Neptunium-237 is a radioactive isotope of the element neptunium, which is part of the actinide series in the periodic table. It has a half-life of about 2.14 million years, making it one of the more stable isotopes of neptunium. Neptunium-237 is produced primarily in nuclear reactors and can be found in spent nuclear fuel. This isotope is significant in the field of nuclear science and waste management. It can be used in research and has potential applications in nuclear batteries and radiological studies. However, due to its radioactivity, it must be handled with care to ensure safety.