Nuclear Physics GCSE

Radioactive decay/Background Radiation:

• The three main types of radiation are alpha, beta and gamma.
• Background radiation is all around us and most of it comes from natural sources or medical supplies. This includes cosmic rays, animals, rocks (which emit radon) and plants. Human activity has added to background radiation artificially through X-rays and nuclear weapons testing.
• The reason alpha radiation decays is if the nucleus has too many protons, Helium is emitted to try reduce all the protons repulsing from each other inside the atom. Helium nuclei are continuously in collision with the walls in a nucleus, making it easy to be emitted.

• Beta decay occurs when the neutron to proton ratio is too great, causing it to be unstable. The neutron is turned into a proton and an electron (which is emitted).
• As the neutron changes to a proton, the mass number of an unstable nucleus stays the same but the atomic number goes up by one.
• Gamma decay occurs when the nucleus has too much energy, a gamma particle is emitted as the nucleus falls to a lower energy state. As gamma has no mass and is uncharged, the structure of the atom does not change.

Nuclear Fission/Facts:

• Fission was discovered in 1934 by Enrico Fermi where uranium was split.
• During the process of nuclear fission, a neutron will target the nucleus of a uranium atom causing it to split into several ‘fragments’ and two/three neutrons, the fragments are about equal to half the original mass.
• Warmth, and gamma radiation is released due to the massive amount of energy, which last for a long time.
• A chain reaction takes place as the neutrons are able to split other nuclei causing many other nuclear fission. Chain reactions (controlled) can be used to produce electrical energy in a nuclear power plant. An atomic bomb results from an uncontrolled chain reaction.

Turning nuclear fission into electrical energy:

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Nuclear Fusion:

• In nuclear fusion, when two atoms join together to form one heavier nucleus, energy is released. In the reactor hydrogen atoms come together to form helium atoms, a substantial amount of energy and neutrons.
• It’s the same power that fuels the stars, hydrogen bombs (one could destroy the whole of London) and the sun.
• Fusion reactors offer major advantages over other power sources, it offers lots more power, safer and cleaner (will not leak radiation) and it will produce less radioactive waste.
• The nuclei must come together when hydrogen atoms fuse. However, as there are protons in each nucleus, the same charge tends to repel. Special conditions must happen to prevent this:
• High pressure – this is to squeeze the atoms together - intense magnetic fields/powerful lasers/ion beams may be used.
• High temperature - this is to give enough energy to overcome the protons repulsion, at these temperatures hydrogen is plasma.
• Heavy hydrogen (also known as Deuterium) is a stable isotope of hydrogen found naturally in earth.

Examples/Facts about Nuclear Energy:

• Nuclear energy has one of the lowest environmental impacts compared to other electricity sources. E.g. to produce the same amount of power as a 1000 mega-watt nuclear power plant, a wind farm would need to use up 235 square miles of land.
• The UK has 19 nuclear reactors generating 1/5th of its electricity.
• Nuclear Power is actually a lot less environmentally damaging than most people think. Coal fired power is many thousands of times more dangerous and harmful to the environment than nuclear power.
• Atomic bombs are made by an uncontrolled chain reaction in nuclear fission. This was dropped in Hiroshima and killed 140000 people to get them to surrender.
• The first commercial nuclear power station started operating in the 1950s.
• The fission of an atom of uranium produces ten million times the energy produces from combustion of an atom of carbon from coal.
• In France, nuclear power supplies 80% of the countries electricity.
• In the early hours of the 26th April 1986, one of the four nuclear reactors at Chernobyl exploded in Ukraine. It is considered to be the worst nuclear power plant disaster in history as the chain reaction went out of control. 237 people died from acute radiation sickness and 135,000 were evacuated from the area.
• Nuclear energy would be the most dominant source of energy now if it hadn’t been for the Chernobyl and other nuclear disasters.  

Nuclear Warfare:

The discovery of nuclear power has led to nuclear warfare and weapons capable of destroying hundreds of millions of people. The rapidly advancing modern technology means in the future there could be far severe consequences in wars. The detonation of nuclear weapons can have very damaging effects, for example the immediate release of X ray energy, thermal radiation, atmospheric blast and long term radiation.

Development – It began when Antoine Becquerel discovered uranium’s radioactivity. Then Pierre and Marie Curie isolated radium. Einstein then worked out we could transform mass into energy causing huge amounts to be released. Ernest Rutherford and assistants found out about the positive central nucleus and this would release large amounts of energy if it was broken. Nuclear Fission then made it able to split an atom, transforming mass into energy. This soon allowed the creation of the atomic bomb.