Lesson 2/Learning Event 7
The turn-back dose rate for a ground survey party is calculated as follows:
Rtb = Turn-back dose rate,
OEG = Operation Exposure Guide,
speed = The speed at which the survey party will travel,
distance = The distance the survey party will travel inside the fallout pattern (derived from a
fallout prediction plot if no better information is available).
If the survey party encounters the turn-back dose rate, the party will immediately leave the fallout area
by the same route used to enter it, unless instructed otherwise.
The following is an example of how you would calculate a turn-back dose rate. The commander has
established an Operation Exposure Guide (OEG) of 10 cGy(rad)/hr for a ground survey mission. The
speed at which the survey party will travel is 15 km/hr. The distance the survey party will travel inside
the fallout pattern is 5 km. What is the turn-back dose rate?
Turn-back Dose. The control party (NBCE) also will calculate and provide the turn-back dose for the
survey to the survey party. The turn-back dose is calculated as follows:
where: Dtb = Turn-back dose.