We don't need better nuclear power tech, we need uniformly good design of anything as potentially catastrophic as nuclear power.
Take the best tech in the world, and have it implemented in shitty design, and we get exactly what we've already gotten.
The nuclear accidents that we have had were exclusively the result of poor design/implementation.
Read "The Design of Everyday Things" if this interests you.
EDIT I made the previous statement based on the feasability of "zero waste nuclear" tho this could be bullshit, and if it is bullshit, then the 1/4 million year *half* life of waste poses a potentially planet killing challenge