Final answer:
Nuclear energy produces radioactive isotopes as one of its environmental waste products, which are high-level waste and include isotopes like plutonium-239 that require careful management to avoid contamination.
Step-by-step explanation:
One of the environmental waste products of nuclear energy is radioactive isotopes. When nuclear reactions occur, they produce various radioactive materials. These radioactive materials can include isotopes such as plutonium-239, which is a form of high-level radioactive waste that needs to be carefully managed to avoid environmental contamination. High-level radioactive waste consists of used nuclear reactor fuel, which is solid and must be stored safely to protect the environment and human health. Although nuclear energy does not produce greenhouse gases directly during electricity generation, management of its waste is a significant environmental concern.