SAN DIEGO, Aug. 15 (UPI) -- Researchers have reported the first quantitative measurement of radiation released from the damaged nuclear reactor in Fukushima, Japan, earlier this year.
Atmospheric chemists at the University of California, San Diego, say their estimate is based on air sampling that detected a signal of radiation all the way across the Pacific from the reactor damaged in the March earthquake and tsunami.
Fifteen days after Fukushima operators began pumping seawater into damaged reactors to cool them, a spike in levels of radioactive sulfur from the resulting steam vented into the atmosphere from the plant was recorded by UCSD researcher Mark Thiemens, a university release reported Monday.
Thiemens and his colleagues calculated that 400 billion neutrons were released per square yard of the cooling pools surfaces between March 13, when the seawater pumping operation began, and March 20.
Concentrations a half-mile or so above the ocean near Fukushima must have been about 365 times higher than natural levels to account for the levels they observed in California, the researchers said.
"In any disaster, there's always a lot to be learned by analysis of what happened," Thiemens said. "We were able to say how many neutrons were leaking out of that core when it was exposed."