Nuclear Fracking in 1973 and Excavation Gigaton Device Damage Radii And Space Colonization In Nuclear Caves

A guest article by Joseph Friedlander

When researching the Plowshare article for this post
I ran across this 1973 state of the art summary

 about nuclear chimney stimulation of gas and in situ oil shale mining and for many other uses.  Note some of the pictures to aid local state authorities in planning for damage claims.

Damages (radiation earthquake financial and otherwise) are what stopped some of the serious application of the much more economical megaton and eventually gigaton devices.  For example if you could fully utilize the heat of a gigaton device and it cost $10 million (12 tons of deuterium cost $6.06 million at 500 dollars a kilogram) it would be the equivalent of many billion dollars in coal. Even wastefully applied you could cook vast beds of minerals, possibly having preinjected fluids to aid in the digestion of the resource. But as you will see that would work a lot better on a planet that was basically deserted. I can see using these things to seriously mine Mars, for example. But on Earth—people can sue if you break their windows.

Seismic damage ranges of typical underground explosions is the first picture. Note that 150 miles radius is the minimum to be absolutely sure there are no damages from a megaton device on a sensitive day (atmospheric lensing of shock) 6 kilometers or 10 miles might be a totally safe distance from a kiloton device, and from a gigaton device –what?–1000 or 1500 miles radius might be the minimum.  So no Swiss government is ever going to set off a gigaton engineering shot say 30 kilometers down in the Alps (hypothetically you could get it there by a crust melter probe that ALSO cooled the hellish device within)  because it would probably rattle most of the windows in Europe and break every window in Switzerland. Do that in winter and you will be rather unpopular (It would probably take several years to replace even most of them)

The Source Files and the search that got me there:
Plowshare technology assessment : implications to state governments : final report
by Whan, Glenn AWestern Interstate Nuclear Board

Published 1973
Topics Project Plowshare (U.S.)Underground nuclear explosionsNuclear excavation


From  LLNL-CONF-415308 
Edward Teller Biographical

 S. B. Libby, A. M. Sessler
 August 4, 2009 
about the Plowshare project

technically the results were very positive. One Utah test, in 1967, called Gasbuggy,
increased gas production by a factor of six, another test, in Colorado, in 1969,
called Rulison, increased well production by a factor between 10 and 15.
Again, public concern about radiation (in this case quite unfounded) brought
the activity to a halt

Very large mushroom clouds can reach the stratosphere– this is for a surface detonation. Even a deeply buried gigaton device would probably throw up dust plumes to nearly 50 km.

The Sedan shot did this

 The fusion-fission blast had a yield equivalent to 104 kilotons of TNT (435 terajoules) and lifted a dome of earth 90 m (300 ft) above the desert floor before it vented at three seconds after detonation, exploding upward and outward displacing more than 11,000,000 t (11,000,000 long tons; 12,000,000 short tons) of soil

So a 104 megaton device would (simple cube dosen’t really scale exactly but this is back of the envelope) would move about 11 billion tons of earth, and a gigaton device 110 billion tons, about 30-40 cubic kilometers. A pity it would be radioactive…

Sedan shot resulted in a radioactive cloud that separated into two plumes, rising to 3.0 km and 4.9 km (10,000 ft and 16,000 ft).
A gigaton device or better would be like a supervolcano, topping out from the high 30 km to up to 45 or even higher.

A circular area of the desert floor five miles across was obscured by fast-expanding dust clouds moving out horizontally from the base surge, akin to pyroclastic surge.

A excavation gigaton device then could sweep a dust and rock storm across sixty miles or 100 km. Thirty miles in your rear view mirror and you are still in danger. Wow.

The explosive device was lowered into a shaft drilled into the desert alluvium 194 m (636 ft) deep.The resulting crater is 100 m (330 ft) deep with a diameter of about 390 m (1,280 ft). 

So an equivalent excavation gigaton device would be buried several kilometers deep and even then would give a crater over a kilometer deep (even pushing a mile deep) and with a diameter of well over 5 kilometers. Wow again. That’s the crater, dude. Actually, that’s the apparent crater, the bottom of that crater hides the deeply buried real crater. You could drill through a mountain range with a row charge of these at who knows what cost to the planet’s ecology.

The blast caused seismic waves equivalent to an earthquake of 4.75 on the Richter scale The radiation level on the crater lip at 1 hour after burst was 500 R per hour (130 mC/(kg·h)), but it dropped to 500 mR per hour after 27 days.
Within 7 months(~210 days) of the excavation, the bottom of the crater could be safely walked upon with no protective clothing,with radiation levels at 35 mR per hour after 167 days.

Assuming just one fission trigger and staged D-D fusion without spark plugs from that point with a lead radiation casing, the fission products would be about the same amount as this Sedan event shot, but over a far bigger area so ironically the fission products would be far more dilute. But the activation products from a gigaton of D-D fusion! Strongly recommend boron around the device to absorb neutrons or you’ll be sorry….

The chart below extrapolated runs into strength of  materials limitations– there are limits to how big a cavity void or  ‘nuclear cave’ you can make that will not collapse under the stress of the roof arch.  Like a retarc (crater spelled backwards, bulging up of the surface without a dome burst to cause an actual crater), there is a limit to the size you can do it.

A retarc is shown about 3:48-4 minutes into this movie 0800035 – Nuclear Excavation, Excavating with Nuclear Explosives – 1968

 Otherwise a sufficiently deep many gigaton shot row charge could throw up a mountain range at will— just the sort of insane thing that a supervillan would do in the comics to stop 3 patrol cars chasing him.  Hm.

You could probably in very competent rock have a top of rubble chimney void ‘nuclear cave’ up to the size of the biggest natural cave rooms, a couple hundred meters across. (Remember the thing has to survive not just a static load but the dynamic load of actually being formed.)  That is megaton sized, not gigaton. Otherwise you could make a underground cavern kilometers across.

The nuclear cave formed by the Gnome event–3 kilotons not 3 megatons or 3 gigatons made a cavern 170 feet across 90 feet high. Typically such a cavern represents the uncollapsed void on the top of a rubble chimney.

 I am wondering if in microgravity or on a small asteroid simply putting a bomb in the (competent, joined rock) core would be enough to puff it up and it would freeze into a giant spherical colony hull by itself. If so it would be a sphere around the original explosion point, smaller than the rubble chimney portrayed above.

 Maybe on the Moon you could make a multi kilometer colonizable cave at exactly the spot you want without being dependent on natural lava tubes (which certainly exist there). I am guessing on Ceres you could use gigatons in very competent and cold rock. (In real life there is so much water there that major steam emissions might result).  But any body that size or smaller should be able to make an instant dome– or not if you have structural failure. I think though there would be a major learning curve, and anyway to start you would want people within eyeshot and emergency running radius in case of an emergency decompression event (blowout) and that argues for a megaton sized under 300 meter fused-sealed nuclear cave and work your way up from there.  These devices really are more for use in space than Earth, always supposing the radiation problem can be licked.

Another use for multi-megaton, not gigaton bursts might be to heat seal such a cavern against cracks that could lose air when it formed. The dripping liquid rock  from the roof in a lunar nuclear  cave  would make it look extremely creepy, though as it froze– Stalactites in vacuum.. Welcome to the Batcave!

If you had abundant water available part of me is wondering about using the water in a sea cave like corridor for an impromptu airlock.  In case of a a leak it would tend to sublime and if you design a cold trap multi W shaped exit correctly it would form an ice plug. Even if the bottom of the cave was very uneven you could have a floating colony inside and swimming like in a sea cave.

So you would swim like a frogman to get to the outer space environment, since you are wearing oxygen tanks and a suit anyway. Then you would go in the (hopefully intact) real airlock and sublime the water out and do your tasks outside.

To contain a 10 megaton device it would have to be over a mile underground, 100 megatons over two miles, a gigaton range device would advisably be nearly 10 km or 6 miles down.  It would fracture strata under a whole county. The seismic event would be noticable throughout a good size state or country.
Below is a picture comparing the various AEC gas stimulation shots and quotes from the work about Nuclear Fracking , the state of the art in 1973.

“September 1973.” p40-45 table  statson —Project Rulison
also a gas stimulation experiment, was conducted on September 10, 1969.
Participating in this project with the AEC were the Austral Oil Company and
CER Geonuclear Company. A 40-kiloton nuclear device was detonated at a
depth of 8425 feet, 15 miles southwest of Rifle, Colorado. The total gas
production from this experiment has been 455 million cubic feet, and the
estimated potential gas recovery over a 30-year period is about 6 billion
cubic feet (the average potential production of nearby conventional wells
is 260 million cubic feet)
An analysis of material resources has shown that the need for uranium-235 and plutonium-
239 for this proposed natural gas stimulation program could be as much as
5% to 10% of the requirements of the civilian power program. 
 Limitations on the supply of special nuclear material for nuclear explosives may well
prohibit a rapid commitment to natural gas stimulation in spite of the
demonstrated need.

In fact, the amplitudes of surface waves from earthquakes are
several times larger than those from underground nuclear explosions.
Also, earthquakes are more damaging because the energy release lasts for
a longer period of time (seconds to minutes) , whereas the energy release
time for a Plowshare explosion is less than a second. Therefore, a
nuclear explosion of Richter magnitude five does not have the same potential
for causing, through ground motion, damage and injury as does an
earthquake of Richter magnitude five.

The worst geologic composition for the creation of large amounts of
surface gound motion would be a detonation area surrounded by granite or
other “hard” rock out to a relatively large distance (greater than five
miles) . This configuration allows the seismic waves to propagate with
little energy loss over a large distance. If there are geological discontinuities
some distance away from the detonation area located on alluvium
or other “soft” rock, significant surface motion will then occur
in this region. Thus, an area which may seem far away, twenty to thirty
miles from the point of detonation, may not be free from potentially
damaging ground motion.

Ground motion thresholds for various types of damage to structures
have been well documented in the literature.Upon superimposing
these thresholds on a graph of predicted ground motion for a typical Plowshare
project, the relationship between expected damage and distance from
ground zero for various explosive yields can be demonstrated (Figure
V-2) .
Uncertainties in both the damage thresholds and the predicted
ground motion limit this diagram to only qualitative trends. Actual
damage predictions must be made for each specific Plowshare project at a
particular location. Such a diagram, however, serves to demonstrate that
minor “architectural damage” (cracking of plaster, disturbance of bricks
and concrete blocks, etc.) can be expected to occur 10 to 20 miles from a
typical Plowshare detonation.The Rulison detonation resulted in 337 damage claims settled for a
total of nearly $135,000 of which $97,570 was for property damage.

The other $37,000 was for losses such as lost production time in nearby mining
operations. The majority of claims were for brick chimney damage and
cracked interior plaster. The dollar damage to structures came within 88%
of the predicted damage.

In anticipation of the Rio Blanco experiment, an extensive inventory
and hazard assessment was made for structures out to a distance of 30 miles;
these included buildings, bridges, tunnels, power and telephone lines, gas
and oil and water pipelines, mines and quarries, railroads, hydraulic structures,
airports, and roads. On the basis of this investigation, structural
bracing and modifications were carried out prior to shot time. The unavoidable
damage to approximately 170 structures in the area was estimated to be
about $50,000. After the actual detonation, however, structural seismic
damage appears to be much lower than the maximum estimated. As of June 15,
1973, 72 claims had been settled at a total cost of $13,425. For the
Wagon Wheel experiment, preliminary indications are that the sequential
detonation of five 100 kiloton explosives could cause minor architectural
damage to about 200-400 residential, public, and commercial structures and
1 8 associated buildings for which repair costs could be about $65,000.

Possible Earthquake Stimulation by Seismic Waves
No relationship has yet been established between underground nuclear

It is expected that an explosion
in the one hundred kiloton yield range would generate no more than
a few dozen aftershocks, none of which would have a Richter magnitude of
greater than 3.0 (compared with a Richter magnitude of 5,5 for the original
explosion). The aftershocks should cease within a few hours, and the
total seismic energy released in all these shocks would be substantially
less than that from the original one hundred kiloton a 100
kiloton, all fission explosion with material efficiency of 30%, about 13
kilograms of nuclear fuel (about 800 curies for plutonium) remains behind
after the detonation.
It has been reported that from 5,000 to
20,000 curies of residual tritium per kiloton of explosive energy is produced by a fusion device.

The energy yield of a fission explosive is achieved through the fission
or splitting of trillions upon trillions of individual nuclei. The
fission of 1.45 x 10e23 nuclei of a suitable fissionable material will result
in the release of 1 kiloton of explosive energy.

In rock with a lithium content of 30 parts per million (by
weight) some 1 to 3% of the neutrons which escape the explosion will produce tritium.
Fenske estimates that sorption alone will decrease the concentration
of long-lived nuclear reaction products such as strontium-90 and cesium-
137 by seven orders of magnitude before they can move outside the explosion zone. (Explosion zone is defined as the rubble chimney and fractured area immediately surrounding.) The effect of sorption on tritium
is usually neglected; tritium will generally move almost as fast as ground
water in the form of tritiated water or tritium dioxide.

With the exception of the possible use of nuclear explosions for water
management, ground water migration in the vicinity of most industrial Plowshare applications is extremely slow (200 to 800 feet per year) .

Radioisotopes such as strontium-90 and cesium-137 are strongly sorbed by
rock surfaces; therefore, the migration of these contaminants will be even
much slower than the flow of ground water. As previously noted, sorption
of tritium will be negligible, and it will move at about the same rate as
ground water. Even assuming no sorption, or dispersion, however, Fenske
calculates that the concentration of tritium in contaminated water, from
an underground 1 megaton all fusion explosion, moving at a flow rate
of 100 meters per year would be below the maximum permissible concentration
(mpc) in drinking water before the water could move 8.8 miles from
the explosion zone. Similar calculations predict tritium concentrations
below mpc values at a water well 6.5 miles from the Rio Blanco project.
It is also of interest to note that, after 14 years of underground testing
of nuclear devices at NTS, no radioactivity above normal concentrations
has been detected at any springs or wells in Nevada.

Product Contamination : Radioactive contamination of the end product
of an industrial Plowshare project (e.g., natural gas, geothermal steam,
copper ore, etc.) will of course depend upon the particular application.
The two radionuclides of principal concern in product contamination for
natural gas stimulation are krypton-85 and tritium. Both are present in
sufficient quantities and have long enough half-lives to pose a hazard.
It is generally assumed that the gas released by this method will be consumed,
at least partially, in individual households. Two hypothetical
studies have been made to evaluate gaseous product contamination – one for
29 30 Gasbuggy and the other for Rulison.  The study for Gasbuggy predicted
a maximum exposure from contaminated natural gas of 2.2 mrem/year for residents
of Los Angeles and 2.5 mrem/year for residents of San Francisco.
The calculational model used for Rulison indicated that the total
potential dose that an individual would receive in a home in Grand Valley,
Colorado, from an unvented gas stove and refrigerator operated with nonflared
gas piped from the project would be 39 mrems the first year, would
decrease to about 5 mrems the second year, and would decrease correspondingly
after that. 

The same study estimated that the total dose an individual
in Grand Valley would receive from the same appliances using gas
taken from the Rulison well after the operational flaring of some 400 million
cubic feet would be .03 mrems the first year and even lower doses in
following years. The AEC has noted with respect to both cases that such
conditions are hypothetical and are not representative of possible large
scale future gas distribution from nuclear stimulated wells

 Gas from a new well would probably be diluted with gas from older wells in which the
radioactivity would be at considerably lower levels. Because of this
dilution factor, it is currently thought that no flaring of gas from a
new well would be necessary prior to its being connected to the distribution
In general, normal Plowshare operations would probably increase background
radiation in the vicinity of a project site less than two percent.

All nuclear devices will remain at all times under the possession and control of the AEC. 
Article I of the
Treaty on the Non-Proliferation of Nuclear Weapons, to which the United
States is a party, prohibits the United States from transferring control
over nuclear explosive devices “to any recipient whatsoever. “
 In R&D
Plowshare projects, the actual handling, emplacing, and detonating of
nuclear explosive devices is done by AEC “contractors” — companies other
than the industry sponsors, operating on a cost-plus basis on behalf of the
AEC under tight security and other government controls. A similar arrangement
is contemplated for the commercial Plowshare phase: emplacement and
detonation of nuclear devices will be performed by the AEC through its
“contractors,” as a service offered to industrial “users” for a fee.
the present R&D phase of Plowshare, the regulatory machine of the AEC
is not involved in the planning and carrying out of Plowshare projects.
Instead, because the nuclear devices remain at all times in the possession
and under the control of the AEC itself, through its contractors, Plowshare
projects are considered “operational functions” of the AEC.

Governor Hathaway of Wyoming
indicated that the main problem with Project Wagon Wheel is that El Paso
Natural Gas has not sold the local people on the idea properly. A twoyear
lapse occurred between the first public briefing and the next one;
during this time, the people developed a solid wall of resistance. He
felt that continued public information and input by the sponsors would
have alleviated most of the resistance. Governor Hathaway indicated that
El Paso and the AEC were not specific enough regarding the number of
nuclear detonations required for full field development.

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