But a regular explosion containing radioactive materials could still have fallout
This could have been a dirty bomb
Or, it could have been shoddy construction, poor maintenance and lax oversight of the physical plant and the resulting fire and explosion released something that was being shipped.
BTW: People in China I know are telling me the death toll is closer to 500 than the 50 that is being reported.
Would not be surprised. Know MD who worked on Chernobyl victims. Could be as many as 81,000 fatalities over the 3 to 8 generations it will take to eliminate the structural cell damage in offspring of children who were in Pripyat, Chernobyl Oblast (county), Gomel Oblast and surrounding areas.