To get a better average you'd need to compute the total radioactive emissions of all nuclear plants divided by their operating time and compute per GWh versus c

To get a better average you'd need to compute the total radioactive emissions of all nuclear plants divided by their operating time and compute per GWh versus coal plants on the same scale. Chernobyl and Fukushima are two exceptional events. There are hundreds of reactors out there both civilian and military that have never had catastrophic faults.