Реферат по предмету "Иностранный язык"


Physical And Environmental Effects Of A Nuclear

War Essay, Research Paper

Imagine the heat of millions of degrees, the immediate destruction of thousands of acres, and the deaths of hundreds of thousands of lives. Now imagine all of that times a thousand. There you have a nuclear war, the explosion of a thousand or more nuclear bombs on the earth. That is what is estimated would be a nuclear war. All of that power packed in relatively small(considering the power they unleash) bombs. The results of a nuclear war would be devastating. It would be devastating to the health and lives of people, and to the environment in which we live. The world wouldn’t fully recover for hundreds of years.

How a nuclear weapon works

In a modern nuclear bomb, commonly called a thermonuclear bomb or a H-bomb, fusion is the power behind the explosion and destruction. Fusion is the fusing of the nuclei of two atoms, which produces an extreme amount of energy(about 40 times that of a fission reaction). For fusion to occur, though, an extremely high temperature and pressure must first be reached, and this is achieved by fission(splitting of the nucleus of an atom). The detonation of a fusion weapon begins with the detonation of a conventional explosive that sets off a fission reaction explosion. Plutonium and uranium are used to create fission. The atoms fused are those of the isotopes of hydrogen, deuterium or tritium. The fusion and fission from a thermonuclear weapon result in large amounts of radiation that can be fatal to humans and animals and can also cause many other effects.

Short-term physical effects

One short-term effect of a nuclear war would, of course, be the deaths of millions of people. It has been estimated that an attack on U.S. populations centers by 100 one-megaton nuclear weapons would kill up to 20 percent of the population immediately through blast, heat, ground shock, and instant radiation effects. Also, and attack with 1,000 one-megaton nuclear weapons (which many say is more realistic than just 100 weapons) would destroy immediately almost half the U.S. population.

Those that do survive the initial explosions would be far from out of the clear. Those estimates above do not include the additional deaths from fires, starvation, or the lethal fallout showering to the ground downwind of the explosion. Skin burns, acute radiation sickness(which includes nausea, vomiting, diarrhea, and fever), and noticeable blood changes are just a few of the effects of radiation on the body.

One way to measure radiation is in Rads. The lethal dose for 50% of the exposed population for humans is 400 Rads. Here are some short-term effects of different doses of radiation:

0-25 Rads-No apparent short-term effects.

25-100 Rads-Blood changes are noticeable.

100-200 Rads-Some toxic symptoms of weakness, fatigue, nausea, vomiting, diarrhea, fever, and infection. Hair loss, skin spots, hemorrhaging, and some instances of heart failure may also occur.

200-450 Rads-Symptoms are the same as the previous exposure level, except that they are more extreme. Will prove fatal to 25-50% of those exposed.

450-600 Rads-Symptoms of previous level only even more sever and sooner. Illnesses include mouth, throat and skin hemorrhages. Will prover fatal for 50-75% of those exposed.

600-800 Rads-Previous symptoms plus circulatory and nervous system failure. Medications can control some of the symptoms and make the patient more comfortable, but can’t defy the inevitable. 100% of those exposed will die.

How far the nuclear fallout travels and the doses those who are in range of the fallout receive depend on weather and other such conditions. It has been estimated that an explosion of a one-megaton nuclear weapon at ground level in 15 mph winds would produce fallout extending hundreds of miles downwind. At a distance of 20-25 miles, a lethal radiation dose (600 Rads) would be accumulated.

Long-term physical effects

Those that survived the explosion and the fallout that followed would still have to deal with effects for years. Exposure to radiation increases a person’s chances of cancer, and also decreases life-span. Another long-term effect would be genetic damage. Radiation can alter the sperm or egg cells in a person, which may result in different genetic diseases. These effects may appear in the exposed person’s direct offspring, or may appear several generations later, depending on whether the altered genes are dominant or recessive.

Short-term environmental effects

In nuclear explosions, about 90 percent of the energy is released within one millionth of a second. Most of this is in the form of heat and shock waves. When a weapon is detonated at the surface of the earth, the heat vaporizes nearby structures and underlying soil and rocks. Anything within a 3-4 mile radius doesn’t have a chance.

Below shows a photo sequence of a wood framed house exposed to a nuclear blast. This part. Realize that this particular test explosion was very small. In fact, the explosion only had about 1/4 the power of the bomb dropped in Hiroshima(which was only a fission bomb).

All of the buildings and material that the bomb vaporizes ascend into a fast-rising fireball. As the fireball rises, it expands and cools, producing the mushroom cloud that the signature of nuclear explosions. The cloud will punch into the stratosphere(begins 7 miles up). The heavier particles will fall back to earth, but the lighter particles will remain there for months or even years. It is estimated that a 10,000-megaton nuclear war would tear up 25 billion cubic meters of rock and soil, with the fine dust being injected into the stratosphere. In comparison to this, when Krakatoa an Indonesian volcano erupted in 1883, sunsets around the world were noticeable reddened for years, suggesting that large amounts of the volcanic dust had entered the stratosphere. A 10,000-megaton war would inject twice the material as the volcano did. Changes in temperature and sunlight would affect crop production.

Long-term environmental effects

The long-term environmental effects of a nuclear war are probably not as drastic as one may think. Many myths include ideas like: “In the event of a nuclear war, the earth will be uninhabitable for thousands of years” or “there will be no use trying to survive a nuclear war because when you come out of your shelter, the earth will be totally devastated.” These statements are untrue. They say that the earth would be uninhabitable because of the radiation. Realistically, the radioactive fallout from a nuclear weapon decays pretty fast. It is true that there are some radioactive particles that may pose a threat to the environment in further future, but they would not pose as much of a problem as one may think.

One long-term effect that would be present is the effect on the ozone. If a 10,000- megaton war would take place, it is estimated that as much as 30-70 percent of the ozone might be eliminated from the northern hemisphere. The ozone is what protects us from harmful ultraviolet rays. The ozone cannot be repaired, when it is gone it is gone. With this much of the ozone taken away, there could be incapacitating cases of sunburn and snowblindness in some northern countries.

There is so much that is unknown about what the effects of a nuclear war would be. There are so many possibilities. Some used to think that worldwide accumulation of radioactive fallout would eliminate life on the planet, or that it might produce monstrous genetic mutations in living things, making future generations unrecognizable. But we have learned that these hypotheses are not realistic. There are so many estimates about what would happen in a nuclear war, but no one can really predict it.

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