Imagine the following game: you throw three dices. If the three dices are not ending on 1, you win 1 dollar. If they are ending on three 1, you lose 100'000 dollars.
If you throw the dice ten times, you will, with high probability, not have three 1 (the probability of appearing is 0.5% per throw). You will probably need to throw more then 10 times before loosing. But when loosing, you will lose a lot too, which makes the bet intrinsically a bad idea (the win does not justify the risk if unlucky).
France has 56 nuclear plants. 56! It's totally unreasonnable to draw conclusion on intrinsic safety of the nuclear plants on such a small number. The fact that you cover the full population with a small number of plants does not change that: it does not change the fact that you cannot conclude scientifically. The same way it is incorrect to say "I only need 3 throws, so it means that the 1-1-1 bet is intrinsically a good idea".
(PS: please do not answer about "loosing 100'000 dollars, but with nuclear disaster, it's not that bad", it's not the point. The point is that statistics is a large number game, and that we just don't have a large number of nuclear power plants to do statistics with them)