Column

(23) Natural nuclear reactorMar 5, 2013

U-235 has a half-life of 0.7 billion years, while U-238 has a longer half-life of 4.5 billion years. So, they are still remaining after 4.6 billion years from the birth of the Earth. It is said that the percentage of U-235 in the natural uranium is 0.72 % and that any planets in the solar system have the same percentage of it. Nuclear power plants use enriched uranium in which the concentration of U-235 is increased to 3~5 % necessary for fission. A Japanese scientist, Kazuo Kuroda predicted that once the Earth had high percentage of U-235, the natural nuclear reactor existed. In 1972, a low percentage of U-235 was discovered at Oklo in Gabon, and the trace of the natural nuclear reactor of 2 billion years ago was revealed. The power of nature such as natural nuclear reactor of the Earth and the nuclear fusion energy of the Sun is beyond human capability.
Related calculator
  • Back