Just a small point - what has growing air traffic got to do with nuclear power? I don't see any technology here or on the horizon that will let us put anything made by nuclear reactors into the fuel tanks of jet aircraft.

Indeed. If we are aiming to cut carbon emissions in the easiest places first, the order would be

1. Electricity generation
2. Road Transport
3. Aviation

Nuclear and/or renewables would do 1. To achieve 2, we would need plug-in hybrids for partial reductions, and biofuels, or possibly electrically produced hydrogen for complete carbon neutrality. 3 would also require biofuels or hydrogen, the chances of batteries being good enough any time soon are pretty remote.

These things could largely be done today, but are too expensive. The technological challenges involved are those of reducing the costs.

Ah, but do you remember the plan for the 6,000 ton spaceships (genuine Space Ships) powered by nuclear bombs? Now THAT'S what I call science!

If you think I'm joking, check http://en.wikipedia.org/wiki/Project_Orion

Damn that Test Ban Treaty!!!