Environmental radioactivity part of the Chernobyl release was the caesium-137, this isotope is responsible for much of the long term (at least one year after the fire) external exposure which has occurred at the site. The caesium isotopes in the fallout have had an effect on farming. A large amount of caesium was released during the Goiânia accident where a radioactive source (made for medical use) was stolen and then smashed open during an attempt to convert it into scrap metal. The accident could have been stopped at several stages; first, the last legal owners of the source failed to make arrangements
Isotopes of caesium into solution and is returned to the surface of the earth as a component of radioactive fallout. Once caesium enters the ground water, it is deposited on soil surfaces and removed from the landscape primarily by particle transport. As a result, the input function of these isotopes can be estimated as a function of time. Caesium-131, introduced in 2004 for brachytherapy, has a half-life of 9.7 days and 30.4 keV energy. Caesium-133 is the only stable isotope of caesium. The second is defined by a specific caesium-133 transition. Since 1967, the official definition of a second is 9,192,631,770 cycles of