FISSION vs. FUSION

Fission The splitting of a nucleus into smaller fragments when bombarded with neutrons. One large nucleus of a particular isotope breaks into two smaller nuclei of about equal size

U FISSION U neutron neutrons Ba Kr 91 36

Enormous energy – 1 kg of uranium-235 releases an amount of energy equal to that generated in the explosion of 20,000 tons of dynamite If uncontrolled chain reaction, the total energy release is nearly instantaneous – entire reaction takes only a fraction of a second Fission

Atomic bombs are devices that start uncontrolled nuclear chain reactions In controlled settings, like nuclear power plants, the energy is released more slowly – mostly in the form of heat which is absorbed into steam which turns turbines Fission

Access to materials used in fission reactions is somewhat limited Creates radioactive material (a.k.a. – nuclear waste) Fission

Fusion proton neutron ENERGY deuteron 2121 H triton 3131 H

The nuclei combine to produce a nucleus of greater mass The sun uses nuclear fusion of hydrogen atoms into helium atoms Gives off enormous heat and light (and other forms of radiation) Actually more energy than a fission reaction Fusion

Although scientists have been working on controlled fusion reactions, success has not been achieved to any great extent because the temperature required to start a fusion reaction has to be in excess of 40,000,000 °C! Fusion

At these temperatures, matter exists as a plasma (high-energy sate in which ions exist in a gas like form) – to contain plasma that has extreme temperatures, is not possible at this time because no known structural material can withstand the hot, corrosive plasma Fusion

Access to materials for fusion is plentiful Creates less radioactive material than fission – but creates some (nuclear waste) Fusion