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Blast Yield Data: Sources and Treatments

To develop the charts and graphs used to show the effects of above-ground nuclear tests, we combined data from various sources. Some of the data were in different formats and some were presented as a range rather than a numerical reading. Below are descriptions of the differences in data format and sample collection.

Above-Ground Nuclear Blast Yield Data

The following types of nuclear explosions were considered above-ground nuclear blasts:

  • airdrop
  • artillery shell
  • in or above the atmosphere
  • balloon
  • barge
  • open vertical shaft
  • rocket
  • surface (types unknown)
  • tower
  • under water

Data for the annual yield of above-ground nuclear blasts were totaled by country from the Catalog of Nuclear Explosions, compiled by the Oklahoma Geological Survey (July 14, 1998; last accessed May 5, 2002)

If the yield of an explosion was not provided, was listed as a range, or described as low, high, slight, fizz, or blank, we used the following decision rules for summing the data:

Yield Description Assumed Yield in Megatons
High 1.0
Low 0.02
Slight 0.01
Fizzle 0.01
Range The upper limit of the range*
Blank The average yield of tests by the same country in the same year

*The upper limit was used because the mid-point was low relative to other blasts reported for the same country during that year.

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Stronium-90 in Milk Data

We used the nation-wide average of the Sr-90 concentration in milk to measure the effects of above-ground nuclear blasts. We calculated the annual nation-wide average by totaling the available monthly concentrations estimated for each sampling station and dividing by the number of monthly readings available.

Data from 1960-1973 were collected by the U.S. Public Health Service Milk Monitoring Network, which later became part of RadNet's predecessor, ERAMS. During the 1960's, they collected monthly samples and analyzed them for Sr-90. Today, monitors routinely collect quarterly samples, but analyze only the third quarter (July) sample for Sr-90.

Samples are taken from the group of suppliers that provide at least 80% of the milk for a given population center. Individual samples are blended to create a composite sample, which is then analyzed for Sr-90.

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