Rotate the hairline to cross the dose rate scale at the mark representing the H + 1 dose
rate in the fallout area.
Move the pin or sharp pencil to hold the hairline in position at the point where the
hairline crosses the index scale. Rotate the hairline to cross the stay time scale at the
point representing the number of hours personnel will remain inside the fallout area.
Read the value at the point where the hairline crosses the entry time scale. This value
represents the time-after-burst that personnel can enter the fallout area.
EXAMPLE PROBLEM: A commander must send personnel into a fallout area. The personnel will be
in M113 Armored Personnel Carriers (TF 0.3) and are not to receive more than 30 cGy of radiation.
The mission will take approximately 2 hours to complete. The H + 1 dose rate is 150 cGyph. What is
the earliest time personnel can enter the area?
R1 = 150 cGyph
= 30 cGy
= 0. 3
H + 1.6 (Figure 3-1)