The Beginning of Fission

Enrico Fermi was an Italian physicist that kick started the process of nuclear fission. In 1934 he began bombarding elements with neutrons for a completely unrelated experiment “Fermi and his colleagues bombarded sixty-three stable elements and produced thirty-seven new radioactive ones”. One of the elements being bombarded was the heaviest known element of uranium. What had been produced by this procedure was up for interpretation and many believed the results were “transuranic elements” that were completely new. (Atomic Bombardment, n. d.)

Otto Hahn and Fritz Strassman began research into these findings and concluded that “neutron bombardment of uranium leads to isotopes of radium”. Lise Meitner wrote to Hahn asking for “irrefutable data” that proved this to be true. Upon further tests, Hahn and Strassman found that the decay products were isotopes of barium. The idea of transuranic elements was beginning to fade. With this new research in hand, Meitner and her nephew Otto Frisch used Bohr’s droplet model to “understand how barium nuclei could be formed from uranium nuclei” (Lise Meitner, 2008).

Methods and Technology

Niels Bohr was a Danish physicist that developed a liquid drop model to describe the nature of the nucleus of an atom, “One can visualize the uranium nucleus to be like a liquid drop containing protons and neutrons. When an extra neutron enters, the drop begins to vibrate. If the vibration is violent enough, the drop can break into two pieces. Meitner named this process ‘fission’ because it is similar to the process of cell division in biology” (Nuclear Fission, 2003).

Lise Meitner was able to conduct her own experiments in Sweden thanks to the timely building of their own cyclotron. A cyclotron is a very small particle accelerator that was invented by Ernest Lawrence in 1930. Particle accelerators are devices that produce a beam of charged particles, in the case of Lise Meitner, a uranium atom was used. This particle is propelled through a circular pipe repeatedly to increase the strength of the electric field. A “target” is then put in the particle’s path to produce a collision. (Gerrity, 2014)

Early Cyclotron. © 1998 WGBH

In nuclear fission, the separating of an atom can produce a chain reaction that separates surrounding atoms. This produces a large amount of energy and thus the atomic bomb was born. Meitner refused to work on the atomic bomb despite being asked and it may be one of the worst side effects of her revolutionary research.

Nuclear Fission Today

An atomic bomb is a huge explosion released into the environment, but how to control that energy and use it for in peaceful ways was a bit more challenging. Enrico Fermi created the first nuclear reactor to do just that. It was originally used to research nuclear fission in 1942, but has since been used to build the first nuclear power plants.

These power plants use the energy produced from nuclear fission to heat water boilers. The steam from this process is then utilized to power generators and turbines. There are pros and cons to nuclear power plants and the United States has significantly slowed its construction of these plants. Water vapor is all that is emitted from a nuclear power plant, and although the construction and mining processes used by plants does produce harmful gases, it is much less than coal powered plants. They are however costly to build and the three major nuclear power plant accidents has scared the population. Chernobyl was an enormous accident that killed 50 people and caused the evacuation of thousands.It was also responsible for up to 4000 cases of cancer. The other two accidents were much less severe, but the population is nonetheless still very afraid of the potential harm (What is Nuclear Energy?, 2016).