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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