Nuclear waste won't kill anyone, as long as it is contained in the storage containers. We just don't have found a way to keep it guaranteed safe for centuries.
Solar alone could easily power the country. Covering large parts of Arizona would produce enough energy to power the whole world. Powering the US, especially distributing it across the states, makes that an easy job. And of course, there is wind. Probably it would be enough to cover all rooftops to power any state.
On Sunny days, Germany can power 30% of the grid by solar only, and that is in a country which is less suitable for solar than any place in the US except Oregon.