Radiation Dosage Calculator (early 1950s)

The Radiation Dosage Calculator was developed in 1950 or 1951 by William Orr at the University of Connecticut for the Connecticut State Office of Civil Defense. They were sold to the general public for one dollar each. The design is essentially the same as that of a calculator developed by H. F. Hunter. 

Radiation Dosage Calculator (early 1950s)

If the exposure rate (rads/hr) is known at a given time after an explosion, the calculator predicts the exposure rate at any other time. It also estimates the dose to personnel who are in the area at specified periods of time after the explosion. The back of the slide rule has the instructions.

The assumption is that the exposure rates decrease according to t-1.2 where t is the time in days after the explosion. For what its worth, -1.2 is the slope of the Way-Wigner curve described in the paper "The Rate of Decay of Fission Products." The photo to the right shows a portion of an autographed copy of the paper that is in the ORAU collection.

The U.S. Army employs a military version of this calculator: the ABC-M1A1.

Radiation Dosage Calculator (early 1950s)

Size: 4.5" diameter


  • William Orr. Dosage Calculator. Nucleonics, November 1951, pages: C-10 - C-11.
  • Directions for Using the Radiation Dosage Calculator. No date.
  • H. F. Hunter. NRDL Report AD-234 (H). I have not seen this and any help in locating a copy would be appreciated.