A nuclear explosion is not always the greatest fear one faces. Radioactive fallout can be of more concern then the actual nuclear blast itself. Once a fission bomb explodes, the metals in the surrounding Earth become radioactive. These newly transformed elements then decay over the next few days releasing both alpha particles and gamma rays. Within seventy-two hours the majority of the elements have gone through enough half-life cycles to render them stable. About ninety percent of the gamma radiation will have dispersed within the first few hours of exposure. Ninety percent of the remaining substance will have dissipated within three days.   These are known as activation products. Additionally, there are many more things that constitute the fallout plume.

Fusion bombs, also known as hydrogen bombs or thermonuclear bombs, employ fusion reactions in order to achieve large atomic explosions. Fusion is when two molecules or ions combine and release energy in the form of light and heat and raw energy. There are many steps that have to occur in order for a hydrogen bomb to detonate successfully. Initially, there is a core of Uranium-235 that is struck by a bullet made up of the same substance. Once conventional explosives are set off, the bullet is sent down the chamber into the core.  This action results in a fission reaction. The heat and energy released from this reaction then initiates the fusion of deuterium or lithium (depending on what was used) into tritium.  This fusion reaction releases immense amounts of energy. The yield generated from this method exceeds 10,000 kilotons. The efficiency is up near 90%.

Nuclear fission is one of two processes in which massive amounts of energy are released. Fission deals with the splitting apart of molecules. In order for a nuclear fission reaction to take place, a few things must in order. The right amount of fuel must be used such that when combined, a critical mass is met; meaning the minimum amount of material needed is present. Once the reaction begins, the fuel (usually Uranium-235) begins to break down, releasing neutrons, heat, and energy. The neutrons that are released collide with other Uranium molecules, causing a chain reaction. This chain of event is what leads to the large explosion resulting from nuclear detonations. The first method for combining the two subcritical methods is the gun and barrel technique. This method uses explosives to send one portion of the Uranium-235 down a barrel into a larger block or Uranium. This then starts the fission reaction that then results in an explosion.

There are many different types of nuclear bombs, varying from the bullet and barrel style of nuclear fission, to others such as the fusion style. The bombs that employ fission use the process to break up uranium atoms, and in turn releasing energy. The other type of bomb employs fusion, combining certain elemental ingredients, in turn releasing massive amounts of energy. When compared, fusion bombs are far more powerful. The energy released when molecules are combined exceeds the energy released upon the breaking of bonds.

More specifically, the barrel and bullet type weapon employs a barometric detonator behind a conventional explosive. The barometric detonator was to go off at a certain pressure. Once the pressure outside the weapon was equal to the pressure within, the bomb was put in motion. Contrary to popular belief the bomb doesn’t go off when it hits the ground, its detonated while still in mid-air. The conventional explosive then propels the uranium projectile down a short barrel towards a nuclear fuel pinhead. Once these come together a rapid chain reaction occurs, resulting in a very large explosion. The splitting of uranium atoms releases a lot of heat and energy.

On a different note, fusion bombs employ a very different system. In these systems, neutrons are fired at lithium deuteride, which results in a helium atom as well as deuterium. This newly made deuterium can then react with tritium. The end products of this reaction are a helium atom and a single neutron. This reaction happens along a chain, and immense amounts of energy are released. The amount of energy released from the fusion of atomic particles is far more than the energy released from breaking them up.

Additionally, if either of these types of weapons is encased in a jacket of cobalt, the amount of radiation released after detonation multiplies extensively. It’s been said that if too many of these weapons are detonated, nearly all life on Earth would disappear. The weapon would employ both fission and fusion. Instead of generating a fast force by the breaking down of uranium, the cobalt is rather transmuted into a more stable form. This process releases damaging gamma rays. The wavelength of gamma rays is so short; they can pass through nearly everything. They can aid in the cause of malignant tumors, and full blown cancers. It’s pretty evident that we as a collective cannot allow for things such as these to be constructed. Global massacre is the only logical end.

Source: http://physics.info/weapons/

Nuclear weapons have long been discussed as the most pertinent human issue. Weapons of this magnitude can’t be taken lightly. Their potential to cause extreme amounts of damage lay far too high. The issue lies not just with the initial blast associated with the nuclear weapon, but also the radioactive fallout that ensues shortly thereafter. The combination of a large intense thermal blast with intense pressure and radioactive fallout causes nearly complete destruction.

A radius of 1.2km is estimated to be the distance in which thermal winds can reach an excess of 800kmh and pressures exceeding 10psi. Within the first several hundred meters everything is vaporized instantaneously. As you get farther and farther away from the detonation point, the chaotic winds decrease, as well as the pressure. However, with increasing distance comes the greater potential for radioactive fallout. The mushroom cloud left behind after the explosion is filled with various decaying substances. These substances are very toxic to the human body as well as any life in general. The toxins interfere with genetic code, usually leading to tumors, cancers, and other genetic mutations.

The way in which nuclear weapons work depends on the system used. There are two ways to harness and release nuclear energy. There is a process called fission in which a substance with large unstable particles is bombarded by free-floating neutrons. Once the neutrons collide with the fuel (usually uranium or plutonium) a chain reaction begins where atoms break down and mimic radioactive decay but at a much more rapid pace. The energy release is nearly instantaneous and very intense. Another way energy is released from nuclei is through nuclear fusion. This is a process by which different atoms are fused together. The binding energy is less for larger particles then it is for smaller ones. Thus, when atoms fuse together, energy is released. If this is done on a big enough scale, it can result in a nuclear explosion.

In addition to these processes, it’s also known that the neutrons produced can be lost from the material or reabsorbed by other nuclei. If an assembly’s rate of production and loss is negative, the set is said to be subcritical. If the rates are equal in value then the set is said to be critical. Lastly, if the rate is positive, the set is said to be supercritical. Ideally, a nuclear weapon should have a positive rate so the chain reaction speeds up with time. This allows for the most energy release.

Lastly, perhaps the most devastating aspect to nuclear weapons, is their ability to block out the sun. The smoke, dust, and other debris can cloud the skies for days, or even weeks, causing dramatic weather changes, even climate changes. The damage from a nuclear weapon doesn’t stop at the blast, but rather 6-12 months after the fires have subsided. The remains consist of nuclear fallout and a traumatized terrain. The effects can be everlasting, leaving vast communities scarred, and changed forever. We as a nation and as people, need to be aware of the fact, that we can cause global destruction with the flick of a button.

Sources: www.nucleardarkness.org/nuclear/

I plan to post about Nuclear Weapons as the semster progresses. I’ve always been curious as to how they actually work with regaurd to physics. I found a site that’s turning out to be very imformative. http://www.fas.org/nuke/intro/nuke/index.html 

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