The cause for such a small tiny risk in Nuclear is the fact that it is by far the most dangerous thing in the world. We all remember what happened with Japan when they had an earthquake so big that the nuclear plant had a leak and that caused so much problems for them. It means normally 99.99999% of the time it is by far the safest since if you do not secure it good enough then we are talking about generations of cancer and other bad stuff going around in that place, hence anyone who does it does it very carefully. Wind and Solar and Hydro is by far still the best and most efficient way since it neither hurts the world nor that difficult to do neither, such an easy way to handle.