The W88 is an American thermonuclear warhead , with an estimated yield of 475 kilotons of TNT (1,990 TJ), and is small enough to fit on MIRVed missiles. The W88 was designed at the Los Alamos National Laboratory in the 1970s. In 1999, the director of Los Alamos who had presided over its design described it as "the most advanced U.S. nuclear warhead". As of 2021, the latest version is called the W88 ALT 370, the first unit of which came into production on 1 July, 2021, after 11 years of development. The Trident II submarine-launched ballistic missile (SLBM) can be armed with up to eight W88 warheads (Mark 5 re-entry vehicle) or twelve 100 kt W76 warheads (Mark 4 re-entry vehicle), but it is limited to eight warheads under the Strategic Offensive Reductions Treaty .
17-722: Much of the work was done on the warhead by Los Alamos National Laboratory before the introduction of the Threshold Test Ban Treaty in 1976. A production run of 4000 to 5000 warheads was initially envisioned but production was halted after the November 1989 raid on the Rocky Flats Plant by the FBI. Consideration was given to restarting production but the program was terminated in January 1992. Final production
34-409: A certain number of tests for calibration purposes. By establishing the correlation between stated yields of explosions at the specified sites and the seismic signals produced, this exchange improved assessments by both parties of the yields of nuclear explosions based primarily on the measurements derived from their seismic instruments. The tests used for calibration purposes may be tests conducted in
51-418: A protocol which detailed technical data to be exchanged and which limited weapon testing to specific designated test sites to assist verification. The data to be exchanged included information on the geographical boundaries and geology of the testing areas. Geological data—including such factors as density of rock formation, water saturation, and depth of the water table—are useful in verifying test yields because
68-532: A yield exceeding 150 kilotons after March 31, 1976. The threshold is militarily important since it removes the possibility of testing new or existing nuclear weapons going beyond the fractional-megaton range. In the 1960s, many tests above 150 kilotons were conducted by both countries. The mutual restraint imposed by the Treaty reduced the explosive force of new nuclear warheads and bombs which could otherwise be tested for weapons systems. Of particular significance
85-654: Is one-dimensional, while an axially symmetric simulation is two dimensional. Simulations typically divide up each dimension into discrete segments, so a one-dimensional simulation might involve only 100 points, while a similarly accurate two dimensional simulation would require 10,000. This would likely be the reason they would be desirable for a country like the People's Republic of China, which already developed its own nuclear and thermonuclear weapons, especially since they were no longer conducting nuclear testing which would provide valuable design information. The weapon contains
102-609: The primary, secondary, and casing. In 1999, the San Jose Mercury News reported that the W88 had an egg-shaped primary and a spherical secondary , which were together inside a radiation case known as the "peanut" for its shape. Four months later, The New York Times reported that in 1995 a supposed double agent from the People's Republic of China delivered information indicating that China knew these details about
119-533: The Treaty to the Senate for advice and consent to ratification. The entire understanding is as follows: Both Parties will make every effort to comply fully with all the provisions of the TTB Treaty. However, there are technical uncertainties associated with predicting the precise yields of nuclear weapons tests . These uncertainties may result in slight, unintended breaches of the 150 kiloton threshold. Therefore,
136-461: The W88 warhead as well, supposedly through espionage (this line of investigation eventually resulted in the abortive trial of Wen Ho Lee ). If these stories are true, it would indicate a variation of the Teller-Ulam design which would allow for the miniaturization required for small MIRVed warheads. The value of an egg-shaped primary lies apparently in the fact that a MIRV warhead is limited by
153-482: The diameter of the primary—if an egg-shaped primary can be made to work properly, then the MIRV warhead can be made considerably smaller yet still deliver a high-yield explosion—a W88 warhead manages to yield up to 475 kt with a reentry vehicle length of approximately 60 inches (1,500 mm) and base diameter of 18 inches (460 mm) while the actual physics package is 35 inches (890 mm) long. By different estimates
170-637: The material Fogbank . While its precise nature is classified, Fogbank is believed to be a foam or aerogel material used in the weapon's interstage. Threshold Test Ban Treaty The Treaty on the Limitation of Underground Nuclear Weapon Tests , also known as the Threshold Test Ban Treaty ( TTBT ), was signed in July 1974 by the United States and Soviet Union . It establishes a nuclear "threshold" by prohibiting nuclear tests of devices having
187-407: The past or new tests. Agreement to exchange the detailed data described above represented a significant degree of direct cooperation by the two major nuclear powers in the effort to control nuclear weapons. For the first time, each party agreed to make available to the other data relating to its nuclear weapons test program. The technical problems associated with a yield threshold were recognized by
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#1732776141169204-400: The seismic signal produced by a given underground nuclear explosion varies with these factors at the test location. After an actual test has taken place, the geographic coordinates of the test location are to be furnished to the other party, to help in placing the test in the proper geological setting and thus in assessing the yield. The treaty also stipulates that data will be exchanged on
221-492: The sides in the spring of 1974. In this context the Soviet Union mentioned the idea of some misunderstandings concerning occasional, minor, unintended breaches. Discussions on the subject of such an understanding took place in the autumn of 1974 and in the spring of 1976. The Soviet Union was informed by the United States that the understanding reached would be included as part of the public record associated with submitting
238-449: The two sides have discussed this problem and agreed that: (1) one or two slight, unintended breaches per year would not be considered a violation of the Treaty; (2) such breaches would be a cause for concern, however, and, at the request of either Party, would be the subject for consultations. Warhead A warhead is the section of a device that contains the explosive agent or toxic (biological, chemical, or nuclear) material that
255-420: The warhead has been given weights of 175 kilograms (386 lb), 180 kilograms (400 lb), and 360 kilograms (790 lb). The smaller warhead allows more of them to fit onto a single missile and improves basic flight properties such as speed and range. The calculations for a nonspherical primary are apparently orders of magnitude more difficult than for a spherical primary. A spherically symmetric simulation
272-454: Was approximately 400 warheads. Information about the W88 has implied that it is a variation of the standard Teller–Ulam design for thermonuclear weapons . In a thermonuclear weapon such as the W88, nuclear fission in the primary stage causes nuclear fusion in the secondary stage, which results in the main explosion. Although the weapon employs fusion in the secondary , most of the explosive yield comes from fission of nuclear material in
289-657: Was the relationship between explosive power of reliable, tested warheads and first-strike capability. Agreement on the Threshold Test Ban Treaty was reached during the summit meeting in Moscow in July 1974. Ratification did not occur until 1990 for a number of reasons, including agreeing on ways to verify compliance. To address this issue, both countries agreed to the Joint Verification Experiment in 1988. The treaty included
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