Fallout Calculator 

This java-based interactive calculator shows the distribution of fallout, by wind, from nuclear bomb blasts of various yields. The contours depict calculated radiation doses of 300, 25, and 1 REM at 96 hours after detonation.

In using the calculator, you may select from an assortment of virtual satellite maps of major world cities. You may select the magnitude (15, 30, or 45 miles per hour) and direction of the wind. You may choose from an assortment of yields ranging from 1 kiloton to 50 megatons. And, you may choose the location of the bomb blast on the map simply by clicking on the preferred location.

The calculator requires that you have java installed. It can be found here. [Note: Images may take a little while to load.]

The following dosage information was taken from the Manual of Protective Action Guides and Protective Actions for Nuclear Incidents provided by the United States Environmental Protection Agency.

The contour specifications are as follows:

Blue Ellipse: 300 REM. At this accumulated dosage, the risk of fatalities is approximately 50% and increases drastically closer to the blast site.

Green Ellipse: 25 REM. At this range, only emergency workers and parties fully aware of the associated risks will (on a voluntary basis) be allowed to enter this region for the purpose of saving lives.

Red Ellipse: 1 REM. At this accumulated dosage, evacuation and sheltering is recommended.

In this calculation, we assume a constant "unit-time dose rate" and constant windspeed. We also assume gamma rays to be the primary type of radiation involved, so 1 RAD = 1 REM. Our model is based on a simulation which takes into account the shape of the cloud, radioactive activity for various particle sizes in different regions of the cloud, centerline windspeed effects, a tri-layered atmospheric model, horizontal diffusion, and a detailed accumulated-dose calculation. The Radioactive Cloud Model writeup is available here and a sample Mathcad run of the calculation is available here.  Commentary on the model is encouraged.

The following dosage information was taken from the Manual of Protective Action Guides and Protective Actions for Nuclear Incidents provided by the United States Environmental Protection Agency.

For more information on modern developments concerning nuclear weapons see "Nuclear Weapons in the 21st Century". To send your opinion on nuclear weapons to your representatives in Congress, see the Friends Committee on National Legislation site.

References:

  1. Purnell, Blake. Fallout Model for the Robust Nuclear Earth Penetrator. Federation of American Scientists. Washington, DC, 2005.
  2. Samuel Glasstone and Philip J. Dolan, eds., The Effects of Nuclear Weapons, 3rd ed. (Washington, D.C.: GPO, 1977).
  3. Manual of Protective Action Guides and Protective Actions for Nuclear Incidents. Office of Radiation Programs. United States Environmental Protection Agency. Washington, DC 20460, 1991.