Thermo comes from the Greek word thérmé, which means heat.
Nucleus comes from the Latin word for nut (nux) or kernel, which refers to the very centre of a physical structure.
Sometimes known as Hydrogen bombs or H-Bombs, although this is a slight misnomer as the majority of the explosive power comes from the fission of uranium atoms, and not hydrogen. Although pure hydrogen can be an important part of the overall fusion reaction, if used instead of deuterium or tritium (both of which are isotopes of hydrogen, however).
Thermonuclear bombs and missiles are the most devastating weapons of war that humankind has ever known. The vast majority of all nuclear weapons on this planet are of the Teller-Ulam design. Meaning they are multi-stage, multi-megaton, fusion-based devices.
These weapons are named as such due to the fact they utilize the intense x-ray radiation and subsequent heat of a fission reaction (the type of reaction used purely in the bombs dropped on Japan in 1945) to then initiate the hugely powerful fusion reaction thereafter. No thermonuclear weapons have ever been used in anger against any country thus far, and it's probably best for all of humanity that they never are.
The first thermonuclear device ever exploded was the USA's Ivy Mike, which was detonated during a test at the Enewetak Atoll in the Pacific Ocean on the 1st of November, 1952. It exploded with a force of between 11 and 12 megatons, approximately 534.88 times more powerful than the Fat Man fission bomb.
1 kiloton (KT) = 1,000 tons of TNT
1 megaton (MT) = 1,000,000 tons of TNT (or 1,000 KT)
Reported yields have varied over time, and according to source:
The Gadget (20 KT)
16th July 1945: Exploded as part of the 'Trinity' test, and as such became the first nuclear device ever detonated by humans.
An implosion-type device that used the man-made fissile isotope known as plutonium-239, a material that could be created much more easily than the extremely expensive and difficult process of enriching uranium to weapons grade.
Little Boy (13-15 KT)
6th August 1945: Exploded 580 meters above the city of Hiroshima, Japan. Killing 140,000 people by December 1945, as recorded at the Hiroshima Peace Site.
Even in the early stages of the Manhattan Project, this "gun-type" of weapon was always considered to be very unsafe in terms of handling and delivery. Fire, lightning strike, physical impact from a crash or even an electrical short-circuit were all considered as major drawbacks during it's development. However, due to the lack of available plutonium at the time (the material used in the Trinity test), the decision was made to use 64 kilograms of uranium-235 instead, which necessitated the use of this method of nuclear fission.
Fat Man (20-23 KT)
9th August 1945: Exploded 500 meters above the city of Nagasaki, Japan. Killing 73,884 and critically injuring a further 74,909, as recorded upon the memorial plaque in the Nagasaki Peace Park.
Similar in design to the Gadget device, this bomb converted just one gram of it's total matter into the explosive energy that the city below bore witness to.
Ivy Mike (11-12 MT)
1st November 1952: The first thermonuclear device ever detonated, as part of the 'Operation Ivy' series of tests.
This test was just the first step along the road of working towards a weaponised system. Due to it's massive size and complexity, this was never thought of as a test of a truly deliverable weapon, instead, it was designed as a proof of concept for the hydrogen bomb.
Grapple Y (3 MT)
28th April 1958: The UK's first (fully successful) thermonuclear device was tested, as part of 'Operation Grapple'.
This was the fifth device tested in the Grapple series, after the somewhat disappointing results of the previous attempts, this became the most effective nuclear device ever tested by the British.
Tsar Bomba (50-57 MT)
30th October 1961: The largest bomb ever exploded, and singularly the most powerful man-made device, of any kind, ever utilized in the history of the world.
Developed and detonated by Soviet Russia.
In a comparison to conventional explosives:
1 Megajoule (MJ) = 1,000,000 joules, approximately the energy that a one-ton weight has travelling at 100 mph (160 km/h)
1 Terajoule (TJ) = 1,000,000,000,000 joules, the Little Boy bomb exploded with approximately the force of 60 TJ
One (conventional) 2000lb bomb contains roughly 945lbs (429kg) of explosive material, which in this example is Tritonal; the detonation of which creates 2165 MJ of energy, compared to a 'small' fission explosion of 60,000,000 MJ.
What happens in a fission reaction
Nuclear fission is the process whereby the nucleus of an atom is split into smaller, lighter nuclei. Fission of a heavy element creates an exothermic reaction which means large amounts of heat and energy are released; both as electromagnetic radiation and kinetic energy.
- 235U plus n = 95Sr plus 139Xe plus 2n = 180 MeV
- U = uranium-235
- n = a single neutron
- Sr = strontium-95
- Xe = xenon-139
- MeV = million electron volts (energy)
The above equation essentially means the nucleus of an atom of uranium-235 is hit by a neutron, the uranium then splits into two smaller atoms (called fission fragments) and also two extra neutrons. This means you generate neutrons as fast as you use them in order to create the reaction in the first place, therefore it becomes self-sustaining.
An atom of uranium can be split in many different ways, as long as the atomic weights add up to 236 (uranium plus the extra neutron), the process can continue over and over again.
The first fission bomb ever detonated in anger was Little Boy, which used 64 kilograms of 80% enriched uranium.
What happens in a fusion reaction
Nuclear fusion is the process whereby multiple atomic nuclei are fused together to form a single, heavier nucleus. The reaction will either release or absorb energy, in the case of weaponry the aim is to create a vast release of energy in order to harness it's explosive power. This is mainly witnessed through the effects of thermal and electromagnetic radiation (x-rays being the main force behind the creation of the huge fireballs seen in thermonuclear explosions).
- 2D plus 3T = 4He plus n plus 17.6 MeV
- D = deuterium
- T = tritium
- He = helium-4
- MeV = million electron volts (energy)
During the Cold War, a period of international fear and tension over the use of American and Russian nuclear arsenals against one another, the mutually assured destruction policy was held by the two opposing sides. This idea stated that any one side in a nuclear exchange would always be able to destroy the nation whom fired at them first. This 'second strike' capability was born from advances in submarine-portable ICBM MIRVs (missiles which allowed for long range, multi-target strikes).
It was during this period (1947 to 1991) that both sides amassed huge stockpiles of warheads, bombs, missiles, and methods by which to deliver them to a target. At one point, in 1985, there were approximately 65,000 active weapons in the world, this would be enough to effectively end all human life on the planet several times over.
In video games
- Developed by Atari
- Published by Atari, licensed to Sega for the European release
Originally released in arcades, but subsequent revisions and re-releases have seen it come to PCs and home consoles, it is the earliest video game to feature visual depictions of nuclear weapons.
With the player assuming control of three separate anti-ballistic missile (ABM) batteries, and being tasked with destroying incoming intercontinental ballistic missiles (ICBMs), multiple independently targetable reentry vehicles (MIRVs), and smart bombs. All with only ten ABMs available per battery, and six cities to save from utter destruction.
You cannot win Missile Command, no matter how many cities you save or how high your score is, the game will just keep going until you are obliterated, the final message flashing up on screen being..."The End".
1997 to 2008 - The Fallout series
An iconic series in which the player character must survive and overcome the harsh, post apocalyptic setting of an America devastated by a worldwide nuclear exchange.