Chernobal and Modern Nuclear Power Plants

The Chernobyl disaster was a nuclear accident that occurred on the 26th of April 1986 at the Chernobyl Nuclear Power Plant in Ukraine. An explosion and fire released large quantities of radioactive contamination into the atmosphere, which spread over much of Western USSR and Europe. The Chernobyl disaster is widely considered to have been the worst nuclear power plant accident in history, and is one of only two classified as a level 7 event on the International Nuclear Event Scale. The long term effects of this disaster are still being felt today.

The effects of this disaster include:

- 6000 cases of thyroid cancer in those who were Children or Adolescents at the time of the disaster.

- Four square kilometres of pine forest near the reactor died.

- Ban of all wild game meat in Germany, even to this very day, because of the nuclear contamination found in hunted animals still being over safe levels for human consumption.

- Death of thousands of animals within the immediate area of the Power Plant.

- World-wide the numbers of cancer deaths attributed to the disaster numbers around 27,000

- Total numbers of additional deaths attributed to the disaster where number by one report commissioned by Greenpeace is around 200,000 worldwide. Most of the study's sources are from peer-reviewed journals, including many Western medical journals, or from proceedings of scientific conferences

The cause of all these effects is, of course, Radiation. The three main types of nuclear radiation - alpha radiation, beta radiation and gamma radiation all played a big part in the disastrous after effects of the Chernobyl disaster.

Alpha Radiation

Alpha particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus. Due to the mechanism of their production in alpha radioactive decay, alpha particles have a kinetic energy of about 5 MeV (Megaelectron Volt), and a velocity in the vicinity of 5% the speed of light. They are a highly ionizing form of particle radiation, and have low penetration depth. They are able to be stopped by a few centimetres of air, or by the skin.

When alpha particle emitting isotopes are ingested, they are far more dangerous than their half-life or decay rate would suggest, due to the high relative biological effectiveness of alpha radiation to cause biological damage, after alpha-emitting radioisotopes enter living cells. Ingested alpha emitter radioisotopes are an average of about 20 times more dangerous, and in some experiments up to 1000 times more dangerous, than an equivalent activity of beta emitting or gamma emitting radioisotopes. So when the this sort of radiation is ingested into the human body and travels down the patients throat this radiation blasts areas like the Thyroid with mass amounts of this deadly ionising radiation. This is what is thought to be the cause of almost 99% of cases of thyroid cancer in people exposed to the Chernobyl radiation. This radiation is also thought to be causing of another 83% of all other cancer cases in patients exposed to Chernobyl radiation.

Alpha Decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle (two protons and two neutrons) and decays into an atom with a mass number 4 less and atomic number 2 less. E.g.:

238U → 234Th + α

Alpha decay typically occurs in the heaviest elements. In theory it can occur only in nuclei somewhat heavier than nickel (element 28). In practice, this mode of decay has only been observed in nuclides considerably heavier than nickel, with the lightest known alpha emitter being the lightest isotopes of tellurium (element 52).

Beta Radiation

Beta particles are high speed, high energy elections which are emitted by certain types of radioactive elements such as potassium-40. Beta particles are assigned the Greek letter beta (β). There are two types of beta decay β + and β - . Unstable nuclei with an excess of protons may undergo β + decay where a proton is converted into a neutron, a positron and a neutrino. While unstable nuclei with an excess of neutrons undergo β - decay where are neutron is converted into a proton, an electron and an antineutrino (the antiparticle of the neutrino). Typically beta particles have energy levels around 1 MeV and are ultrarelativistic, this means that they have speeds very, very close to the speed of light.

Beta particles are faster than Alpha particles and so penetrate further. A beta particle will be halted by an Aluminium plate, while an alpha particle will be halted by a piece of paper. Beta particles are also strongly ionising, 1 beta particle will cause 100 ionisations. These particles are believed to make up about 16% of the total cancer cases in those exposed to Chernobyl radiation, because while beta particles are penetrate more and are more ionising than alpha particles, alpha particles made up a much higher percentage of the radiation released by the Chernobyl incident. Beta particles do however account for the largest amount of damage caused to the flora and fauna of Europe by the radiation released during the disaster.

Gamma Radiation

Gamma radiation is electromagnetic radiation of high energy, Gamma-rays, like alpha and beta particles, are ionising radiation and so are hazardous to human life. Gamma-rays have energy levels of about 100 KeV (Kiloelectro Volts) and have wavelengths of about 10 picometres

Gamma rays are very poor at ionising, about 1 ionisation to 1 particle but they are very difficult to stop (they are very penetrating). As they are not good ionisers, they are less dangerous to life. They are in fact pure energy (at the shortest wavelength end of the E-M spectrum) and gamma emission accompanies most emissions of beta or alpha particles. Due to their low penetration and low ionising capabilities, Gamma-rays have been thought to only account for 1% of the after effects of the Chernobyl incident.

Cloud of Radiation

The cloud of radiation that moved over Europe as a result of the reactor explosion drifted over Russia, Belarus, Ukraine, Turkey, Greece, Moldova, Romania, Bulgaria, Lithuania, Finland, Denmark, Norway, Sweden, Austria, Hungary, Czechoslovakia, Yugoslavia, Poland, Estonia, Switzerland, Germany, Italy, Ireland, France, Corsica, Canada and the UK. This cloud of radiation caused contamination in an irregular pattern around Europe due to weather patterns.

Within this cloud of radioactive material was about 150 metric tons of particulized and vaporized Uranium, around 85% of the total amount of