Although this seems like a general curiosity question, rather than a work-related issue, I will try to answer it, at least to some degree.
All currently running nuclear plants use the same process - nuclear fission - to generate electricity. The majority of these plants use uranium, although there are a few which use plutonium. The process involves "splitting" the uranium/plutonium atom by striking it with a neutron. The split atom then creates new atoms, some of which are radioactive, some of which aren't. The radioactive ones are called isotopes.
There are charts in various nuclear texts, and probably also on the Internet, which give the probability of a uranium atom splitting into certain isotopes, and the resultant half-lives. Some are very short lived, others very long. Although the probability of certain isotopes changes with plutonium being used, the actual types of isotopes remains the same. There’s a fairly good article on Wikipedia. For this type of question, it is a much better source.
Patricia Lougheed
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