• Kyodo


The atomic bomb dropped on Hiroshima in 1945 was slightly more powerful than had been thought, according to a recent study by experts in Japan and the United States.

The “yield” of the bomb was actually equivalent to 16,000 tons of TNT, rather than the previously thought 15,000 tons, according to the experts, who will be making a presentation on the subject at a meeting of Japanese and U.S. researchers in California this week.

One of them, Masaharu Hoshi, a physics professor at Hiroshima University, said Japanese and U.S. scholars last year revised the estimated altitude where the bomb exploded over the city to 600 meters from 580 meters.

They then came up with a new formula for computation that would wipe out discrepancies between estimates of radiation doses and actually reported doses, he said.

The U.S. scholars then proposed that it may be necessary to revise the amount of atomic fission, which measures the force of explosion, so that those estimates and the actual doses match.

The scholars from the two countries have since been working on this issue, Hoshi said, noting that the latest revision of the yield is unlikely to result in changes to the estimated amount of radiation to which people were exposed.

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