Nuclear energy

• It is one of the most modern energies and it´s very controversial. As the others, it has got positives and negatives points.

INTRODUCTION

• The nuclear energy is obtained by two ways: by the fusion and the fission. The first one is in investigation and it´s obtained in laboratories. The fission is the one it´s used in the nuclear central.

HISTORY• All started with the famous Einstein formula:

E=MC2, where E is the energy released, M the difference in mass or increase and C the speed of light. The first use was the bomb, where was released 12 kilotons of energy (equivalent to 12 tons of TNT), destroying a city. That is a form of uncontrolled energy release, instead on the nuclear centrals that the amount released is much smaller and more controlled.

• In the 70´s, it was a big economic crisis, where the use of oil decrease. That promote the construction of the first nuclear central in the world, they use uranium as fuel.

• Nowadays in the world exist around 450 reactors in the world, that originate 16% of the world energy. The first nuclear central in Spain was built in 1968 and actully there are 9 nuclear reactors in 7 nuclear centrals in all Spain.

FISSIONIt´s use nowadays in the nuclear centrals. When a heavy atom as the uranium and plutonium are bombarded, form smaller atoms and neutrons that desprende the energy, verified Einstein´s formula. That is produced because the uranium 235 picks one electron and it becomes uranium 236 that it´s very unstable, releasing electrons and so a lot of energy.

• In that process, se desprenden energy in form of heat. That heat, heated some water pipes, and this becomes in steam, that steam passes through the turbines, making them turn. These together, turn an electric generator in a given power, generating electricity. Logically, you don´t get all the energy in the fission, and you lose part of the energy in heat, lead resistance, vaporization, etcetera.

FUSIONThe nuclear fusion, nowadays it´s in investigation, because now it´s not viable, because you use more energy than you acquire in this process. La fusion is a natural process in the stars, in there occur the nuclear reactions by fusion, because there are high temperatures in the stars, that are compounds of Hydrogen and Helium. The hydrogen, in normal conditions of temperature, is repelled each other when you try to unite them, due to electrostatic repulsion. The hydrogen crash and they make a lot of energy.

ROLE OF NUCLEAR POWER In nuclear plants, the process being controlled is the end,

because in them, energy is generated slowly, otherwise the reactor would become a bomb, because most of the energy is releasedthe end.Uranium rods enter the reactor and a fission process begins. In the process, energy is released as heat. This heat, heat some water pipes, and this is converted into steam, which passes through turbines, turning them, thus generating electricity.

ADVANTAGES OF NUCLEAR ENERGY

• The nuclear energy generates third of the electric power of Europe thereby avoiding the emission of 700 million tones of CO2 per year into the atmosphere. On the other hand, it also prevents other emissions of pollutants that are generated in fossil fuel use.

• Discharges from nuclear power plants abroad, can be classified as minimal, and come, as a gas from the chimney of the plant, but are expelled large amounts of air, and little radioactivity; and liquid through the discharge channel. Because of its low polluting power, nuclear power plants, curb acid rain, and the accumulation of toxic waste into the environment. As data: a nuclear plant can not dump into the atmosphere more than 3 curies per year, according to current regulations (1 CURIO = 37,000 million radioactive disintegrations per second = 1 gram of Radio).

• In addition, lower consumption of fossil fuel reserves, generating very little fuel (uranium) a lot more energy, thus avoiding transport costs, waste, etc..

DANGERS OF NUCLEAR ENERGY

Currently, the nuclear fission industry, presents many dangers, that by now they have a quick solution. These dangers, they can have a major impact on the environment and in living if they are released to the atmosphere or spills on the environment, even to cause death, and condemn future generations with mutations .. . Therefore, the nuclear plants are required a large security measures that can avoid these incidents, although they may sometimes become inadequate (Chernobyl), because they are trying to save money in construction, and only puts minimal security.The major hazards are among others, radiation and the constant risk of a possible nuclear explosion, although the latter is very unlikely with the current systems of nuclear power plant safety. We will focus mainly on radiation, being the most representative, because the explosions are very unlikely.

Nuclear Warnings• Currently, the nuclear fission industry, presents many dangers,

that by now they have a quick solution. These dangers, they can have a major impact on the environment and in living if they are released to the atmosphere or spills on the environment, even to cause death, and condemn future generations with mutations .. . Therefore, the nuclear plants are required a large security measures that can prevent such incidents. We distinguish two cases; natural radiation and artificial radiation.

THE RADIATION

• Radioactivity is the property whereby certain elements found in nature, such as uranium, are transformed, by emission of alpha particles (helium nuclei), beta (electrons), gamma (photons), in others new elements that may or may not, turn radioactive. Radioactivity is therefore a natural phenomenon to which man has always been exposed, but are also artificial radiation. Thus, we differentiate two cases, natural radiation and artificial radiation.

1-Natural radiation• It has always existed, and that comes from existing materials in

the universe, and may be visible radiation (eg light) or invisible (eg UV). This radiation comes from cosmic radiation from outer space (sun and stars).

• This natural radiation is approximately 88% of the total radiation received by humans, classified as follows:   

• - Cosmic radiation : 15%  - Radiation from food, drink, etc.. : 17%  - Radiation from natural elements : 56%

SAFETY AND RADIATION PROTECTION OF THE CENTRAL NULEARES

  - Fuel rod: Zirconium alloy tubes inside of which is uranium. - Reactor vessel: cylindrical carbon steel, coated stainless steel

interior, 12.5 cm thick, with 18.5 meters high and 4.77 meters in diameter. Inside is the reactor core, where you get the steam that spins the turbine.

- Reactor building: It is a reinforced concrete structure of 1 meter thick and 55 meters high (12 of them underground). It is designed to withstand accident conditions more possible.

 

EMERGENCY SYSTEMS

En caso de emergencia, se activarían los siguientes Sistemas de emergencia. Se activan al romperse la tubería de refrigeración, y es un sistema autónomo automático, y se compone de:  

  - Inyección del Refrigerante a alta presión :Inyecta refrigerante al interior de la vasija, justo encima del combustible.

- Rociado del núcleo - Inyección de refrigerante a baja presión :Inyectan refrigerante a

la vasija, inundando el núcleo. - Sistema automático de alivio de presión: Impide la presurización

de la vasija por encima de los valores operacionales. - Condensador de aislamiento: Enfría el vapor existente en la

vasija. - Inserción de las barras de control :Al insertarlas, se para

totalmente el reactor.

Containment barriers of a nuclear power

It can be seen in the same way security systems at their disposal nuclear power plants.    

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SPANISH NUCLEAR CENTRALS