PART A: COMPUTE THE TOTAL DOSE
USING THE TOTAL DOSE (FALLOUT) NOMOGRAM
Total Dose (Fallout) Nomogram.
The Total Dose Nomogram is used for making radiological operational predictions while operating in a
fallout radiation area resulting from a single explosion. This nomogram relates total (outside) dose (D),
dose rate referenced to 1 hour after burst (R1), time of stay (Ts), and time of entry (Te). The index scale
is merely a pivoting point that is used between the D and R1 and the Ts and Te. The four values on this
nomogram are defined as follows:
D = total outside dose in cGy.
R1 = dose rate 1 hour after burst (H+1). When using this nomogram a dose rate
referenced to 1 hour after the burst (H + 1) must ALWAYS be used.
Ts = Time of stay in hours.
Te = Time of entry (hours after burst).
Any one of these values may be determined from the nomogram if the other three values are known.
Determine Total Dose Using the Nomogram.
To determine the total outside dose of radiation to be received by personnel while operating in a fallout
area, you must know the time personnel are to enter the area, how long the personnel will remain in the
area, and what the radiation dose rate is at 1 hour after burst.
Locate the time of entry on the entry time scale and place the end of a hairline on this
mark, holding it in position using a pin or sharp pencil.
Swing the hairline to cross the stay time scale at the point indicating the number of hours
the personnel are to remain in the area.
Move the pin or sharp pencil to secure the hairline in place at the point where it crosses
the index scale. While holding the hairline in place on the index scale, pivot the hairline
to cross the dose rate scale at the point indicating the H + 1 dose rate. The point where
the hairline crosses the total dose scale will indicate the total outside dose of radiation the
personnel will receive while in the fallout area.