It is impossible to ensure that any underground storage site will be safe for such a long period of time. As well, after 35 years or so, the entire nuclear power plant must be decommissioned at a very high financial and environmental cost, with millions of tons of concrete and pipe having to be buried. Oil burns cleaner than coal, but still produces large quantities of pollution per unit of energy produced. With most of the oil in the U.S. already extracted, future dependence on oil would require an increase in imports. Increased reliance on oil imports would be unwise economically and politically.
Natural gas is inexpensive and environmentally benign.
These two factors have greatly increased the use of natural gas to generate electricity. Natural gas does produce air pollution, but not nearly as much as other fossil fuels. Although natural gas reserves will last for many decades to come, they are finite and, with scarcity, their price will rise. Many of these sources of energy would not be economically competitive if we were to pay their full costs, including damage to the environment and human health, and long-term storage costs. Society bears these costs and are not reflected in our energy bills.