On April 27, 1953, at the Rensselaer Polytechnic Institute in Troy, New York, Professor Herbert Clark and his students entered a metal shack that served as a laboratory for their radiochemistry class. All the Geiger counters were registering radiation many times the normal rate. The students carried the radiation measuring devices to areas on campus noting the high readings. Assuming the previous night's heavy rains had washed some atmospheric radiation onto the campus, Dr. Clark contacted John Harley, an associate at the U.S. Atomic Energy Commission's Health and Safety office in New York City. Dr. Clark summarized the details of campus measurements from his class. Gamma radiation on the ground was ten to five hundred times normal; beta ray radiation was even higher and hot spots of even high readings were found in rainspouts and puddles.
Later that day, Dr. Clark learned there had been an atomic bomb test conducted by the AEC in the Nevada desert two days earlier. The mushroom cloud had reached 40,000 feet into the atmosphere then drifted 2,300 miles across the United States in a northeasterly direction. It passed over Utah, Colorado, Kansas, Missouri, Illinois, Indiana, Ohio and Pennsylvania before being caught up in a storm that dropped rain on upstate New York, southern Vermont and parts of Massachusetts.
Dr. Clark's students took their geiger counters on the road and began measuring the radioactivity on the ground, roof shingles and vegetation wherever they stopped in Albany, Saratoga Springs, and Schenectady, New York. Typical readings were twenty to one hundred times higher than normal. This has become known as "the Troy incident."
Surprisingly, they found that it was comparable to that reported the previous year by the AEC’s New York Laboratory for fallout in desert areas only 200 to 500 miles from the point of detonation at the Nevada test site itself.
Interesting and good catch.
The difference between atomic bomb testing and Fukushima Daiichi is Fukushima Daiichi did not punch a bunch of radiation into the upper atmosphere - it’s not up there to come down in the form of rain.