Nuclear Testing

I

Introduction

Nuclear Testing, nuclear explosions conducted to test nuclear weapons. These may be new designs under development or existing stockpile weapons. The total explosive power of nuclear test explosions carried out to date is estimated to be the equivalent of about 510 million tonnes (510 megatons) of TNT, equivalent to 40,000 times the size of the atomic bomb dropped on Hiroshima in 1945.

A new type of nuclear weapon requires about seven or eight tests before it is put into a country’s nuclear arsenal. In addition, existing stockpile weapons are tested to check that they still work reliably (a warhead is taken at random from the stockpile and exploded), and to improve the safety of nuclear weapons. In these tests, new safety features incorporated in the weapons, such as non-sensitive high explosives, are tested. The sheer numbers, power in terms of megatons, and spectacle of the above-ground tests were essential elements of Cold War competition between the nuclear powers, which to many was considered the true purpose of the tests.

II

Non-Military Nuclear Tests

Nuclear explosions have also been carried out for non-military purposes, for example, for creating underground storage cavities for gas, extracting gas and oil, extinguishing burning oil wells, and building canals. Non-military nuclear explosives are similar to nuclear weapons and military information can be obtained from exploding them. However, objections to “peaceful” nuclear explosions tend to be mainly economic and environmental.

III

Types of Tests

Nuclear tests have been conducted in space, under water, in the atmosphere, on the surface of land, and on water (carried on a raft or contained in a ship, for example). Nuclear weapons exploded in the atmosphere have been dropped as bombs from aircraft, suspended on balloons, exploded on towers, and fired aloft by rockets.

Zero-yield or subcritical tests involve high explosives and fissile material in which the fissile material does not reach a critical mass and therefore does not produce significant fission energy but allows scientists to assess design features and safety. Computer simulation of nuclear explosions has also been carried out by the major nuclear weapons laboratories. Some observers argue that zero-yield tests and computer simulation allow nuclear-weapon powers to improve the performance of their existing nuclear weapons and possibly even develop new types of nuclear weapons.

Others claim that the development of new types of nuclear weapons is not possible without actually testing them. It is also argued that fundamental civilian scientific research will provide nuclear-weapons designers with the knowledge needed to develop an entirely new generation of nuclear weapons.

IV

History of Nuclear Testing

The first nuclear test, code-named Trinity, was conducted by the United States on July 16, 1945, in the desert near Alamogordo, New Mexico. As the culmination of the Manhattan Project, the Trinity test was set up to try out the first plutonium weapon using the implosion method of detonation. The Union of Soviet Socialist Republics (USSR) began testing nuclear weapons in 1949, the United Kingdom followed in 1952; France in 1960; and China in 1964. Each of these four powers conducted nuclear tests in the atmosphere, until 1963, and underground thereafter. The United States, the USSR, France, and the United Kingdom have also conducted tests under water. India officially became a nuclear power when it conducted five underground nuclear tests and a missile test in May 1998, with Pakistan following suit days later with six underground tests. These tests raised fears of a nuclear arms race, or even a conflict, on the subcontinent.

The five officially recognized nuclear powers carried out most of their atmospheric and underground nuclear tests at remote sites, such as in the Nevada desert in the south-western United States; the Marshall Islands and Christmas Islands in the Pacific Ocean; Moruroa and Fangataufa, two atolls in French Polynesia; and Maralinga in Australia.

Out of a total of 2,050 nuclear explosions, about 1,300 have been carried out by the United States. As the Cold War gathered pace, public opposition to atmospheric testing grew, and on August 5, 1963, the United States, the USSR, and the United Kingdom signed a Partial Test Ban Treaty, banning nuclear explosions in the atmosphere, outer space, and under water. France stopped conducting nuclear tests in the atmosphere in 1974; China, in 1980. In 1962 alone, there had been 178 tests; the 500 atmospheric nuclear tests had a total explosive power equivalent to that of about 30,000 Hiroshima bombs. The largest of these—and the most powerful explosion ever—was conducted by the USSR at Novaya Zemlya in 1961; it had an explosive power equivalent to that of 58 megatons, about four times larger than the largest US test.