alarm
alert
atom
atomic
atomic bomb
attention
background
black
black and white
caution
circle
circular
clip art
cold war
contamination
danger
dangerous
deadly
design element
energy
graphic
hazard
hazard symbol
hazardous
icon
illustration
ionizing
isolated
keep out
lethal
nuclear
plain background
power
radiation
radiation sign
radioactive
radioactivity
risk
safety
shape
sign
silhouette
symbol
transparent
warning
white
white background