Environmental isotopes isotope. For example, H (tritium) is a radioactive isotope of hydrogen. It decays into He with a half-life of ~12.3 years. By comparison, stable isotopes are more stable, decaying much more slowly and having much longer half-lives. Examples of stable isotopes are Sr and Sr. These isotopes of strontium have half-lives on the order of billions of years or are unmeasured because of how stable they are. On timescales that geologists and environmental scientists investigate, these isotopes are stable. Both of these types of isotopes are useful to scientists. Radioactive isotopes are generally more useful on shorter timescales, such as
High-level radioactive waste management involving permanent storage, disposal or transformation of the waste into a non-toxic form. Radioactive decay follows the half-life rule, which means that the rate of decay is inversely proportional to the duration of decay. In other words, the radiation from a long-lived isotope like iodine-129 will be much less intense than that of short-lived isotope like iodine-131. Governments around the world are considering a range of waste management and disposal options, usually involving deep-geologic placement, although there has been limited progress toward implementing long-term waste management solutions. This is partly because the timeframes in question when dealing with radioactive waste