Suggested radius of inner cordoned area

Suggested radius of inner cordoned area (safety perimeter) for a radiological emergency
Situation Initial inner cordoned area (safety perimeter)
Initial determination — outside
Unshielded or damaged potentially dangerous source 30m around
Major spill from a potentially dangerous source 100m around
Fire, explosion or fumes involving a potentially dangerous source 300m radius
Suspected bomb (potential RDD) exploded or unexploded 400m radius or more to protect against an explosion
Initial determination — inside a building
Damage, loss of shielding or spill involving a potentially dangerous source Affected and adjacent areas, (including floors above and below)
Fires or other event involving a potentially dangerous source that can spread materials throughout the building (e.g. through the ventilation system) Entire building and appropriate outside distance as indicated above
Expansion based on radiological monitoring
Ambient dose rate of 100 µSv/h Wherever these levels are measured