Neptunium-241 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 56 hours, meaning it takes that long for half of a sample to decay. Neptunium-241 decays into plutonium-241, another isotope that is also radioactive. This isotope is primarily produced in nuclear reactors and can be found in spent nuclear fuel. Due to its radioactive properties, neptunium-241 is of interest in nuclear science and waste management, as it contributes to the long-term radiotoxicity of nuclear waste.