I would point out that the fatalities here only represented 5% of those who would get sick. If only half of the people that got sick required medical intervention/hospitalization, that would be ... bad.
100,000 victims in a blast would be a *severe* crisis. 500,000 - 1,000,000 would incapacitate our health system instantly, and those figures aren't that far out of what one might expect if you were to detonate a low-yield nuke in a city of 10,000,000+
This refers more to a specific detonation of a weapon, and not of an accident, that would be MUCH milder, just to be clear.