Fusion
The resulting radiation is a fraction of what you get from existing nuclear plants, all you need is the technology to contain the reaction and a supply of deuterium. As it happens, there is a lot of it on the moon, which is why Russia, India, the US, Japan and the EU are working towards a permanent manned presence there within the next thirty years or so.
(Bicycle Repairman "you're also a bit of a wanker", Mon 22 Jun 2009, 11:13, Reply)