Neptunium isotopes are variants of the element Neptunium, which has the atomic number 93. The most common isotopes include Neptunium-237, which is stable and has a half-life of about 2.14 million years, and Neptunium-239, which is radioactive and decays into Plutonium-239. These isotopes are produced in nuclear reactors and during the decay of Uranium. Neptunium isotopes have applications in nuclear science and technology, particularly in the study of nuclear waste and the development of advanced nuclear fuels. Their unique properties make them important for research in nuclear chemistry and radiochemistry, contributing to our understanding of radioactive materials and their behavior.