Iodine-131 (or I-131) is a radioactive substance that emits both beta and gamma radiation and has a half-life of 8.03 days. Under normal circumstances, there are low levels of I-131 present in the ...

During nuclear fission – the process used in nuclear plants and bombs – radioactive isotopes of uranium and plutonium decay to form dozens of elements, some radioactive and some not. One is iodine-131 ...

Iodine-131: Used to treat thyroid gland (in the neck). ... This means that the beta-decay emissions can be monitored and the data used to calculate how long it has been since the material was alive.