Radioactivity, nuclear fission and nuclear fusion

What is Radioactivity

Matter can go through physical and chemical changes .  An example for a physical change is the transformation of water into the gaseous state or solid form (ice and steam, respectively), for a chemical change, to add salt to the water. Well, besides these, the matter may experience changes that modify the structure of their atoms at the nuclear level. These phenomenal changes occur as radioactivity, nuclear fission and nuclear fusion.

Radioactive elements: alpha, beta and gama

Radioactivity in the nucleus of certain unstable elements  spontaneously emit particles called alpha, beta and gamma. These elements are classified under the name of radioactive isotopes. They produce very high energy  and it is known as radiation.

Dangerous radioactivity

Living beings can receive radiation from different sources, such as ultraviolet radiation from the sun which they perceive as light or heat and radiation emitted by televisions, radios, hair dryer and other appliances. In the latter waves have low energy and longer wavelength.

But other dangerous radiation like X-rays, the cosmic, ultraviolet radiation or gamma rays, have lots of energy and its wavelength is short. This belongs to the dangerous radioactivity.

Nuclear fission

Nuclear fission is a change through which the nuclei of certain large isotopes (mass isotope) as uranium 235 are divided into smaller unstable nuclei. When struck by neutrons and energy, they produce what is known as a chain reaction. It is called as chain because each fission produces two or three neutrons, and in turn, it may cause a new fission. For this phenomenon to occur there need to be enough cores capable of fission, since they provide the mass needed to capture neutrons.

In the atomic bombs, what happens is that nuclear fission. It causes the explosion of two isotopes of mass, and they begin to collide with each other and thereby produce a chain reaction, which by the way, lasts a fraction of second.

Today many power plants take advantage of nuclear fission for energy. In these plants, the nuclear reactors have control over nuclear fission chain reaction. The energy as an outcome of this phenomenon is used to produce high pressure steam which is used to drive turbines of generators, which in turn produce electricity.

Nuclear fusion

In nuclear fusion two light atoms, such as hydrogen, merge (coalesce) to form a heavier nucleus, in this case helium would be obtained. To achieve this, we have to use high temperatures, as high as one million degrees Celsius.

Mechanism is more difficult than nuclear fission, but once started, it generates more energy and heat.

The military industry has also taken advantage of these properties of the material for building extremely dangerous thermonuclear weapons, such as hydrogen bombs.

Due to depletion and scarcity of fossil fuels, such as oil, alternatives have been sought to obtain energy but nuclear fusion is not useful to generate electricity even though it has been attempted.

Nuclear energy applications

Nuclear Power Plants (Electricity Generation)

Nuclear Power Plants use radioactive elements such as uranium, plutonium or thorium to generate electricity. The radioactivity of these compounds can be controlled to start a chain reaction with no adverse consequences. First a pile of uranium (or any of them) is placed and the mechanisms which generate heat for long periods are activated. This period differs from a normal explosion, because its energy release occurs in fractions of a second. Nuclear reactor is designed for controlling the reaction by the technological characteristics of it. Within the process the heated elements pass through a coolant (such as water) which makes steam. This steam in turn serves to move a turbo-generator that produces electricity.

The reactors are very large constructions formed by graphite blocks. This material serves to enclose the neutrons produced by the fission and prevent dangerous leaks. Graphite is “lined” with a concrete wall about two meters thick and mounted inside the rods or tubes which house the radioisotopes.

The reactor is connected to a water reservoir, the heat exchanger and then to the turbines and generators.

Industrial Application of nuclear energy

Radioactive isotopes are used in some industries for food preservation, crack detection in metals with machines that were built as rail cars, and also serve to know how to distribute a fluid in a pipeline. In the latter case, what is done is to add a small amount of radioactive substances into the pipe and the path of the substances over very long distances can be traced through an accessory called Gauge counter.

Radioactivity is also used to determine the age of fossils or stones, through utilizing elements such as carbon 14.

 

Medical Application of nuclear energy

The radioactivity is very useful for the treatment of some diseases. The patient undergoes controlled radiation with beta and gamma rays impinging on the damaged tissues. This technique is more efficient than X-rays because their actions can go directly and exclusively to the affected tissue without touching healthy tissue.

Some examples of medical usage of radioactive elements are radioactive iodine, which is used to treat thyroid disorders, radioactive phosphorus, for cancer of the bone and to localize radioactive sodium malignancies.

 

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