The risks associated with nuclear can be mitigated by careful siting of power plants and by not cutting corners in construction. There are safety considerations too in the mining and transport of materials. To a considerable degree we can addresss these risks. The main risk from fossil fuels, the emission of carbon dioxide, is a factor that we have, as yet, failed to address. And, in terms of the threat to all of us, it's far and away more deadly than the risks associated with nuclear power. But there's no such thing as a free lunch.