Fukushima radiation could be ocean risk

DAVIS, Calif., Jan. 26 (UPI) -- Seawater used to cool nuclear fuel at Japan's Fukushima nuclear plant after the 2011 tsunami could have corroded the fuel and spread radiation, scientists say.

Although probably the best action to take at the time, U.S. researchers said, they've discovered a new way in which seawater can corrode nuclear fuel, forming uranium compounds capable of traveling long distances either in solution or as very small particles.

"This is a phenomenon that has not been considered before," said chemistry professor Alexandra Navrotsky at the University of California, Davis.

"We don't know how much this will increase the rate of corrosion, but it is something that will have to be considered in the future."

Uranium in nuclear fuel rods is in a chemical form that is "pretty insoluble" in water, Navrotsky said, but when radiation converts water into peroxide, a powerful oxidizing agent, uranium can be converted into uranium-VI, which in seawater is stable enough to persist in solution or as small particles.

The uranium-VI could form on the surface of a fuel rod exposed to seawater and then be transported away, surviving in the environment for months or years before reverting to more common forms of uranium and settling to the bottom of the ocean, researchers said.

There is no data yet on how fast it would break down in the environment, Navrotsky said in a university release Thursday.