Global nuclear bomb sensors used to track Japan's radiation

Published 28 March 2011

A worldwide network of radiation sensors originally built to detect nuclear weapon tests is now being used by scientists to track radiation leaked from Japan’s Fukushima Daiichi nuclear power plant; over 280 sensors were installed to detect radiation from nuclear weapons testing; the sensors have detected several radioactive elements that are the byproducts of nuclear fission like iodine-131 and cesium-137 from Japan; experts studying the data disagree on the effect and size of the release, but assure the public that the effects are minimal as much of the radiation is being scattered across the Pacific

A worldwide network of radiation sensors originally built to detect nuclear weapon tests is now being used by scientists to track radiation leaked from Japans’ Fukushima Daiichi nuclear power plant.

As part of the Comprehensive Test Ban Treaty (CTBT), radiation sensors were built across the world about ten years ago to enforce a bans on nuclear weapon testing.

 

“We have currently over 280 sensors worldwide, monitoring underground, the atmosphere, the oceans for any sign of a nuclear explosion, and we’re also sniffing the air for any sign of radioactivity,” says Comprehensive Test Ban Treaty Organization spokeswoman Annika Thunborg.

After the damaged nuclear reactors at Japan’s beleaguered power plant suffered from several explosions and began releasing radiation into the atmosphere, the organization began tracking the radiation.

According to Gerhard Wotawa, of the Austrian meteorological institute who has been studying data from the monitoring stations, the increases in radiation that the sensors are detecting are from Japan.

“Data like that I have never seen in my career, so it is pretty much clear where it comes from,” Wotawa said.

The sensors have detected several radioactive elements that are the byproducts of nuclear fission inside reactors like iodine-131 and cesium-137.

Experts studying the data picked up by the sensors disagree on the effect and size of the release.

Based on computer models on where the radiation will go, Wotawa says that the accident is releasing about as much radiation as the Chernobyl disaster in 1986.

While “the daily release is comparable to what was released in Chernobyl,” he said, “the effect of the power plant accident in Japan is not comparable to the effect of Chernobyl on the former Soviet Union.”

The radiation released during the Chernobyl accident contaminated land in all directions because the reactor was located inland. In contrast Japan’s Fukushima Daiichi reactor is located on the coast and winds are scattering radiation over the Pacific.

Harry Miley, a nuclear physicist at the Pacific Northwest National Laboratory in Washington state, has also been studying the data and disagrees with Wotawa’s findings.

“If I had to guess, I would say the release levels or more like Three Mile Island and less like Chernobyl, but we’ll see as time goes forward,” Miley said.

 

Miley also said that studying the data from the sensor network can tell researchers what occurred inside the Fukushima reactors.

He explains, “We might determine things like what was the temperature of the material when the radioactivity was emitted, which material it was. There are three reactors, and there are spent fuel pools and so forth — they’re all potential sources, and we should be able to nail down which source is which.”

The CTBT sensors are currently the only glimpse that scientists have on what occurred at the reactors as radiation levels on site are still far too high to measure directly.

Miley also allayed fears on the west coast of the United States about contamination levels when he said that the levels detected were not dangerous.

“The highest detection that we’ve gotten here in the U.S. has been far lower than the natural radioactivity that’s already there, so I don’t think there’s any increased risk to the U.S. public,” he says.