Its a full footprint measurement. Coal miner deaths for instance count against it. A study attempted to aggregate fatalities from atmospheric effects from emissions.

It does make nuclear look particularly good, but this is also because it is so energy dense that effort is efficiently allocated. It makes everything except oil and coal look good on a chart.

Most of the deaths attributed to nuclear are more steam plant accidents that also happen in coal plants. Operators are far more likely to die from steam, rotating equipment, or hydraulics than radiation doses. But the energy density of nuclear more efficiently allocates fatalities.

Nuclear power is not dangerous in the same sense that parachuting or commercial flight is not dangerous. You are exposing yourself to lethal forces, but with proper procedures, engineering, and training these activities are safe, even at scale.