Hazards and uses of radiation, and nuclear power GapFill

 EnvironmentalNaturalBackgroundBaseline radiation is the low-level radiation always present around us. Sources of this radiation can be either  beta sourcesman-madenaturalalpha sources, such as rocks and cosmic rays, or  naturalbeta sourcesman-madealpha sources, such as nuclear materials used in medicine, nuclear weapons testing, or nuclear power plant accidents.
A radiation dose is  the amount of radiation in a single locationthe rate of exposure to radiationthe number of decays from a sourcethe amount of radiation an individual is exposed to, and it is very important to keep annual dosage below a maximum. If this maximum dosage is exceeded, people can get very sick – short-term effects of radiation are called radiation sickness, and long-term effects could include  sunburntumours and cancernauseasuperpowers.

However, radiation can also be very useful; it is used in medicine for  imaging of internal organs and destruction of unwanted tissuesprostheticssurgerygeneral wellness, and in a variety of industrial applications, such as measuring the thickness of metal sheets, detecting gas leaks, and killing harmful or unwanted organisms by irradiating food to prolong its shelf life or by  cleaningdisinfectingsterilisingheating up medical equipment. Nuclear power plants use radioactive materials to produce electricity.

Care must be taken when working with radioactive materials. Radioactive sources should be kept in  safetyshieldedreflectivevery thick-walled containers, and handlers should wear  personal protective equipment (PPE)a helmet with a visora mask and glovesspecial clothing and keep exposure to the minimum. Often,  shopkeepersdoctorscouncil workersradiographers, scientists, nuclear power station workers and other people in danger of irradiation will wear a dosemeter to measure their exposure.  ImpurityPoisoningPollutionContamination by a radioactive substance is where a radioactive isotope gets into another material in error, whereas  irradiationelectromagnetic radiationilluminationirritation is where a material, or person, is exposed to alpha, beta, gamma or other harmful radiation.

During  beta decayfissionalpha decayfusion, a large nucleus, such as uranium or plutonium, absorbs a neutron and splits into two smaller nuclei, and several more neutrons are emitted – this releases energy. The neutrons emitted can be absorbed by further nuclei, causing them to split; if this continues to happen,  an endothermica fasta chainan exothermic reaction occurs. In a nuclear reactor, this reaction is carefully controlled to maintain a constant rate of reaction and heat produced; however, in an atomic bomb, this reaction is uncontrolled.

In a fission reactor, the rate of reaction is controlled by inserting boron or cadmium  rodsmaterialcontrollerssticks into the reactor to absorb neutrons and to limit the chain reaction.

During  beta decayalpha decayfissionfusion, two light nuclei join together to create a heavier nucleus – this releases more energy than a nucleus splitting, but is very difficult to achieve, requiring very high temperatures and pressures.