The spread of Fukushima nuclear radiation in our interconnected world

amazed that particles could be spread across the world from such a small footprint like a reactor, which he compared in size to a swimming pool.

“It shows you how connected the world is,” he said. “What happens in one place can show up someplace else.”

How much Japan radiation? Scientists answer, By PAT BRENNAN / ORANGE COUNTY REGISTER, Aug. 17, 2011 What appears to be the first scientific estimate of radiation released during the height of the Japanese nuclear crisis reveals a burst hundreds of times the background levels near the crippled reactors.

Scientists at UC San Diego did produce a number — a total of 400 neutrons per square meter between Mar. 13 and Mar. 20, some 365 times natural, background radiation levels……

“It’s a large amount of radioactivity, obviously,” said Mark H. Thiemens, dean of the university’s Division of Physical Sciences and an author of the new study.

Perhaps at least as interesting is the way Thiemens, post-doctoral researcher Antra Priyadarshi and their team reached the number: by measuring tiny amounts of stray particles from the crippled Fukushima Daiichi reactors blown on ocean winds across the Pacific and into detectors in La Jolla.

“The fact that we see it across the Pacific Ocean means there was a serious amount of radioactivity at the source,” Thiemens said…….

Many types of particles were produced in the crisis that were later measured on the West Coast, including by a U.S. Environmental Protection Agency detector in Anaheim — all of it in spectacularly tiny quantities that posed no health risk to West Coast residents.

But Thiemens and Priyadarshi focused on the radioactive sulfur. While some of that is produced naturally by cosmic rays in the atmosphere, it cannot reach the quantities seen near the ocean surface during the attempt to cool the Japanese reactors with seawater.

“If they would have put in fresh water, there would be no production of radioactive sulfur,” Priyadarshi said.

By tracing the path of the particles backward and accounting for decay of particles and loss to the ocean, they were able to estimate how big the initial burst of radation was over the troubled reactors, at least in square meters.

Thiemens said he would have to leave it to other scientists to determine how much total radiation was released, or perhaps to refine his team’s calculations.

He said he was amazed that particles could be spread across the world from such a small footprint like a reactor, which he compared in size to a swimming pool.

“It shows you how connected the world is,” he said. “What happens in one place can show up someplace else.”

The study was published online this week in the science journal, Proceedings of the National Academy of Scientists.

http://www.ocregister.com/news/reactors-312426-scientists-thiemens.html