NUCLEAR   ENERGY (URANIUM) ATOMIC  ENERGY

In 2001, there were around 60 nuclear power plants in U.S.A, mostly located on the East and Midwest. The power generated from these plants were 20 per-cent of total energy produced in this country, which is equal to consumption of energy in Texas, New York and California. A nuclear power plant uses uranium to generate heat. This heat turns water into the steam which it moves the big turbines to generate electricity. The heat comes from breaking the uranium. The chamber that uranium is spited is called reactor core. 

NUCLEAR FUEL

Protons, neutrons and electrons are three elements of an atom. When an atom, (specially fissionable one like uranium- u-235) is split, heat is being released. This type of uranium is used in nuclear power plants, as fuel, to generate electricity. when uranium is found in mines, the u-235 type of it  should be extracted and enriched before the usage in power plants. The final processed product is about one inch long. This amount of uranium can generate as much electricity as one ton of coal.

TYPE OF REACTOR

There are many types of nuclear power plants. In the U.S.A,they use two types of reactors called boiling-water reactor(BWR) and pressurized – water reactor (PWR). In boiling water reactor, reactor core makes enough heat to change the water into steam, then the steam turns the turbine on to generate energy. But in pressurized water reactor water around the core is pressurized in a way that it does not change into the steam. Meanwhile elsewhere, the steam is generated inside another device. Then it passes through the turbines and makes it turn. Inside this huge generator there are thousands of tubes, which hot radioactive water, are passed through. Outside the tube, there is clean water which absorbers  the heat generated by the tubes. This clean water then changes into the steam. The radioactive water then goes back to the reactor to be heated by the tubes

In brief, the main function of a nuclear reactor is to release heat at a controlled pace. The heat then changes water to steam, which turns the turbine on to generate electricity. Then after production they distribute it, so to be used by different factories, houses and so on.

The reactor core is composed of some parts, which are called the fuel, the control and the moderator. The fuel is consisted of enriches uranium dioxide placed in 3.6 meter long metal tube. The control rods regulate the chain reaction. The coolant, which is basically water, carries away the heat generated in the reactor.

The moderator, allows the atom of uranium to split with proper speed. When the atom is spilt, it releases the energy.

ENVIRONMENT

A nuclear power plant like other plants produces wastes, which are radioactive and dangerous. But it does not release carbon dioxide. The amount of carbon dioxide not released by power plants in U.S.A is equal to emission of this gas by 5 billion cars.

These wastes or residuals are those materials, which are contaminated during the electricity generation process. The environmentalists are very concerned about these materials. They have very tight control over these wastes. They never expose to open air. At this time these wastes are kept in concrete containers, But U.S.A government has plan to deposit the fuel residuals beneath the mountain somewhere at Yucca, at the state of Nevada.

NUCLEAR POWER GENERATION

Before the 20^th century the main source of generating electricity were coal, and gas. The first nuclear power plant started its operation in 1957 in U.S.A at Pennsylvania. Many nuclear plant were built afterwards. In 2002 the total nuclear electricity generated, exceeded 780 billion kilowatt hours, which was 1.5 percent more than the production of the year before. It is worth mentioning that the production was 600 billion kilowatt hour in 1991.

Although the production increased over 30 years, but the total number of power plants decreased from 111 in 1990 to 104 due to safety requirements. Now they are operating more efficiently than before. In January 2002 the nuclear energy generated by these plants passed the level of 71 billion kilowatt hour, the highest level ever produced in the U.S.A. Nuclear plants are based on the process of nuclear fission. Nuclear fission is a process that a nucleus of heavy element, like uranium splits when hit by free neutron in the reactor. This process will release two smaller atoms, also one two three neutrons plus some heat. In this process since many neutrons are released, the bombarding of the uranium atom continues and becomes a chain reaction. If this process takes place under control condition, too much energy will be released well enough to produce electricity.

Basically, uranium comes with other elements, and may be found in western U.S.A, Australia, Africa, South America or other places.To extract  the uranium, it must be commercially approved. One ton of uranium ore produce only 7 pounds of uranium dioxide, which then should be processed and formed into pellets. These pellets then are placed in fuel rods. These rods are placed together to form fuel assemblies.

Along these rods they place another rods called controlled rod, then the whole rods are put into water in the reactor to produce heat. The heated water turns into the steam, which rotates the turbine blades, connected to an electric generator.

The U.S.A is ranked first in producing nuclear energy. France, Japan, Germany, is placed 2^nd to 4^th. In some countries like U.S.A the growth of commercial production of nuclear electricity has been reduced since 1978, but some countries like South Korea or China stepped up their nuclear production.

Environmental concern about nuclear wastes, and high cost of closing a nuclear plant are puzzling. Mean - while the advantage of these plants over fossil fuel generators, which release dangerous gases into the atmosphere and pollute the environment may influence the growth of nuclear plants in the future.