generally feasible only on very large projects. Con-
ventional means are more economical for most ordinary ccnstruc-
tion projects. The cost of the smallest nuclear device would
still be several hundred thousand dollars.
All nuclear explosions generate radioactivity. Fission
explosions derive their energy from the break-up of heavy
elements such as uranium and plutonium. The resulting debris
is radioactive. Fusion explosions join together smaller
particles to form a helium nucleus. No radioactive by-prod-
ucts are formed in this process. Unfortunately, no way is yet
known to make a nuclear device entirely fission-free. Devices
consisting of 5%'or less fission energy can be made, and
attempts are underway to further minimize this percentage.
(1: p. 5.) Even if a 100% "clean" device was used that is,
one deriving all its energy from fission, the neutrons re-
leased would still induce some radioactivity in the surround-
ing soil.
Radioactivity will always be a disadvantage to the use
of nuclear explosives for excavation. The extent to which it
can be predicted and controlled will help to determine its
relative disadvantages for a specific project. Most of the
radioactive products are promptly distributed over an area
downwind from the site as fallout. Using the relatively
"clean" devices presently available, this area of significant
fallout can be contained in a distance of 30 miles or less.
Forecasts are that future progress in the technology could
reduce the danger zone to less than 5 miles. (7: p. 3.)
A small amount of radioactive debris remains in the
atmosphere for a considerable period of time. Some of these
radioactive particles tend to concentrate in certain plant
and animal life. Some long-lived particles, such as Stron-
tium 90 and Cesium 137, may cause hazards to man when they
become concentrated in foods, such as milk. Before any
nuclear excavation can take place, extensive studies will
have to be made to insure that the risks involved from radio-
activity, and its biological consequences, are acceptably
small.
Air blast and ground shock are other undesirable effects
of nuclear explosions. A chemical explosion and a nuclear
explosion of the same size would produce the same blast and
shock, but because much larger nuclear charges would be used,
the effects will be correspondingly larger.
The intensity of the air blast depends upon the depth
of burial of the charge, atmospheric conditions and the
terrain. Attenuation of the air blast increases with depth
of burial. Certain atmospheric conditions and terrain con-
figurations can reinforce blast waves so that significant
damage can occur several hundred miles away from a large
nuclear explosion. (6: p. 39-)40.)
The distance to which ground shock carries is dependent
upon the nature of the ground in which the explosion takes
place. EExtensive geological surveys would have to be carried
out in order to predict the extent of damage from earth motion.
Except for radioactivity, the disadvantages of nuclear
explosions are due only to the large amount of energy re-
leased at one time, as opposed to that from smaller chemical
explosions. The effects of radioactivity, however, produce
the most significant disadvantage.
6. PROPOSED PROJECTS. The expected efficiency and
economy of using nuclear explosives have resulted- in proposals
for several spectacular excavation projects.
The first, Project Chariot, was intended to excavate a
harbor in Alaska as a part of the Plowshare program. (6: p.67.)
It was to be the first full-scale excavation using several
nuclear explosives simultaneously detonated. It envisioned
the use of a 200-kiloton device to form a large basin and four
20-kiloton charges to link the basin with the sea. Extensive
geological and bioenvironmental surveyls were made starting
in 1959. Detailed studies were carried out on fallout pat-
terns.,and blast and shock predictions were made.
Many individuals and. groups of interested persons be-
gan to express reservations about the possible consequences
of the radioactive fallout from the detonation. (1: p. 9.)
Studies showed that radioactive fallout concentrated in
lichens, which is food for caribou. (7: p. 3.) Caribou
meat is an important part of the Eskimost diet. It has been
found that caribou meat from Alaska contains higher radiation
levels than that found in cattle which graze the Nevada test-
ing grounds.
Project Chariot came very close to being carried out,
but an Atomic Energy Commission press release on August 24, 1962
stated, "The Chariot experiment has been shelved, not because
of the possible biological impact, but: because it has been
overtaken by events. From a technical standpoint ... much
of the experimental data have now been obtained or soon will
be from experiments in Nevada." It appears that this an-
nouncement may have been overly optimistic. The Sedan event
of July l962provided much useful data, ,but the experience
of detonating multiple nuclear bursts, which would have been
obtained from Project Chariot, has never been realized.
The most publicized nuclear excavation proposal is un-
doubtedly that for a new Panama Canal. The recent U.S. -
Panama altercation focused attention upon the inadequacies
of the present canal. It can no longer handle many of the
world's ships and the complicated lock system makes it ex-
tremely vulnerable.
It is estimated that a sea-level canal could be blasted
across the isthmus, with nuclear explosives, at one-tenth the
cost of using conventional means. (8: p. 55.) The time re-
quired could be cut in half. A total of 300 nuclear explosives,
detonated over the 48 mile long Sasardi-Morti route in Pan-
ama, would result in a canal 1000' wide and cost about 500
million dollars. (9: p. 149.) Using conventional methods,
the mere conversion of the present canal to a sea-level canal
would cost over 2 billion dollars. (3: p. ll54.)
There is no doubt, even if the figures contain some un-
certainties, that excavation of a new Panama Canal, by nuclear
means,' would save money. The cost, however, may not be the
primary consideration for construction. The new Panama Canal
must traverse an independent country. The U.S. would have to
obtain permission'to construct the canal. The task of selling
nuclear excavation to a foreign government may be a difficult
one. The benefits would have to far exceed the risks, and the
inconvenience to the people in the Immediate area. They may
feel that a new canal really (only' benefits'the United States.
The best place to conduct a nuclear excavation project
would be in the United States. This would avoid political
considerations, other than those of the test ban treaty which
will be discussed later. A safe and successful detonation
would greatly enhance the nuclear excavation program in the
eyes of the world.
Two major projects have been proposed for the continental
United States. Project Carryall is a proposal to blast a cut
through the Bristol Mountains in California. (10: p. 3'6. )
The relocation of the Saria Fe Railroad and U.S. Highway 66
through the cut would result in substantial savings. The
area is virtually uninhabited and construction by conventiona-
means is almost impossible.
The future of Project Carryall is uncertain at this time.
Because of the interstate highway timetable, construction of
a bypass route for U.S. 66 must be started by 1968. (1: p. 12.)
Although the railroad has no time schedule, the project may not
be as inviting without the highway.
The second U.S. project has been proposed by officials
of Tennessee, Alabama, Mississippi and Kentucky. (11: p. 1L[.)
This project entails nuclear excavation of a 40-mile section
of a 253-mile waterway connecting the Tennessee River with the
Tombigbee River. The Corps of Engineers has conducted a
study and estimated the cost of the project using convention-
al means. Studies, considering the use of nuclear explosives,
have also been initiated.
Nuclear excavation is arplicable to a wide variety of
construction projects. Nuclear scientists desire to Drove
that their work can aid mankind rather than injure it. They
would like to remove the stigma of Hiroshima and Nagasaki by
performing worthwhile projects using nuclear explosive energy.
It is a paradox that nuclear excavation, a technique which
can most dramatically prove the benefits of a nuclear ex-
plosion, may not be allowed to occur.
7. FUTURE OF NUCLEAR EXCAVATION. If the present test
ban-treaty remains in effect, peace-serving excavation with
atomic explosives may never be conducted. The treaty forbids
explosions which cause radioactive debris outside the terri-
torial limits of a signatory nation. It specifically pro-
hibits nuclear bursts in the atmosphere. Although the treaty
does not prevent underground bursts, cratering shots are not
strictly underground.
Unfortunately, the present treaty is very vague as to
what constitutes a violation. The amount of debris which
can escape the borders of the country conducting the test has
not been specified. (12: p. 33.) A violation may then de-
pend upon the effort expended to detect the radioactive debris.
The U.S. has postponed all large scale cratering experiments,
as these might antagonize the Russians.
If sufficient progress is made in developing the low
fission-to-fusion ratio, nuclear excavation experiments free
of both diplomatic and radioactive fallout can eventually be
performed. It may be possible, at an earlier date, to amend
the present treaty to allow nuclear excavation tests. It
would not be too difficult, however, to use nuclear exca-
vation tests as a cover for military weapons testing, unless
some type of inspection system was instituted. The Soviets
are certainly interested in nuclear excavation. It may be
possible to work out mutual agreements or even cooperative
testing. Any change to the test ban treaty would have to be
agreed upon by the other signatory countries.
Additional large scale cratering experiments must be
carried out before the feasibility of using nuclear explosives
can be conclusively proved. Dr. Glen T. Seaborg, chairman of
the Atomic Energy Commission, estimates that it would take
five years and six or seven more tests to engineer a nuclear
device capable of being used in a project such as the Panama
Canal. (1: p. 3.) This time could probably be reduced if
additional effort and resources were expended.
8. CONCLUSIONS. The use of nuclear explosives in large
scale excavation projects can result in significant savings
in money and time.
There are many construction projects, conducive to the
use of nuclear excavation techniques, which would substan-
tially benefit mankind.
Considerable progress has been made in reducing the
amount of radioactive fallout from nuclear cratering deton-
ations and more progress is indicated.
10
Additional testing must be carried out to prove con-
clusively the feasibility and safety of nuclear excavation
techniques.
The people of the world must be shown that the biological
and physical risks/ inherent in nuclear explosions, are
acceptably small.
International agreements or amendment to the test ban
treaty will be required to carry out any large scale crater-
ing tests in the near future.
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BIBLIOGRAPHY
1. Friedlander, Michael, "Nuclear Digging," Scientist andCitizen, VII: No. 1, November l964.
2. Circeo, Capt. Louis J., Jr., " ngineering Propertiesof Nuclear Excavations,". The Miltary ngineer,September-October 1964..
3. Science, 13 March 1964.
.4. Johnson, Gerald W", "Excavation With Nuclear Explosives,"University of California Report, UCRL-5917,November 1, 1960.
5. Kelly, John S., "Moving Earth and Rock with a NuclearDevice," Science, 5 October 1962.
6. Proceedings of the Second Plowshare Symposium, Univer-sity of California, Lawrence Radiation Laboratory,Livermore, California and San Francisco OperationsOffice, USAEC, TID-4500, -May, 1959.
7. Ewing, Ann, "Dig With Nuclear Energy," Science NewsLetter, January 2, 1965.
8. Life, March 6, 1964..
9. Science News Letter, September 5, 1964.
10. Circeo, Capt. Louis J., Jr,, "Nuclear ExcavationApplications," The Military engineer, November-December, 1964.
11. U.S. News and World Report, May 20, 1963.
12. Finney, John W., "The Biggest Building Job of All Time,"Sciene Di est, July, 1964.
13. Johnson, Gerald W., "Industrial and Scientific Appli-cations of Nuclear Explosives," University of Cal-ifornia Report, UCRL-5840, January 19, 1960.
14.. U.S. News and World Report, June 10, 1963.
15. Newsweek, January 18, 1965.
16. Engineering News Record, December 6, 1962.
17. Department of State Bulletin, June 25, 1965.
18. Science News Letter, February 9, 1963.
19. Business Week, May 18, 1964.
20. Galton, Lawrence, "A New Canal - Dug by Atom Bombs,"New York Times Magazine, September 20, 1964.
21. Time, February 8, 1963.
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