[pfdietz]

You can ask what CO2 tax would be needed to make a particular non-fossil source feasible.

For nuclear in the US, CO2 taxes would have to be $300-400/ton for nuclear to compete with natural gas combined cycle. This number is from the president of Exelon, which operates 20 or so power reactors in the US. Exelon has given up even planning for new nuclear power plants; they are too far out of the running.

[eloff]

I think it should be set at the first to sequester a ton of CO2. Which would be in that neighborhood.

You can't do that overnight, that'd be a huge shock to the economy. But you can implement it over ten to twenty years, ramping it up gradually.