The Thorium Series refers to a sequence of radioactive isotopes that begin with the element Thorium-232. This series undergoes a series of decay processes, ultimately leading to the stable isotope Lead-208. The decay involves several intermediate isotopes, including Radium-228 and Actinium-228, each with its own half-life and decay products. Thorium is considered a potential alternative to Uranium in nuclear reactors due to its abundance and the fact that it produces less long-lived radioactive waste. The use of thorium in nuclear energy is being researched as a safer and more sustainable option for future energy needs.