The  area  marked  Zone  I  is  the  Zone  of  Immediate Operational   Concern.   In   this   area,   exposed, unprotected   personnel   will   receive   the   maximum allowable  emergency  risk  dose  of  150  centi-grays  (rads) of radiation in a time period from 0 to less than 4 hours after  the  arrival  of  fallout.  The  4-hour  figure  is  an estimate of how long it would take to pack up essential ground force military units (equipment and personnel) and evacuate an area as an intact and effective fighting force. Essentially, Zone I must be evacuated before a strike occurs, or the military units in the areas will suffer high  personnel  casualties  and  extensive  loss  of equipment and supplies. The  area  marked  as  Zone  II  is  the  Zone  of Secondary   Hazard.   Exposed,   unprotected   personnel may operate in this area between 4 hours and 24 hours after  the  arrival  of  fallout  before  receiving  150  centi- grays (cGy) of radiation. Essentially, military units in this  area  have  the  necessary  time  to  pack  up  and evacuate  after  the  arrival  of  fallout  and  remain  effective as a fighting force. Outside of Zone I and Zone II, some fallout will be received.  However,  military  units  may  continue operating for up to 24 hours and be expected to receive less than 50 cGy radiation, and to operate for indefinite periods of time without receiving more than 150 cGy radiation. To construct a NATO fallout diagram, follow these steps: 1.  Locate  ground  zero  (GZ)  and  mark  it  on  your chart. 2.  Draw  the  radial  lines.  Using  information  in  a NAV  NBC  3  NUC  or  NBC  3  NUC  message,  draw  a straight line extending from GZ toward the directions indicated  for  the  left  and  right  radial  lines.  These directions   are   measured   clockwise   from   true   north when measurements are in degrees, or clockwise from grid north when measurements are in mils. OR Using information in the TESS RADFO output or an Effective Downwind Forecast, plot a line extending from   GZ   representing   the   Effective   Downwind Direction.  Then,  plot  the  radial  lines  extending  from GZ at 20° or one-half of the expansion angle right and left of the EDD line. 3.   Draw the cloud radius. From the NBC 3 NUC or TESS output, determine the cloud radius. When using an Effective Downwind Forecast, obtain a representa- tive cloud radius for the appropriate yield group from the table provided on the Ship’s Fallout Template (fig. 5-6). Use a compass to set the radius on your chart’s latitude scale (1 minute of latitude is 1 nautical mile) or grid scale, and draw the circle around ground zero. 4.  Draw  the  Zone  I  boundary.  TESS  output:  Set your  compass  to  the  Distance  to  Zone  I  using  the latitude scale. NBC 3 NUC message: Set your compass to  the  Effective  Downwind  Distance,  also  using  the latitude  scale.  Effective  Downwind  Forecast:  Use  the nomogram shown in figure 5-7, the actual weapon yield (or the maximum weapon yield if plotting a yield group for  planning  purposes)  and  the  effective  downwind speed provided by the forecast to calculate the Zone I downwind  distance.  Set  the  compass  to  this  distance. With the compass point at GZ, draw an arc extending between   the   left-   and   right-radial   lines.   Use   a straightedge to draw lines tangent to the cloud radius circle and the point of intersection of the radial lines and the Zone I boundary arc. Label the entire area within the cloud radius circle, the two tangent lines, and the Zone I arc as ZONE I. 5. Draw the Zone II boundary. Double the Zone I downwind distance, and draw a second arc between the radial lines. Label the area enclosed between the radial lines and the Zone I and Zone II boundaries as ZONE II. 6.   Draw  the  fallout  arrival  time  arcs.  The  Effective Downwind Speed is the distance traveled by the fallout in 1 hour. Set your compass to the appropriate distance, place the compass point at GZ, and draw a dashed-line arc over the fallout plot. Label this line as H+1, for the arrival  of  fallout  1  hour  after  detonation.  Double  the distance on the compass and draw a second arc across the diagram. Label the second arc as H+2. Higher yield weapons   may   need   an  H+3  arc.     The  effective downwind speed can also be determined by using the nomogram shown in figure 5-7. 7.   When the effective downwind speed is less than 8 KPH (5 knots), the predicted fallout areas of Zone I and Zone II will be drawn circular around ground zero. 8.   Finally, label the plot with the weapon yield, the date-time  of  the  attack  (or  the  valid  period  of  the Effective   Downwind   Forecast),   the   location coordinates or name of the location, and the effective downwind speed and the UTC time (observation time of the upper winds used in the fallout prediction). The NATO fallout plot (for any scale chart) can also be  constructed  by  using  the  Ship’s  Fallout  Template (fig. 5-6) or the three Land Fallout Templates that come with the ATP-45. The templates are transparent plastic diagrams  with  perforated  holes  used  to  place  guide 5-6