The danger of fuel is that the fuel that nuclear fission power plants uses is Uranium and its limited to a few suppliers and countries. For example India had to shut down their nuclear plants because of embargoes. The nuclear fuel could be very high radioactive and needs to be handle with great care. There is no Foolproof way to dispose nuclear waste fuel after it is used in the nuclear reactors. Waste is mainly stored at individual reactor sites and there are over 429 locations around the world where radioactive material continues to accumulate.

http://topics.nytimes.com/top/news/business/energy-environment/atomic-energy/index.html

http://www.world-nuclear.org/uploadedImages/org/info/Nuclear_Fuel_Cycle.png?n=7249