![NTS test preparation4](https://upload.wikimedia.org/wikipedia/commons/c/cc/NTS_test_preparation4.jpg)
Underground nuclear testing is the
test detonation of
nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions ( thermonuclear bomb), producing a nuclear explosion. Both bom ...
s that is performed underground. When the device being tested is buried at sufficient depth, the
nuclear explosion
A nuclear explosion is an explosion that occurs as a result of the rapid release of energy from a high-speed nuclear reaction. The driving reaction may be nuclear fission or nuclear fusion or a multi-stage cascading combination of the two, t ...
may be contained, with no release of
radioactive material
A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transfer ...
s to the atmosphere.
The extreme heat and pressure of an underground nuclear explosion causes changes in the surrounding rock. The rock closest to the location of the test is
vaporised
Vaporization (or vaporisation) of an element or compound is a phase transition from the liquid phase to vapor. There are two types of vaporization: evaporation and boiling. Evaporation is a surface phenomenon, whereas boiling is a bulk phenomenon. ...
, forming a cavity. Farther away, there are zones of crushed, cracked, and irreversibly strained rock. Following the explosion, the rock above the cavity may collapse, forming a rubble chimney. If this chimney reaches the surface, a bowl-shaped
subsidence crater
__NOTOC__
A subsidence crater is a hole or depression left on the surface of an area which has had an underground (usually nuclear) explosion. Many such craters are commonly present at bomb testing areas; one notable example is the Nevada Test S ...
may form.
The first underground test took place in 1951; further tests provided information that eventually led to the signing of the
Limited Test Ban Treaty
The Partial Test Ban Treaty (PTBT) is the abbreviated name of the 1963 Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space and Under Water, which prohibited all test detonations of nuclear weapons except for those conducted ...
in 1963, which banned all nuclear tests except for those performed underground. From then until the signing of the
Comprehensive Nuclear-Test-Ban Treaty
The Comprehensive Nuclear-Test-Ban Treaty (CTBT) is a multilateral treaty to ban nuclear weapons test explosions and any other nuclear explosions, for both civilian and military purposes, in all environments. It was adopted by the United Nations ...
in 1996, most nuclear tests were performed underground, in order to prevent
nuclear fallout
Nuclear fallout is the residual radioactive material propelled into the upper atmosphere following a nuclear blast, so called because it "falls out" of the sky after the explosion and the shock wave has passed. It commonly refers to the radioac ...
from entering into the atmosphere.
Background
Although public concern about fallout from nuclear testing grew in the early 1950s,
fallout was discovered after the ''
Trinity
The Christian doctrine of the Trinity (, from 'threefold') is the central dogma concerning the nature of God in most Christian churches, which defines one God existing in three coequal, coeternal, consubstantial divine persons: God the F ...
'' test, the first ever atomic bomb test, in 1945.
Photographic film manufacturers later reported
'fogged' films; this was traced to packaging materials sourced from Indiana crops, contaminated by ''Trinity'' and later tests at the
Nevada Test Site
The Nevada National Security Site (N2S2 or NNSS), known as the Nevada Test Site (NTS) until 2010, is a United States Department of Energy (DOE) reservation located in southeastern Nye County, Nevada, about 65 miles (105 km) northwest of th ...
, over 1,000 miles (≈1600 kilometres) away.
Intense fallout from the 1953 ''
Simon
Simon may refer to:
People
* Simon (given name), including a list of people and fictional characters with the given name Simon
* Simon (surname), including a list of people with the surname Simon
* Eugène Simon, French naturalist and the genus ...
'' test was documented as far as Albany, New York.
The fallout from the March 1954 ''
Bravo
Bravo(s) or The Bravo(s) may refer to:
Arts and entertainment Music Groups and labels
*Bravo (band), a Russian rock band
* Bravo (Spanish group), represented Spain at Eurovision 1984
*Bravo Music, an American concert band music publishing company ...
'' test in the
Pacific Ocean
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
had "scientific, political and social implications that have continued for more than 40 years".
The multi-
megaton
Megaton may refer to:
* A million tons
* Megaton TNT equivalent, explosive energy equal to 4.184 petajoules
* megatonne, a million tonnes, SI unit of mass
Other uses
* Olivier Megaton (born 1965), French film director, writer and editor
* ''Me ...
test caused fallout to occur on the islands of the
Rongerik
Rongerik Atoll or Rongdrik Atoll ( Marshallese: , ) is a coral atoll of 17 islands in the Pacific Ocean, and is located in the Ralik Chain of the Marshall Islands, approximately east of Bikini Atoll. Its total land area is only , but it encloses ...
and
Rongelap
Rongelap Atoll ( Marshallese: , ) is a coral atoll of 61 islands (or motus) in the Pacific Ocean, and forms a legislative district of the Ralik Chain of the Marshall Islands. Its total land area is . It encloses a lagoon with an area of . ...
atolls, and a
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
ese fishing boat known as the ''
Daigo Fukuryū Maru
was a Japanese tuna fishing boat with a crew of 23 men which was contaminated by nuclear fallout from the United States Castle Bravo thermonuclear weapon test at Bikini Atoll on March 1, 1954.
The crew suffered acute radiation syndrome (ARS) ...
'' (Lucky Dragon).
Prior to this test, there was "insufficient" appreciation of the dangers of fallout.
The test became an international incident. In a
Public Broadcasting Service
The Public Broadcasting Service (PBS) is an American public broadcaster and non-commercial, free-to-air television network based in Arlington, Virginia. PBS is a publicly funded nonprofit organization and the most prominent provider of educati ...
(PBS) interview, the historian Martha Smith argued: "In Japan, it becomes a huge issue in terms of not just the government and its protest against the United States, but all different groups and all different peoples in Japan start to protest. It becomes a big issue in the media. There are all kinds of letters and protests that come from, not surprisingly, Japanese fishermen, the fishermen's wives; there are student groups, all different types of people; that protest against the Americans' use of the Pacific for nuclear testing. They're very concerned about, first of all, why the United States even has the right to be carrying out those kinds of tests in the Pacific. They're also concerned about the health and environmental impact." The Prime Minister of India "voiced the heightened international concern" when he called for the elimination of all nuclear testing worldwide.
Knowledge about
fallout and its effects grew, and with it
concern about the global environment and long-term
genetic damage
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mitos ...
.
Talks between the United States, the United Kingdom, Canada, France, and the Soviet Union began in May 1955 on the subject of an international agreement to end nuclear tests.
On August 5, 1963, representatives of the
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
, the
Soviet Union
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national ...
, and the
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...
signed the Limited Test Ban Treaty, forbidding testing of nuclear weapons in the atmosphere, in space, and underwater.
Agreement was facilitated by the decision to allow underground testing, eliminating the need for on-site inspections that concerned the Soviets.
Underground testing was allowed, provided that it does not cause "radioactive debris to be present outside the territorial limits of the State under whose jurisdiction or control such explosion is conducted".
Early history of underground testing
Following analysis of underwater detonations that were part of ''
Operation Crossroads
Operation Crossroads was a pair of nuclear weapon tests conducted by the United States at Bikini Atoll in mid-1946. They were the first nuclear weapon tests since Trinity in July 1945, and the first detonations of nuclear devices since the ...
'' in 1946, inquiries were made regarding the possible military value of an underground explosion.
The US
Joint Chiefs of Staff
The Joint Chiefs of Staff (JCS) is the body of the most senior uniformed leaders within the United States Department of Defense, that advises the president of the United States, the secretary of defense, the Homeland Security Council and the ...
thus obtained the agreement of the
United States Atomic Energy Commission
The United States Atomic Energy Commission (AEC) was an agency of the United States government established after World War II by U.S. Congress to foster and control the peacetime development of atomic science and technology. President H ...
(AEC) to perform experiments on both surface and sub-surface detonations.
The Alaskan island of
Amchitka
Amchitka (; ale, Amchixtax̂; russian: Амчитка) is a volcanic, tectonically unstable and uninhabited
island in the Rat Islands group of the Aleutian Islands in southwest Alaska. It is part of the Alaska Maritime National Wildlife Refu ...
was initially selected for these tests in 1950, but the site was later deemed unsuitable and the tests were moved to the Nevada Test Site.
![UncleNuclearTest1951](https://upload.wikimedia.org/wikipedia/commons/4/44/UncleNuclearTest1951.jpg)
The first underground nuclear test was conducted on 29 November 1951.
This was the 1.2
kiloton
TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion. The is a unit of energy defined by that convention to be , which is the approximate energy released in the detonation of a t ...
''
Buster-Jangle Uncle'', which detonated 5.2 m (17 ft) beneath ground level.
The test was designed as a scaled-down investigation of the effects of a 23-kiloton ground-penetrating
gun-type fission weapon
Gun-type fission weapons are fission-based nuclear weapons whose design assembles their fissile material into a supercritical mass by the use of the "gun" method: shooting one piece of sub-critical material into another. Although this is sometim ...
that was then being considered for use as a cratering and
bunker-buster weapon.
The explosion resulted in a cloud that rose to 3,500 m (11,500 ft), and deposited fallout to the north and north-northeast.
The resulting crater was 79 m (260 ft) wide and 16 m (53 ft) deep.
![Operation Teapot - Ess](https://upload.wikimedia.org/wikipedia/commons/0/04/Operation_Teapot_-_Ess.jpg)
The next underground test was ''Teapot Ess'', on 23 March 1955.
The one-kiloton explosion was an operational test of an '
Atomic Demolition Munition
Atomic demolition munitions (ADMs), colloquially known as nuclear land mines, are small nuclear explosive devices. ADMs were developed for both military and civilian purposes. As weapons, they were designed to be exploded in the forward battle a ...
' (ADM).
It was detonated 20.4 m (67 ft) underground, in a shaft lined with corrugated steel, which was then back-filled with sandbags and dirt.
Because the ADM was buried underground, the explosion blew tons of earth upwards,
creating a crater 91 m (300 ft) wide and 39 m (128 ft) deep.
The resulting
mushroom cloud
A mushroom cloud is a distinctive mushroom-shaped flammagenitus cloud of debris, smoke and usually condensed water vapor resulting from a large explosion. The effect is most commonly associated with a nuclear explosion, but any sufficiently ener ...
rose to a height of and subsequent
radioactive fallout
Nuclear fallout is the residual radioactive material propelled into the upper atmosphere following a nuclear blast, so called because it "falls out" of the sky after the explosion and the shock wave has passed. It commonly refers to the radioac ...
drifted in an easterly direction, travelling as far as from ground zero.
On 26 July 1957, ''
Plumbbob Pascal-A'' was detonated at the bottom of a shaft.
According to one description, it "ushered in the era of underground testing with a magnificent pyrotechnic
roman candle!"
As compared with an above-ground test, the radioactive debris released to the atmosphere was reduced by a factor of ten.
Theoretical work began on possible containment schemes.
![Plumbbob Rainier 011](https://upload.wikimedia.org/wikipedia/commons/c/c5/Plumbbob_Rainier_011.jpg)
''Plumbbob Rainier'' was detonated at underground on 19 September 1957.
The 1.7 kt explosion was the first to be entirely contained underground, producing no fallout.
The test took place in a 1,600 – 2,000 ft
(488 – 610 m) horizontal tunnel in the shape of a hook.
The hook "was designed so explosive force will seal off the non-curved portion of tunnel nearest the detonation before gases and fission fragments can be vented around the curve of the tunnel's hook".
This test would become the prototype for larger, more powerful tests.
Rainier was announced in advance, so that seismic stations could attempt to record a signal.
Analysis of samples collected after the test enabled scientists to develop an understanding of underground explosions that "persists essentially unaltered today".
The information would later provide a basis for subsequent decisions to agree to the Limited Test Ban Treaty.
''
Cannikin'', the last test at the facility on Amchitka, was detonated on 6 November 1971. At approximately 5
megatons
TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion. The is a unit of energy defined by that convention to be , which is the approximate energy released in the detonation of a m ...
, it was the largest underground test in US history.
Effects
![Nuclear explosion craters schema 1](https://upload.wikimedia.org/wikipedia/commons/6/6f/Nuclear_explosion_craters_schema_1.png)
The effects of an underground nuclear test may vary according to factors including the depth and
yield of the explosion, as well as the nature of the surrounding rock.
If the test is conducted at sufficient depth, the test is said to be ''contained'', with no venting of gases or other contaminants to the environment.
In contrast, if the device is buried at insufficient depth ("underburied"), then rock may be expelled by the explosion, forming a subsidence crater surrounded by
ejecta
Ejecta (from the Latin: "things thrown out", singular ejectum) are particles ejected from an area. In volcanology, in particular, the term refers to particles including pyroclastic materials (tephra) that came out of a volcanic explosion and magma ...
, and releasing high-pressure gases to the atmosphere (the resulting crater is usually conical in profile, circular, and may range between tens to hundreds of metres in diameter and depth
). One figure used in determining how deeply the device should be buried is the ''scaled depth of burial'', or ''-burst'' (SDOB)
This figure is calculated as the burial depth in metres divided by the
cube root
In mathematics, a cube root of a number is a number such that . All nonzero real numbers, have exactly one real cube root and a pair of complex conjugate cube roots, and all nonzero complex numbers have three distinct complex cube roots. Fo ...
of the yield in kilotons. It is estimated that, in order to ensure containment, this figure should be greater than 100.
The energy of the nuclear explosion is released in one
microsecond
A microsecond is a unit of time in the International System of Units (SI) equal to one millionth (0.000001 or 10−6 or ) of a second. Its symbol is μs, sometimes simplified to us when Unicode is not available.
A microsecond is equal to 1000 n ...
. In the following few microseconds, the test hardware and surrounding rock are vaporised, with temperatures of several million degrees and pressures of several million
atmospheres
The standard atmosphere (symbol: atm) is a unit of pressure defined as Pa. It is sometimes used as a ''reference pressure'' or ''standard pressure''. It is approximately equal to Earth's average atmospheric pressure at sea level.
History
The s ...
.
Within
millisecond
A millisecond (from '' milli-'' and second; symbol: ms) is a unit of time in the International System of Units (SI) equal to one thousandth (0.001 or 10−3 or 1/1000) of a second and to 1000 microseconds.
A unit of 10 milliseconds may be called ...
s, a bubble of high-pressure gas and steam is formed. The heat and expanding shock wave cause the surrounding rock to vaporise, or be melted further away, creating a ''melt cavity''.
The shock-induced motion and high internal pressure cause this cavity to expand outwards, which continues over several tenths of a second until the pressure has fallen sufficiently, to a level roughly comparable with the weight of the rock above, and can no longer grow.
Although not observed in every explosion, four distinct zones (including the melt cavity) have been described in the surrounding rock. The ''crushed zone'', about two times the radius of the cavity, consists of rock that has lost all of its former integrity. The ''cracked zone'', about three times the cavity radius, consists of rock with radial and concentric fissures. Finally, the ''zone of irreversible strain'' consists of rock deformed by the pressure.
The following layer undergoes only an
elastic deformation
In engineering, deformation refers to the change in size or shape of an object. ''Displacements'' are the ''absolute'' change in position of a point on the object. Deflection is the relative change in external displacements on an object. Strain ...
; the strain and subsequent release then forms a
seismic wave
A seismic wave is a wave of acoustic energy that travels through the Earth. It can result from an earthquake, volcanic eruption, magma movement, a large landslide, and a large man-made explosion that produces low-frequency acoustic energy. S ...
. A few seconds later the molten rock starts collecting on the bottom of the cavity and the cavity content begins cooling. The rebound after the shock wave causes compressive forces to build up around the cavity, called a stress containment cage, sealing the cracks.
[The Containment of Underground Nuclear Explosions](_blank)
(PDF) . Retrieved on 2010-02-08.
![Huron King Crater 2](https://upload.wikimedia.org/wikipedia/commons/f/f6/Huron_King_Crater_2.jpg)
Several minutes to days later, once the heat dissipates enough, the steam condenses, and the pressure in the cavity falls below the level needed to support the overburden, the rock above the void falls into the cavity. Depending on various factors, including the yield and characteristics of the burial, this collapse may extend to the surface. If it does, a
subsidence crater
__NOTOC__
A subsidence crater is a hole or depression left on the surface of an area which has had an underground (usually nuclear) explosion. Many such craters are commonly present at bomb testing areas; one notable example is the Nevada Test S ...
is created.
Such a crater is usually bowl-shaped, and ranges in size from a few tens of metres to over a kilometre in diameter.
At the
Nevada Test Site
The Nevada National Security Site (N2S2 or NNSS), known as the Nevada Test Site (NTS) until 2010, is a United States Department of Energy (DOE) reservation located in southeastern Nye County, Nevada, about 65 miles (105 km) northwest of th ...
, 95 percent of tests conducted at a scaled depth of burial (SDOB) of less than 150 caused surface collapse, compared with about half of tests conducted at a SDOB of less than 180.
The radius ''r'' (in feet) of the cavity is proportional to the
cube root
In mathematics, a cube root of a number is a number such that . All nonzero real numbers, have exactly one real cube root and a pair of complex conjugate cube roots, and all nonzero complex numbers have three distinct complex cube roots. Fo ...
of the yield ''y'' (in kilotons), ''r'' = 55 *