Information on the half-life of an isotope can be used to calculate how much radioactivity of that isotope will be present after a certain period of time. I-131, used in thyroid scans, has a half-life of 8.02 days. Some isotopes have long half-lives – the half-life of U-234 is 245,000 years. So the half-life of that isotope is one hour.
In one hour, the count could be 15,000 cpm (half the original count). A specific isotope might have a total count of 30,000 cpm. For a radioisotope, every time a decay event occurs, a count is detected on the Geiger counter or other measuring device. The half-life is defined as that period of time needed for one-half of a given quantity of a substance to undergo a change. This loss of activity can be estimated by determining the half-life of an isotope. Radioactive materials lose some of their activity each time a decay event occurs. The 24,100 year half-life means that it will be with us for a very long time. At some storage sites, the waste is slowly leaking into the groundwater and contaminating nearby rivers.
This isotope has a half-life of 24,100 years, causing concern in regions where radioactive plutonium has accumulated and is stored. The plutonium can be used in nuclear weapons and is a power source for nuclear reactors, which generate electricity. Uranium isotopes produce plutonium-239 as a decay product. Calculate half-life when given decay data.
