Hazards and uses of radiation, and nuclear power GapFill

 SituationalBaselineBackgroundSubtractedNaturalEnvironmental radiation is the low-level radiation always present around us. Sources of this radiation can be either  beta sourcesnaturalalpha sourcesgamma sourcesneutron sourcesman-made, such as rocks and cosmic rays, or  man-madebeta sourcesneutron sourcesalpha sourcesgamma sourcesnatural, such as nuclear materials used in medicine, nuclear weapons testing, or nuclear power plant accidents.
A radiation dose is  the amount of radiation an individual is exposed tothe amount of radiation an individual producesthe rate of exposure to radiationthe amount of radiation in a single locationthe amount of radiation detectedthe number of decays from a source, 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  changing hair colournauseafeeling fantasticsunburntumours and cancersuperpowers.
However, radiation can also be very useful; it is used in medicine for  vaccinessurgeryprostheticsultrasound scansgeneral wellnessimaging of internal organs and destruction of unwanted tissues, and in a variety of industrial applications, such as measuring the thickness of metal sheets and detecting gas leaks.
Nuclear power plants use radioactive materials to produce electricity. During  fusionfissionalpha decaybeta decaychemical reactionsgamma decay, 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 exothermica reversiblean endothermica continuousa fasta chain 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.
During  gamma decaychemical reactionsfusionbeta decayalpha decayfission, 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.