Chernobyl disaster to residual radioactivity from Chernobyl in the plants they graze on in the wild during the summer. 1,914 sheep needed to be given uncontaminated feed for a period of time before slaughter during 2012, and these sheep were located in just 18 of Norway's municipalities, a decrease of 17 from the 35 municipalities affected animals were located in during 2011 (117 municipalities were affected during 1986). The after-effects of Chernobyl were expected to be seen for a further 100 years, although the severity of the effects would decline over that period. Scientists report this is due to radioactive caesium-137 isotopes
Isotopes of caesium not produced by nuclear weapons because Cs is created by beta decay of original fission products only long after the nuclear explosion is over. Cs also captures neutrons with a cross section of 13.00 barns, becoming medium-lived radioactive Cs. Caesium-136 undergoes beta decay (β−), producing Ba-136 directly. Caesium-137, with a half-life of 30.17 years, is one of the two principal medium-lived fission products, along with Sr, which are responsible for most of the radioactivity of spent nuclear fuel after several years of cooling, up to several hundred years after use. It constitutes most of the radioactivity still left from the