"Stationary Low-Power Reactor Number One, also known as SL-1 or the Argonne Low Power Reactor (ALPR), was a United States Army experimental nuclear reactor in the western United States at the National Reactor Testing Station (NRTS), later the Idaho National Laboratory, west of Idaho Falls, Idaho. It experienced a steam explosion on the night of January 3, 1961, killing all three of its young military operators, and pinning one of them to the ceiling of the facility with a reactor vessel plug. The event is the only reactor accident in U.S. history that resulted in immediate fatalities.
Personally I'm not worried about the biggest nuclear accident so far. I'm worried about the potential future very unlikely but very severe nuclear accident that kills a non-negligible fraction of the population. An accident that makes Chernobyl look small.
Sure, it's a risk vs reward thing and my comment was just focusing on the risk - a risk that I think is continually downplayed because we are bad at appreciating the costs of extremely unlikely but extremely bad events that have never occurred before.
If the reward is high enough the risk might be justified. Personally I doubt it (mostly because economically solar + wind + power storage seems like a better bet), but that's a whole other discussion.
At best the worst case downside is limited, but so to is the amount of power generated.