Nuclear energy is a clean energy source, but its byproduct is toxic nuclear waste. Currently, all nuclear waste is disposed of in repositories within the Earth. These facilities are not permanent, and there is a potential risk of leakage in the future due to calamities like earthquakes.

• Per cubic foot: This depends on the type of waste (short-lived vs long-lived isotopes) and can range from $140 to $320 per cubic foot.
• Total repository costs: The US Department of Energy estimates the total cost for a permanent disposal facility like Yucca Mountain to be between $21 billion and $37 billion. This includes construction, operation, and long-term maintenance.