Until such time that a viable nuclear fusion process is perfected, the significant problem of waste material disposal will limit the use of the current fission technology. At this time, here in the U.S., a proposed nuclear waste disposal site at Yucca Mountain in Nevada has been proposed, partially built but still faces scientific criticism, since the half life of the radioactive waste reaches thousands of years. It's nearly impossible, as boobesque and rojash cite, to predict what can occur to such a disposal site for those time spans, yet it's absolutely neccessary to protect the future generations. As opposed to fission, the main distinction is that fusion power produces no high-level radioactive waste. I think it's entirely probable that large scale solar power cells may be developed before reaching a viable solution with fusion power... in my opinion...