Plutonium-238

Plutonium-238 (Pu-238) is an isotope of plutonium, which is a heavy and radioactive metallic element. It has a half-life of about 87.7 years, making it relatively short-lived compared to some other isotopes of plutonium. Pu-238 is primarily used as a heat source in radioisotope thermoelectric generators (RTGs) — devices that convert the heat released by the decay of radioactive material into electrical energy.