Nuclear Power

Nuclear Power

What is Nuclear Power?

The source of nuclear power is from the ‘binding energy', which holds the whole atom together. The result of this is the nucleus being split and a huge amount of energy. The small mass is multiplied by the speed of light squared to get the amount of energy due to E=MC2. The splitting process is called nuclear fission. Not all elements can undergo nuclear fission because the atoms are bound too tightly together. However, atoms like Uranium can because they are not bound as tightly.

How it Works

Nuclear fission works by making a neutron hit an atom (most likely Uranium). The atom absorbs the neutron, but then becomes volatile. It breaks apart and makes two fission products, a giant burst of energy and 3 extra neutrons. A chain reaction then occurs.

History

* 1789- Uranium discovered by Martin Klaproth.

* 1896- Radioactivity was discovered by Henri Becquerel. He noticed that photographic panels underneath lightproof material had been darkened, as if light was shown onto it. A rock containing Uranium was on top of the lightproof material. It turns out that uranium had given out invisible particles.

* 1890- Marie Curie gave the name ‘Radioactive' for the above thing. Also, she found pitchblende without Uranium was still radioactive and named it radium.

* 1902- From this year onwards various scientists experiment to change one element into another by hitting atoms with either protons or neutrons.

* 1911- Frederick Soddy finds that radioactive elements can be used as tracers.

* 1932- James Chadwick discovers the neutron.

* 1942- First controlled and sustain nuclear chain reaction by Enrico Fermi in an American experimental reactor lab. Nuclear weapons testing begin.

* 1945- Hiroshima and Nagasaki bombed by nuclear bombs. Most of each city destroyed. 160000 killed in total.

* 1951- Idaho Falls experimental reactor generates electricity (only enough for four light bulbs).

* 1955- A reactor was built in Obninsk, USSR, 100 megawatts were produced.

* 1956- World's first commercial reactor in Cumbria, UK goes into use.

* 1957- The first large nuclear plant operates in Shippingport, Pennsylvania.

* 1965- First nuclear reactor is operated from outer space.

* 1979- Three Mile Island Accident.

* 1986- Chernobyl Disaster in USSR. One reactor caught fire because the control rod was too slow to lower when a sudden increase in energy output happened in reactor four. It exploded, and radioactive materials spread through wind to the greater area.

The Mining

Most of nuclear fuel comes from Uranium. They are found in ores of either pitchblende or carbontite. Most of these deposits are found in Australia, North America and Congo. Uranium has three isotopes, U-238, U-235, and U-234. More than 99% of natural Uranium is U-238. The best isotope for fission is U-235 but it is very rare naturally. Only small amounts of Uranium are contained in ores, meaning special extraction is needed. One way is to mine the ore, dissolve it in acid, take out the Uranium oxide and send it a conversion plant to convert to nuclear fuel. The other way is solvent extraction. The solvent is put into one of the two holes drilled, it dissolves like the other method and pure uranium comes out the other hole. Plutonium is also used but it's super rare in nature and is normally made in reactors.

The Fission

There are a number of types of reactors for nuclear fission. There are pressurized water reactors, rapid reactors (no moderator), boiling water reactors, heavy water reactors, and Magnox reactor. The main difference is the moderator used for each type. You can see the type of moderator they use by looking at their names. In Magnox reactors, neutrons from the radioactive decay in fuel are slowed by graphite blocks between fuel elements to slow the chain reaction to allow more fissions to happen. Fuel elements (for Magnox) are made of Magnox alloy (to allow more neutrons through) filled with U-238. Fuel elements are fuel in long strips. There are hundreds of them in each reactor. The rate of fissions can be changed by lowering the control rods (normally made of Boron). Control rods absorb the neutrons to slow or stop the reaction. In Magnox reactors, the coolant used is CO2. The coolant heats up when it pasts the fuel, the heat is transferred to the reactor's water. The water boils and produces steam, which drives the turbine, which makes electricity. Vapour then comes out of the funnel.

Spent Fuel

Decayed fuel does not produce as much energy, needing replacement. Spent fuel needs reprocessing so that the Uranium that is not decayed can be extracted and reused. Most of the world's reprocessing plants are in Europe and Japan. There, spent fuel is cooled down for years until it is less radioactive. They are reprocessed by dissolving it in acid, which separates fuel and waste. The waste is then transported in specially designed containers (extra strong to prevent accidents and terrorists) to burial places.

Burial

Highly radioactive wastes are compacted in glass blocks, and buried deep underground. Another way of burial is to put waste into sealed under-seabed tunnels. These all stop waste from leaking into the environment.

Pros

* No air pollution.

* Total life span will use only 1% of fossil fuel plants' energy use.

* Small amount of waste.

* High energy output.

* Good for Australia due to Australia's rich reserves of Uranium.

* Produces lots of energy.

* Helps medically.

Cons

* Uranium radiation changes elements therefore damages cells.

* Life threatening when exposed to high amounts. Illnesses such as cancer, immune system damage, skin damage, organ damage, DNA mutation, which passes on to offspring, can occur

* Takes thousands of years to decay.

* Huge consequences if accidents occur

* Can't meet sudden demand for electricity.

* Expensive to build and maintain.

Uses

* Electricity.

* Atomic Bombs.

* Submarines, to stay under water longer.

* Radioactivity aim and kill bad cells to fight cancer.

* Gamma scans for cancer.

* Radioactive markers track body activity. Different results depending on amount of absorption.

* Spacecraft, when too far away for sunlight.

Future

Current research on nuclear power is mainly on:

* Stable hydrogen power by ramming hydrogen nuclei to make Helium nuclei, which makes energy in the process.

* Reliable high-temperature reactors for faster fission impact (more energy created).

* Burning waste at intense heat to deal with nuclear waste.

Conclusion

Nuclear power is an excellent stepping-stone between non-renewable energy and renewable energy. It is an improvement from coal fire, but it lacks the waste less advantages of renewable energy.

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