• Jonna Vejrup Carlsen

Thorium (Th90)

Updated: Sep 10, 2020

In 1900 thorium was used in street lamps, as the metal had a long life, but is was as early as in 1828 that the Norwegian priest Hans Morten Thrane Esmark in the Southern part of Norway found the stone looking like silvery metal. He sent the stone to the Swedish chemist Jöns Jakob Berzelius, who discovered a slightly radioactive element and gave it the name thorium after the Nordic god Thor (the god of lightning).

In 1942 during WWII the American physicist Alvin M. Weinberg (1915-2006) saw the potential of thorium and joined a group researching in nuclear physics - with uranium and thorium. Some from the group a.o. Niels Bohr developed the nuclear bomb (with uranium), which helped to end WWII, and in the years 1955-1973 Weinberg being the leader of Oak Ridge Laboratories in Tennessee developed a nuclear reactor with thorium. Thorium does not have the same waste problems as uranium, as it can be used almost 100% (uranium about 2%). However, it was during the time of the cold war, and in 1973 President Nixon decided that despite the good results the thorium research should stop. President Nixon preferred uranium which could also be used for making bombs - which was not possible with thorium.

Alvin Weinberg and other scientists were concerned about the air pollution from the large consumption of fossil fuels and were afraid of a resultant global warming. In 1975 he wrote an article in the Science Journal: Global Effects of Man's Production of Energy! He warned about the consequences for the climate, but not many listened. Now we are facing the problem!

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