Thermonuclear warhead | Nuclear Weapon Design & Delivery (2024)

weapon

verifiedCite

While every effort has been made to follow citation style rules, there may be some discrepancies.Please refer to the appropriate style manual or other sources if you have any questions.

Select Citation Style

Feedback

Thank you for your feedback

Our editors will review what you’ve submitted and determine whether to revise the article.

printPrint

Please select which sections you would like to print:

verifiedCite

While every effort has been made to follow citation style rules, there may be some discrepancies.Please refer to the appropriate style manual or other sources if you have any questions.

Select Citation Style

Feedback

Thank you for your feedback

Our editors will review what you’ve submitted and determine whether to revise the article.

Also known as: nuclear warhead

Written by

Robert S. Norris Dr. Norris was a senior research associate with the Natural Resources Defense Council in Washington, DC from 1984 to his retirement in 2011. His principal areas of expertise include writing and research...

Robert S. Norris,

Thomas B. Cochran Dr. Thomas B. Cochran is a consultant to the Natural Resources Defense Council where he began working in 1973. Prior to retiring in 2011, he was a senior scientist and held the Wade Greene Chair for Nuclear...

Thomas B. CochranAll

Fact-checked by

The Editors of Encyclopaedia Britannica Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. They write new content and verify and edit content received from contributors.

The Editors of Encyclopaedia Britannica

Last Updated: Article History

Teller-Ulam bomb design

See all media

Also known as:
nuclear warhead
Related Topics:
thermonuclear bomb

See all related content →

thermonuclear warhead, thermonuclear (fusion) bomb designed to fit inside a missile. By the early 1950s both the United States and the Soviet Union had developed nuclear warheads that were small and light enough for missile deployment, and by the late 1950s both countries had developed intercontinental ballistic missiles (ICBMs) capable of delivering thermonuclear warheads around the world.

Basic two-stage design

A typical thermonuclear warhead may be constructed according to a two-stage design, featuring a fission or boosted-fission primary (also called the trigger) and a physically separate component called the secondary. Both primary and secondary are contained within an outer metal case. Radiation from the fission explosion of the primary is contained and used to transfer energy to compress and ignite the secondary. Some of the initial radiation from the primary explosion is absorbed by the inner surface of the case, which is made of a high-density material such as uranium. Radiation absorption heats the inner surface of the case, turning it into an opaque boundary of hot electrons and ions. Subsequent radiation from the primary is largely confined between this boundary and the outer surface of the secondary capsule. Initial, reflected, and re-irradiated radiation trapped within this cavity is absorbed by lower-density material within the cavity, converting it into a hot plasma of electrons and ion particles that continue to absorb energy from the confined radiation. The total pressure in the cavity—the sum of the contribution from the very energetic particles and the generally smaller contribution from the radiation—is applied to the secondary capsule’s heavy metal outer shell (called a pusher), thereby compressing the secondary.

Typically, contained within the pusher is some fusion material, such as lithium-6 deuteride, surrounding a “spark plug” of explosive fissionable material (generally uranium-235) at the centre. With the fission primary generating an explosive yield in the kiloton range, compression of the secondary is much greater than can be achieved using chemical high explosives. Compression of the spark plug results in a fission explosion that creates temperatures comparable to those of the Sun and a copious supply of neutrons for fusion of the surrounding, and now compressed, thermonuclear materials. Thus, the fission and fusion processes that take place in the secondary are generally much more efficient than those that take place in the primary.

In an efficient, modern two-stage device—such as a long-range ballistic missile warhead—the primary is boosted in order to conserve on volume and weight. Boosted primaries in modern thermonuclear weapons contain about 3 to 4 kg (6.6 to 8.8 pounds) of plutonium, while less-sophisticated designs may use double that amount or more. The secondary typically contains a composite of fusion and fissile materials carefully tailored to maximize the yield-to-weight or yield-to-volume ratio of the warhead, although it is possible to construct secondaries from purely fissile or fusion materials.

Enhanced designs

Historically, some very high-yield thermonuclear weapons had a third, or tertiary, stage. In theory, the radiation from the tertiary can be contained and used to transfer energy to compress and ignite a fourth stage, and so on. There is no theoretical limit to the number of stages that might be used and, consequently, no theoretical limit to the size and yield of a thermonuclear weapon. However, there is a practical limit because of size and weight limitations imposed by the requirement that the weapon be deliverable.

Uranium-238 and thorium-232 (and some other fissionable materials) cannot maintain a self-sustaining fission explosion, but these isotopes can be made to fission by an externally maintained supply of fast neutrons from fission or fusion reactions. Thus, the yield of a nuclear weapon can be increased by surrounding the device with uranium-238, in the form of either natural or depleted uranium, or with thorium-232, in the form of natural thorium. This approach is particularly advantageous in a thermonuclear weapon in which uranium-238 or thorium-232 in the outer shell of the secondary capsule is used to absorb an abundance of fast neutrons from fusion reactions produced within the secondary. The explosive yields of some weapon designs have been further increased by the substitution of highly enriched uranium-235 for uranium-238 in the secondary.

Are you a student? Get a special academic rate on Britannica Premium.

Learn More

In general, the energy released in the explosion of a high-yield thermonuclear weapon stems from the boosted-fission chain reaction in the primary stage and the fissioning and “burning” of thermonuclear fuel in the secondary (and any subsequent) stage, with roughly 50 to 75 percent of the total energy produced by fission and the remainder by fusion. However, to obtain tailored weapon effects or to meet certain weight or space constraints, different ratios of fission yield to fusion yield may be employed, ranging from nearly pure fission weapons to a weapon where a very high proportion of the yield is from fusion.

Another tailored weapon is the enhanced radiation warhead, or neutron bomb, a low-yield (on the order of one kiloton), two-stage thermonuclear device designed to intensify the production of lethal fast neutrons in order to maximize mortality rates while producing less damage to buildings. The enhanced radiation is in the form of fast neutrons produced by the fusion of deuterium and tritium. The secondary contains little or no fissionable material, since this would increase the blast effect without significantly increasing the intensity of fast neutrons. The United States produced enhanced-radiation warheads for antiballistic missiles, short-range ballistic missiles, and artillery shells.

Robert S. NorrisThomas B. Cochran
Thermonuclear warhead | Nuclear Weapon Design & Delivery (2024)

FAQs

What is the design of thermonuclear weapons? ›

Basic two-stage design

A typical thermonuclear warhead may be constructed according to a two-stage design, featuring a fission or boosted-fission primary (also called the trigger) and a physically separate component called the secondary. Both primary and secondary are contained within an outer metal case.

What is the most powerful thermonuclear weapon? ›

Tsar Bomba, Soviet thermonuclear bomb that was detonated in a test over Novaya Zemlya island in the Arctic Ocean on October 30, 1961. The largest nuclear weapon ever set off, it produced the most powerful human-made explosion ever recorded.

What is the secret code for nuclear weapons? ›

The Gold Code is the launch code for nuclear weapons provided to the President of the United States in their role as commander-in-chief of the armed forces. In conjunction with the nuclear football, the Gold Codes allow the president to authorize a nuclear attack.

Has a thermonuclear bomb ever been dropped? ›

On 28 April 1958 a bomb was dropped that yielded 3 Mt (13 PJ)—Britain's most powerful test. Two final air burst tests on 2 and 11 September 1958, dropped smaller bombs that yielded around 1 Mt (4.2 PJ) each.

Is it illegal to make a thermonuclear bomb? ›

Treaty Obligations. The Treaty on the Prohibition of Nuclear Weapons (TPNW) prohibits States Parties from developing, testing, producing, manufacturing, acquiring, possessing, or stockpiling nuclear weapons or other nuclear explosive devices.

What is stronger thermonuclear or nuclear? ›

Which is more powerful, a thermonuclear bomb or an atomic bomb? Thermonuclear bombs can be hundreds or even thousands of times more powerful than atomic bombs.

How many Tsar bombs would it take to destroy the world? ›

The Tsar Bomba was certainly not a practical weapon; even so, it would take 10 million Tsar Bombas detonated at the centre of the earth to ensure destruction of the planet. It may not be possible for nuclear weapons to destroy the earth, but destroying humanity is possible.

How many states can a nuke destroy? ›

Theoretically there is no real limit to the yield of a thermonuclear bomb. Also, the Tsar bomba which was detonated in 1961, could have easily wiped out Rhode Island, Delaware or most of Maryland so, yes, you could potentially destroy an entire state with one thermonuclear bomb.

What is the deadliest bomb in the world? ›

The Tsar Bomba (Russian: Царь-бомба, romanized: Tsar'-bomba, IPA: [t͡sarʲ ˈbombə], lit. 'Tsar bomb'; code name: Ivan or Vanya), also known by the alphanumerical designation "AN602", was a thermonuclear aerial bomb, and the most powerful nuclear weapon ever created and tested.

What is the old US nuclear code? ›

In a nutshell, my claim was, and is, that prior to 1977 a panel inside Minuteman underground launch control centers used to electronically 'unlock' their silo-based strategic missiles had to be set to eight zeroes – 00000000 – prior to the crews turning keys to fire them.

Can the president launch nukes without permission? ›

Many sources show that the president has sole launch authority, and the defense secretary has no veto power. However, it has been argued that the president may not have sole authority to initiate a nuclear attack because the defense secretary is required to verify the order but cannot veto it.

Who gave Israel nuclear weapons? ›

The French justified their decision to provide Israel a nuclear reactor by claiming it was not without precedent. In September 1955 Canada publicly announced that it would help the Indian government build a heavy-water research reactor, the CIRUS reactor, for "peaceful purposes".

How many US nukes are missing? ›

Additionally, the declassified 1966 report discussed another lost nuclear weapon incident from 1965 in the western Pacific in which a plane had gone over the side of an aircraft carrier in 2,700 fathoms. The aircraft, pilot, and weapon were never found. The United States is reportedly missing six nuclear bombs to date.

Is there a nuclear bomb that can wipe out the whole world? ›

No. In practice, nuclear weapons have gotten smaller. Bombs like the 50MT Tsar Bomba simply have no military value, and anyway, there are practical limits to how large a weapon can be because after all, it destroys itself during operation.

What are the principles of thermonuclear weapons? ›

Thermonuclear weapons, sometimes referred to as Hydrogen, or “H-bombs,” utilize both atomic fission and nuclear fusion to create an explosion. The combination of these two processes releases massive amounts of energy, hundreds to thousands of times more powerful than an atomic bomb.

What is the difference between a bomb and a thermonuclear bomb? ›

A thermonuclear bomb differs fundamentally from an atomic bomb in that it utilizes the energy released when two light atomic nuclei combine, or fuse, to form a heavier nucleus. An atomic bomb, by contrast, uses the energy released when a heavy atomic nucleus splits, or fissions, into two lighter nuclei.

What was the top secret project to design nuclear weapons called? ›

The Manhattan Project was an unprecedented, top-secret World War II government program in which the United States rushed to develop and deploy the world's first atomic weapons before Nazi Germany.

What is the radius of a thermonuclear weapon? ›

The heat from a 1 KT detonation could cause 50% mortality, from thermal burns, to individuals within an approximate 0.4 miles (610 m) radius. This radius increases to approximately 1.1 miles (1800 m) for a 10 KT detonation.

Top Articles
Latest Posts
Recommended Articles
Article information

Author: Rubie Ullrich

Last Updated:

Views: 6049

Rating: 4.1 / 5 (52 voted)

Reviews: 91% of readers found this page helpful

Author information

Name: Rubie Ullrich

Birthday: 1998-02-02

Address: 743 Stoltenberg Center, Genovevaville, NJ 59925-3119

Phone: +2202978377583

Job: Administration Engineer

Hobby: Surfing, Sailing, Listening to music, Web surfing, Kitesurfing, Geocaching, Backpacking

Introduction: My name is Rubie Ullrich, I am a enthusiastic, perfect, tender, vivacious, talented, famous, delightful person who loves writing and wants to share my knowledge and understanding with you.