ABC-M28A1
Calculator Set
Complete Set
Carry Case
ABC-M1A1 Radiac Calculator
ABC-M4A1 Nuclear Yield Calculator
Instruction & Sample Problem Card
The ABC-M1A1 RADIAC Calculator of the M28A1 Nuclear Calculator Set can be used to determine
the time of entry into a fallout area when the rate of decay is standard (n = 1.2). To determine the
time of entry using the calculator, you must set the known data on the calculator. The dose rate is located
on the outer disc and aligned with the H + 1 hour mark on the intermediate disc.
Locate the total outside dose on the outer disc and note this position in relation to the guide band on the
intermediate disc. Follow this guide band through the intermediate disc and visualize the
relative position where the guide band meets the inner disc. Rotate the inner disc until the stay time fits
between the relative position on the guide band and the time of entry mark. The time on the inner
disc at the time of entry mark represents the time after burst that personnel may enter the fallout area.
Note: This calculator is only accurate for "Standard" decay rates.
Use the nomograms in U.S. Army Field Manual FM 3-12 Chapter 5
for "Non-Standard" decay rates.
Sample Problems For ABC-M1A1
Instructions For ABC-M4A1
ABC-M1A1 Radiac Calculator
To Determine Radiation Dose Rates And Total Dose.
ABC-M1A1 Radiac Calculator Instructions
This is the "back" of the calculator referred to below.
Note: U.S. Army Field Manual FM 3-12 Chapter 5 states:
"The transmission factors used in this manual are preferred
over those on the back of the ABC-M1 calculator."
See transmission factors from FM 3-12 below.
ABC-M4A1 Nuclear Yield Calculator
This side to determine yield from cloud bottom or top
with flash-to-bang time known.
ABC-M4A1 Nuclear Yield Calculator
This side to determine yield from cloud width
with flash-to-bang time known.