Kisah perjuangan seorang sahabat yang kian dilupakan.....

Suhaib Ar-rumi.............

Suhaib adalah seorang pedagang yang pintar dan cerdas, beliau menjual dengan harta dan jiwanya guna mendapatkan redha Allah SWT, maka diapun mendapatkannya dan berhak mendapatkan penghargaan orang Romawi yang mendapatkan kemenangan dalam Islam, dan berhak seperti yang diriwayatkan dari Rasulullah saw :”Suhaib penakluk negeri Romawi”. (HR. Ibnu Sa’ad).


Definition of Nuclear Energy
What is nuclear energy? Nuclear energy is a way of creating heat through the fission process of atoms. All power plants convert heat into electricity using steam. At nuclear power plants, the heat to make the steam is created when atoms split apart. This splitting phenomena of the atoms is what we called fission. Besides than that, there are other types of nuclear power plants that are by burning coal or oil for heat to make steam.
Reaction in Nuclear Power Plant
When there are fissions in the reaction, it will also release energy in the form of heat. The released neutrons can then repeat the process. This releases even more neutrons and more nuclear energy. The repeating of the process is called a chain reaction. In a nuclear power plant, uranium is the material used in the fission process.
The heat from fission boils water and creates steam to turn a turbine. As the turbine spins, the generator turns and its magnetic field produces electricity. The electricity can then be carried to  many houses, so people can work on the computer, watch television, play video games, or even make toast. The most important thing is the government must make sure that the nuclear power plant must be safe for people who work there and live nearby, and for the environment.
In other hand, we must know that the nuclear material is used for many things besides nuclear power for example for detecting and treating certain illnesses. Nuclear material also used to perform research at universities and to help in industries for such things as locating cracks in steel, getting rid of dust from film and even measuring the amount of air whipped into ice cream.
What is Nuclear Reactors
To produce nuclear energy, we need to have a nuclear reactor. So what is nuclear reactor?. A nuclear reactor is a system that contains and controls sustained nuclear chain reactions. Reactors are used for generating electricity, moving aircraft carriers and submarines, producing medical isotopes for imaging and cancer treatment, and for conducting research.
Fuel, made up of heavy atoms that split when they absorb neutrons, is placed into the reactor vessel along with a small neutron source. The neutrons start a chain reaction where each atom that splits releases more neutrons that cause other atoms to split. Each time an atom splits, it releases large amounts of energy in the form of heat. The heat is carried out of the reactor by coolant, which is most commonly just plain water. The coolant heats up and goes off to a turbine to spin a generator or drive shaft. So basically, nuclear reactors are exotic heat sources.
Components of Nuclear Reactors
When we look at the nuclear reactors, there are many components. The main components inside the nuclear reactor are:
1.      The core of the reactor contains all of the nuclear fuel and generates all of the heat. It contains low-enriched uranium (<5 and="" can="" contain="" control="" core="" fuel="" hundreds="" individual="" materials.="" of="" pins.="" span="" structural="" systems="" the="" thousands="" u-235="">
2.      The coolant is the material that passes through the core, transferring the heat from the fuel to a turbine. It could be water, heavy-water, liquid sodium, helium, or something else. In the US fleet of power reactors, water is the standard.
3.      The turbine transfers the heat from the coolant to electricity, just like in a fossil-fuel plant.
4.      The containment is the structure that separates the reactor from the environment. These are usually dome-shaped, made of high-density, steel-reinforced concrete. Chernobyl did not have a containment to speak of.
5.      Cooling towers are needed by some plants to dump the excess heat that cannot be converted to energy due to the laws of thermodynamics. These are the hyperbolic icons of nuclear energy. They emit only clean water vapour.
Types of Nuclear Reactors
There are very many different types of nuclear reactors with different fuels, coolants, fuel cycles, purposes. The example of nuclear reactors are pressurized water reactor and sodium cooled fast reactor.
1.      Pressurized Water Reactor
The most common type of reactor -- the PWR uses regular old water as a coolant. The primary cooling water is kept at very high pressure so it does not boil. It goes through a heat exchanger, transferring heat to a secondary coolant loop, which then spins the turbine. These use oxide fuel pellets stacked in zirconium tubes. They could possibly burn thorium or plutonium fuel as well.
2.      Sodium Cooled Fast Reactor
The first electricity-producing nuclear reactor in the world was SFR (the EBR-1 in Arco, Idaho). As the name implies, these reactors are cooled by liquid sodium metal. Sodium is heavier than hydrogen, a fact that leads to the neutrons moving around at higher speeds.  These can use metal or oxide fuel, and burn anything you throw at them (thorium, uranium, plutonium, higher actinides).
Nuclear Reactor and the Environment
Small amounts of radioactivity can be released into the environment but only under controlled and monitored conditions. The only major accident in a nuclear power plant in this country was at Three Mile Island near Harrisburg, Pennsylvania, in March 1979. At Three Mile Island, there was major fuel damage, and radioactive gases and contaminated cooling water filled the containment building. Some radioactivity was released into the atmosphere, but it didn't hurt people or the environment.
A much more serious accident happened in 1986 at Chernobyl in the former Soviet Union. That reactor was built differently than those in the U.S. Most importantly, it had no containment system. The reactor core was severely damaged and a large amount of radioactivity was released into the environment.

Decommissioning of Nuclear Reactor
Nuclear power plants can be decommissioned using three methods:
  1. Dismantling -- Parts of the reactor are removed or decontaminated soon after the plant closes and the land can be used.
  2. Safe Storage -- The nuclear plant is monitored and radiation is allowed to decay; afterward, it is taken down.
  3. Entombment -- Radioactive components are sealed off with concrete and steel, allowing radiation to "decay" until the land can be used for other purposes.
Radioactive Waste
High-Level Radioactive Waste
High-level waste includes the fuel used in the nuclear reactor -- called spent fuel . It is highly radioactive and very dangerous. It must be cooled for several years in deep pools inside the plant or in special storage facilities outside of the plant site. It can remain in the pool or later be transferred to special casks, which are like big, concrete barrels. Some of the fission products in the spent fuel will take many years to lose their radioactivity. A special disposal site is needed for this type of spent fuel. The U.S. Department of Energy wants to build such a site at Yucca Mountain, Nevada. The spent fuel, in heavy casks, would remain buried there for thousands of years. The NRC must approve and license this site to make sure it is safe.

Low-Level Radioactive Waste
Low-level waste can come from nuclear reactors or from hospitals or universities. Low-level waste is not as dangerous as high-level waste. It can be shipped to low-level waste disposal facilities. There, it is packaged, buried in trenches and covered with soil. States are responsible for selecting new disposal sites or using those that already exist.

Effects of Nuclear Radiation on Environment

Humans and Animals

The effects of radiation on humans and animals are well-documented as having an extremely detrimental effect. When exposed to radiation in large amounts, humans can develop cancer. If the amount of radiation is controlled, it can be used to treat cancer, but if a leak or accidental exposure occurs, it would be nearly impossible to control the exposure. Radiation can also cause birth defects in humans and animals, so an exposure to radiation in the wild could lead to generations of difficulties throughout an entire ecosystem.

Plant Reproduction

One of the largest environmental exposures to nuclear radiation was the Chernobyl disaster in 1986. This accident caused 125,000 square miles in the Ukraine and Russia to be exposed to radiation. One of the largest damaging effects over the next few weeks were the reproductive tissues of the plants. Similar effects have occurred with hydrogen bomb testing in other parts of the world. It took these trees around three years to regain their reproductive abilities. Some scientists believe that three years was much sooner than when they believed the plants would be able to reproduce again.

Nuclear Fusion in Astronomy
In physics and nuclear chemistry, nuclear fusion is the process by which multiple atomic particles join together to form a heavier nucleus. It is accompanied by the release or absorption of energy. Iron and nickel nuclei have the largest binding energies per nucleon of all nuclei and therefore are the most stable. The fusion of two nuclei lighter than iron or nickel generally releases energy, while the fusion of nuclei heavier than iron or nickel absorbs energy. The opposite is true for nuclear fission. Nuclear fusion is naturally found in stars.

Nuclear Reactor. Retrieved on May, 1, 2012

Report on Nuclear Energy Usage. Retrieved on May, 1, 2012

Review oh the Usage of Nuclear Energy. Retrieved on May, 1, 2012

No comments:

Post a Comment