Chapter II - Domestic CBRN CM (5) Unique Planning Considerations in the Domestic Operational Environment: (E) Control Zones: (4) Zone Control in Nuclear Detonations: DHS has worked with partner agencies and emergency response partners to establish standard guidance for emergency planners with nuclear detonation specific response recommendations to maximize the preservation of life in the event of an urban nuclear detonation. The planning guidance summarizes recommendations based on the effects of a 10 KT nuclear detonation in an urban environment. The nuclear explosions observable phenomena, in the area around ground zero, are linked to an accumulation of the hazards from pressure (blast), heat (thermal), and radiation as discussed in Chapter I, Overview. These cumulative hazards make it more dangerous for rescue workers and less likely to find survivors the closer one moves toward the point of detonation. The observable phenomenon of damage to infrastructure and other objects provides a way to describe zones with rough approximation delineations that can assist planners and the initial emergency responders in managing risk before radiation levels have been measured and hazard areas marked. There are no clear boundaries between damage zones resulting from a nuclear detonation, but generally, the light damage zone is characterized by broken windows and easily managed injuries; the moderate damage zone by significant building damage, rubble, downed utility poles, overturned automobiles, fires, and serious injuries; and the severe damage zone by destroyed infrastructure