Radiation
http://www.alternatewars.com/WW3/WW3_Documents/US_DOE/LAMS-2550/LAMS-2550_SL-1_Autopsy.pdf

https://www.youtube.com/results?search_query=wood+river+junction+criticality

25rad:lowest dose to cause clinically observable blood changes
200rad:local dose for onset of erythema in humans
400rad:whole body LD50 for acute radiation syndrome in humans
1krad:whole body LD100 for acute radiation syndrome in humans[7]
1 to 20krad:typical radiation tolerance of ordinary microchips
4 to 8krad:typical radiotherapy dose, locally applied
10krad:fatal whole-body dose in 1964 Wood River Junction criticality accident[8]
1Mrad:typical tolerance of radiation-hardened microchips