text: Due to its high fission yield, relatively long half-life, and mobility in the environment, technetium-99 is one of the more significant components of nuclear waste. Measured in becquerels per amount of spent fuel, it is the dominant producer of radiation in the period from about 10 to 10 years after the creation of the nuclear waste. The next shortest-lived fission product is samarium-151 with a half-life of 90 years, though a number of actinides produced by neutron capture have half-lives in the intermediate range.