Nuclear weapons testing is the act of experimentally and deliberately firing one or more nuclear devices in a controlled manner pursuant to a military, scientific or technological goal. This has been done on test sites on land or waters owned, controlled or leased from the owners by one of the eight nuclear nations: the United States, the Soviet Union, the United Kingdom, France, China, India, Pakistan and North Korea, or has been done on or over ocean sites far from territorial waters. There have been 2,121 tests done since the first in July 1945, involving 2,476 nuclear devices. As of 1993, worldwide, 520 atmospheric nuclear explosions (including eight underwater) have been conducted with a total yield of 545 megatons (Mt): 217 Mt from pure fission and 328 Mt from bombs using fusion, while the estimated number of underground nuclear tests conducted in the period from 1957 to 1992 is 1,352 explosions with a total yield of 90 Mt. As a result of the 1996 Comprehensive Nuclear-Test-Ban Treaty, there were no declared tests between the 1998 Pakistani Chagai-II and the 2006 North Korean test, and none outside North Korea to date.
Very few unknown tests are suspected at this time, the Vela incident being the most prominent. Israel is the only country suspected of having nuclear weapons but not confirmed to have ever tested any.
The following are considered nuclear tests:
Single nuclear devices fired in deep horizontal tunnels (drifts) or in vertical shafts, in shallow shafts ("cratering"), underwater, on barges or vessels on the water, on land, in towers, carried by balloons, shot from cannons, dropped from airplanes with or without parachutes, and shot into a ballistic trajectory, into high atmosphere or into near space on rockets. Since 1963 the great majority have been underground due to the Partial Test Ban Treaty. Salvo tests in which several devices are fired simultaneously, as defined by international treaties:
The two nuclear bombs dropped in combat over Japan in 1945. While the primary purpose of these two detonations was military and not experimental, observations were made and the tables would be incomplete without them. Nuclear safety tests in which the nuclear yield was intended to be zero, and which failed to some extent if a nuclear yield was detected. There have been failures, and therefore they are included in the lists, as well as the successes. Fizzles, in which the expected yield was not reached. Tests intended but not completed because of vehicle or other support failures that destroyed the device. Tests that were emplaced and could not be fired for various reasons. Usually, the devices were ultimately destroyed by later conventional or nuclear explosions.
Not included as nuclear tests:
Misfires which were corrected and later fired as intended. Hydro-nuclear or subcritical testing in which the normal fuel material for a nuclear device is below the amount necessary to sustain a chain reaction. The line here is finely drawn, but, among other things, subcritical testing is not prohibited by the Comprehensive Nuclear Test Ban Treaty, while safety tests are.
Tests by country The table in this section summarizes all worldwide nuclear testing (including the two bombs dropped in combat which were not tests). The country names are links to summary articles for each country, which may in turn be used to drill down to test series articles which contain details on every known nuclear explosion and test. The notes attached to various table cells detail how the numbers therein are arrived at.
+ Worldwide nuclear testing totals by countryCountry Tests Devices fired Devices w/ unknown yields Peaceful use tests Non-PTBT tests Yield range (kilotons) Total yield (kilotons) Percentage by tests Percentage by yieldUS Generally regarded as the "official" list of American tests. (Operation Plowshare) 0 to 15,000 USSR (Nuclear Explosions for the National Economy) 0 to 50,000 UK 0 to 3,000 France 0 to 2,600 China 0 to 4,000 India 0 to 60 Pakistan 1 to 45 1 to 250 Total 2,121 2,476 294 188 604 0 to 50,000 540,849
Known tests In the following subsections, a selection of significant tests (by no means exhaustive) is listed, representative of the testing effort in each nuclear country.
United States
The standard official list of tests for American devices is arguably the United States Department of Energy DoE-209 document. The United States conducted around 1,054 nuclear tests (by official count) between 1945 and 1992, including 216 atmospheric, underwater, and space tests. Some significant tests conducted by the United States include:
The Trinity test on 16 July 1945, near Socorro, New Mexico, was the first-ever test of a nuclear weapon (yield of around 20 kilotons). The Operation Crossroads series in July 1946, at Bikini Atoll in the Marshall Islands, was the first postwar test series and one of the largest military operations in U.S. history. The Operation Sandstone test series conducted in April and May 1948 at Eniwetok Atoll in the Marshall Islands, was a critical step in advancing nuclear weapons development. Overseen by Joint Task Force 7 (JTF-7), the operation consisted of three atomic detonations, X-RAY, YOKE, and ZEBRA designed to evaluate new bomb designs with increased efficiency and improved fissile material usage. The Operation Ranger test series was the fourth American nuclear test operation. It was conducted between January 27th and February 6th, 1951 and was the first series to be carried out at the Nevada Test Site. All the bombs were dropped by B-50D bombers and exploded in the open air over Frenchman Flat (Area 5). The Operation Greenhouse shots of May 1951, at Enewetak Atoll in the Marshall Islands, included the first boosted fission weapon test (named Item) and a scientific test (named George) which proved the feasibility of thermonuclear weapons. The Ivy Mike shot of 1 November 1952, at Enewetak Atoll, was the first full test of a Teller-Ulam design staged hydrogen bomb, with a yield of 10 megatons. This was not a deployable weapon. With its full cryogenic equipment it weighed about 82 tons. The Castle Bravo shot of 1 March 1954, at Bikini Atoll, was the first test of a deployable (solid fuel) thermonuclear weapon, and also (accidentally) the largest weapon ever tested by the United States (15 megatons). It was also the single largest U.S. radiological accident in connection with nuclear testing. The unanticipated yield, and a change in the weather, resulted in nuclear fallout spreading eastward onto the inhabited Rongelap and Rongerik atolls, which were soon evacuated. Many of the Marshall Islands natives have since suffered from birth defects and have received some compensation from the federal government of the United States. A Japanese fishing boat, the Daigo Fukuryū Maru, also came into contact with the fallout, which caused many of the crew to grow ill; one eventually died. The crew's exposure was referenced in the film Godzilla as a criticism of American nuclear tests in the Pacific. The Operation Plumbbob series of May–October 1957 is considered the biggest, longest, and most controversial test series that occurred within the continental United States. Rainier Mesa, Frenchman Flat, and Yucca Flat were all used for the 29 different atmospheric explosions. Shot Argus I of Operation Argus, on 27 August 1958, was the first detonation of a nuclear weapon in outer space when a 1.7-kiloton warhead was detonated at 200 kilometers altitude over the South Atlantic Ocean during a series of high-altitude nuclear explosions. Shot Frigate Bird of Operation Dominic on 6 May 1962, was the only U.S. test of an operational ballistic missile with a live nuclear warhead (yield of 600 kilotons), at Johnston Atoll in the Pacific. In general, missile systems were tested without live warheads and warheads were tested separately for safety concerns. In the early 1960s there were mounting questions about how the systems would behave under combat conditions (when they were mated, in military parlance), and this test was meant to dispel these concerns. However, the warhead had to be somewhat modified before its use, and the missile was only a SLBM (and not an ICBM), so by itself, it did not satisfy all concerns. Shot Sedan of Operation Storax on 6 July 1962 (yield of 104 kilotons), was an attempt at showing the feasibility of using nuclear weapons for civilian, peaceful purposes as part of Operation Plowshare. In this instance, a 1280-feet-in-diameter and 320-feet-deep explosion crater, morphologically similar to an impact crater, was created at the Nevada Test Site. Shot Divider of Operation Julin on 23 September 1992, at the Nevada Test Site, was the last U.S. nuclear test. Described as a "test to ensure safety of deterrent forces", the series was interrupted by the beginning of negotiations over the Comprehensive Nuclear-Test-Ban Treaty.
Soviet Union
After the fall of the USSR, the American government (as a member of the International Consortium International Science and Technology Center) hired top scientists in Sarov (aka Arzamas-16, the Soviet equivalent of Los Alamos and thus sometimes called Los Arzamas) to draft documents about the history of the Soviet atomic program. One of the documents was the definitive list of Soviet nuclear tests. Most of the tests have no code names, unlike the American tests, so they are known by their test numbers from this document. Some list compilers have detected discrepancies in that list; one device was abandoned in its cove in a tunnel in Semipalatinsk when the Soviets abandoned Kazakhstan, and one list lists 13 other tests which apparently failed to provide any yield. The source for that was the well respected Russian Strategic Nuclear Forces which confirms 11 of the 13; those 11 are in the Wikipedia lists.
The Soviet Union conducted 715 nuclear tests (by the official count) between 1949 and 1990, including 219 atmospheric, underwater, and space tests. Most of them took place at the Semipalatinsk Test Site in Kazakhstan and the Northern Test Site at Novaya Zemlya. Additional industrial tests were conducted at various locations in Russia and Kazakhstan, while a small number of tests were conducted in Ukraine, Uzbekistan, and Turkmenistan.
In addition, the large-scale military exercise was conducted by Soviet army to explore the possibility of defensive and offensive warfare operations on the nuclear battlefield. The exercise, under code name of Snezhok (Snowball), involved detonation of a nuclear bomb twice as powerful as the one used in Nagasaki and approximately 45,000 soldiers coming through the epicenter immediately after the blastViktor Suvorov, Shadow of Victory (), Donetsk, 2003, , pages 353–375. The exercise was conducted on September 14, 1954, under command of Marshal Georgy Zhukov to the north of Totskoye village in Orenburg Oblast, Russia.
Some significant Soviet tests include: Operation First Lightning/RDS-1 (known as Joe 1 in the West), August 29, 1949: first Soviet nuclear test. RDS-6s (known as Joe 4 in the West), August 12, 1953: first Soviet thermonuclear test using a sloyka (layer cake) design. The design proved to be unscalable into megaton yields, but it was air-deployable. RDS-37, November 22, 1955: first Soviet multi-megaton, true hydrogen bomb test using Andrei Sakharov's third idea, essentially a re-invention of the Teller-Ulam. Tsar Bomba, October 30, 1961: largest nuclear weapon ever detonated, with a design yield of 100 Mt, de-rated to 50 Mt for the test drop. Chagan, January 15, 1965: large cratering experiment as part of Nuclear Explosions for the National Economy program, which created an artificial lake.