1) We already have a new generation of newer safer nuclear plants. They just aren't being built in the US.
2) You actually can't make nuclear plants much more efficient--if by that you mean in terms of energy produced per unit of input. The "inefficiency" of nukes cited by environmentalists has to do with the cost / KwH. That cost reflects enormous legal and licensing costs caused by--guess who--environmentalists. It's like the people who argue that capital punishment is cruel because death row inmates are strung out for 10-15 years while neglecting to mention that they're the very people funding the appeals.
Bless you for being here and pushing back the frontiers of blissful ignorance!!!
Here is an interesting design:
http://www.ga.com/gtmhr/