How so? A person convinced that any nuclear power plant is a risk of multi megaton explosion would have some very weird ideas of how nuclear power plants should be built; they would deem moderated reactors impractical, negative thermal coefficient of reactivity infeasible, etc (or be simply unaware of the mechanisms that allow to achieve stability), and would build some fast neutron reactor that relies on very rapid control rod movement for it's stability. Meanwhile normal engineering produced nuclear power plants that, imperfect they might be, do not make a crater when they blow up.
To the extent that you already know that nuclear power plants are basically safe they clearly do not apply as an analogy here. Reasoning from them like this is an error.
Another monthly installment of the rationality quotes thread. The usual rules apply: