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NUCLEAR ENERGY

Most nuclear reactions are not radioactivedecay including Fusion and Fission.

Fusion

Fusion is a nuclear process in which two lightnuclei combine to form a single heavier nucleus.A loss of mass occurs and the loss of mass inthis experiment is accompanied by a release ofenergy. An example of a fusion reactionimportant in thermonuclear weapons and infuture nuclear reactors is the reaction betweentwo different hydrogen isotopes to form anisotope of helium:

2H + 3H 4He + n

Demonstration: http://www.youtube.com/watch?v=0TzIJz4_kYI

This reaction liberates an amount of energymore than a million times greater than one getsfrom a typical chemical reaction. Such a largeamount of energy is released in fusion reactionsbecause when two light nuclei fuse, the sum ofthe masses of the product nuclei is less than thesum of the masses of the initial fusing nuclei.

Once again, Einstein's equation, E=mc2, explainsthat the mass that is lost is converted into energycarried away by the fusion products.

Even though fusion is an energeticallyfavorable reaction for light nuclei, it does notoccur under standard conditions here on Earthbecause of the large energy investment that isrequired. Because the reacting nuclei are bothpositively charged, there is a large electrostaticrepulsion between them as they come together.Only when they are squeezed very close to oneanother do they feel the strong nuclear force,

which can overcome the electrostatic repulsionand cause them to fuse.

Fusion reactions have been going on forbillions of years in our universe. In fact, nuclearfusion reactions are responsible for the energyoutput of most stars, including our own Sun.Scientists on Earth have been able to producefusion reactions for only about the last sixtyyears. At first, there were small scale studies in

which only a few fusion reactions actuallyoccurred. However, these first experiments laterlead to the development of thermonuclear fusion

weapons (hydrogen bombs).Fusion is the process that takes place in stars

like our Sun. Whenever we feel the warmth of theSun and see by its light, we are observing theproducts of fusion. We know that all life on Earthexists because the light generated by the Sunproduces food and warms our planet. Therefore,

we can say that fusion is the basis for our life.

Fission

Fission is a nuclear process in which a heavynucleus splits into two smaller nuclei. Anexample of a fission reaction that was used in thefirst atomic bomb and is still used in nuclear

reactors is

235U + n 144Ba + 90Kr + 2n

Demonstration: http://www.youtube.com/watch?v=tQa4LONy9XM

The products shown in the above equation areonly one set of many possible product nuclei.Fission reactions can produce any combinationof lighter nuclei so long as the number of protonsand neutrons in the products sum up to those in

the initial fissioning nucleus. As with fusion, agreat amount of energy can be released in fissionbecause for heavy nuclei, the summed mass ofthe lighter product nuclei is less than the mass ofthe fissioning nucleus.

Fission occurs because of the electrostaticrepulsion created by the large number ofpositively charged protons contained in a heavynucleus. Two smaller nuclei have less internalelectrostatic repulsion than one larger nucleus.So, once the larger nucleus can overcome thestrong nuclear force which holds it together, it

results in fission. Fission can be seen as a "tug-of-war" between the strong attractive nuclearforce and the repulsive electrostatic force. Infission reactions, electrostatic repulsion wins.

Fission is a process that has been occurring inthe universe for billions of years. As mentionedabove, we have not only used fission to produceenergy for nuclear bombs, but we also usefission peacefully everyday to produce energy innuclear power plants.

UTILIZATION OF NUCLEAR ENERGY

The utilization of nuclear energy may haveboth advantages and disadvantages.

Nuclear power stations use relatively

small amounts of fuel and generateelectricity in large quantities.

The reserves of nuclear fuel are

relatively large.

Radioactive emissions are ionizing

radiations and can cause damage toliving cells. In particular the radiationmay damage cells in such a way thatthe person gets cancer or has a child orbirth defects.

Heavy doses of radiation can kill living

things or cause bad burns.

Accidents can occur in power stations

that may cause the release ofradioactive material.

http://www.youtube.com/watch?v=0TzIJz4_kYIhttp://www.youtube.com/watch?v=0TzIJz4_kYIhttp://www.youtube.com/watch?v=tQa4LONy9XMhttp://www.youtube.com/watch?v=tQa4LONy9XMhttp://www.youtube.com/watch?v=0TzIJz4_kYIhttp://www.youtube.com/watch?v=0TzIJz4_kYIhttp://www.youtube.com/watch?v=tQa4LONy9XMhttp://www.youtube.com/watch?v=tQa4LONy9XM

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The sun is essentially a natural thermo-

nuclear reactor.