80 Years Nuclear Fission: The Fact Check for the Anniversary

Exactly 80 years ago, on December 17, 1938, Otto Hahn, Fritz Strassmann and Lise Meitner discovered the nuclear fission. Their discovery revolutionized engineering and physics.

You can see the Grohnde nuclear power plant near Hameln in Lower Saxony.

The Grohnde nuclear power plant near Hameln in Lower Saxony is expected to be shut down by the end of 2021.

Photo: Panthermedia.net/ ThorstenSchier

On 17 December 1938 – 80 years ago – Otto Hahn, Fritz Straßmann and Lise Meitner discovered the nuclear fission. They bombarded uranium with slowed down, thermal neutrons and were able to detect barium as a fissile product by wet-chemical means. A short time later they identified krypton or xenon as further fission products.

First indications of enormous amounts of energy

Hahn’s and Straßmann’s aim was actually to produce heavy elements, so-called transurans. But the experimental data confused everyone involved. Hahn reported Meitner, who was then in Sweden, of experimental results. The physicist answered: “It seems to me that the assumption of such a widespread bursting is very difficult, but we have experienced so many surprises in nuclear physics that it is impossible to say that it is impossible.” With her nephew Otto Frisch, a pupil of Niels Bohr, they made theoretical reflections. If it had actually come to a nuclear fission, so would have originated a huge energy of 200 MeV. Their results appeared on February 11, 1939 in Nature.

From Nuclear Fission to Chain Reaction

The paper acted as a spark for several research groups. Niels Bohr found that uranium-235 is split in the experiment – not uranium-238, as postulated by Hahn. Later, Frédéric Joliot realized that 2 to 3 neutrons are produced per splitting process. He postulated the theoretical possibility of a chain reaction. Siegfried Flügge came up with the idea of ​​technically exploiting uranium splits.

The first experimental reactor is created

Frisch and Meitner also exchanged information with Bohr. The Danish physicist traveled to the USA on January 16, 1939. He met Albert Einstein and discussed with him all topics related to nuclear fission. Einstein’s special theory of relativity, formulated in 1905, linked energy and mass differences. Enrico Fermi recognized the potential. From 1942 he built in a former football stadium, the first functional nuclear reactor “Chicago Pile 1”. Further experimental reactors followed. German researchers led by Werner Heisenberg and Carl Friedrich von Weizsäcker did not succeed in developing a functioning nuclear reactor until the end of the war.

Towards the Atomic Bomb

Towards the end of World War II US military suspected Nuclear fission could also be suitable as a “miracle weapon”. General Leslie R. Groves led the Manhattan Project. Its goal was to build a functional atomic bomb. As a scientist Robert Oppenheimer was one of the party. On July 16, 1945, researchers showed in the Trinity test that their theoretical considerations were correct. The bomb with plutonium as fuel had an explosive force of 21 kilotons of TNT. At the time, the Allies were close to victory, only Japan refused to capitulate. Thus, Japan stood firm as a strategic goal. The two fires over Hiroshima (August 6, 1945) and Nagasaki (August 9, 1945) claimed a total of up to 300,000 lives.

Peacetime Energy

After the Second World War, more nuclear weapons were developed. At the same time, engineers continued to develop nuclear reactors for peaceful energy generation. End of 1951 produced a test reactor in the US state of Idaho for the first time electricity. The first power plant for large-scale energy production was 1954 Obninsk near Moscow. In 1955 Calder Hall followed in the UK. In Germany, the peaceful use of nuclear energy began in Germany in 1961 at the Kahl nuclear power plant.

The other side of the coin

For years, nuclear energy has been regarded as a pioneering technology. Several oil crises and rising coal prices made new ways of generating electricity necessary from the 1960s. On April 26, 1986, the nuclear catastrophe in Chernobyl showed the downside of peaceful use. After experiments on a reactor block, there was an explosion and release of nuclides with the total activity of several trillion Becquerel. Almost exactly 25 years later, from 11 March 2011, the Japanese nuclear power plant Fukushima Daiichi crashed. There are different opinions about the dose released – the values ​​range from 40 to 100% compared to Chernobyl.

Change of direction in Berlin

On March 14, 2011 – a few days After the start of the nuclear disaster in Fukushima, Merkel decided to radically change its current energy policy. Runtime extensions for nuclear power plants have been withdrawn and phased phasing out is expected by 2022.

admin