Radiation Level 1,000 Times Too High at Japanese Nuclear Plant

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Radiation Level 1,000 Times Too High at Japanese Nuclear Plant

By Wolchover , Life's Little Mysteries Staff Writer, LiveScience.com |

LiveScience.com – 1 hour 0 minutes ago

The radiation level around a nuclear reactor at the Fukushima nuclear facility

near Tokyo has risen to 1,000 times its normal level since this morning's

earthquake blew out the plant's cooling system. Technicians at the plant are

preparing to release steam that has been vaporized by heat from the nuclear core

in order to lower the pressure around the core and prevent a meltdown.

That carries a risk of leaking radiation, too. " It's possible that radioactive

material in the reactor vessel could leak outside but the amount is expected to

be small and the wind blowing towards the sea will be considered, " Chief Cabinet

Secretary Yukio Edano told a news conference.

The 8.9-magnitude earthquake that shook Japan early March 11 caused cooling

system malfunctions at two nuclear reactors, one at the Tokyo Electric Power

Co.'s Fukushima Daiichi power plant near Tokyo and the Tohoku Electric Power Co.

facility in Onagawa. Fearing radiation leaks, the government ordered the

evacuation of thousands of residents within a 1.8-mile radius of the Fukushima

facility this morning.

Eleven reactors nearest the quake's epicenter automatically shut down upon

sensing vibrations in the early hours of March 11. " Reactors shut themselves

down automatically when something called 'ground acceleration' is registered at

a certain point, which is usually quite small. It will instantly drop control

rods into the [nuclear] core, " Professor Tim Albram, a nuclear fuel engineer at

the University of Manchester in the U.K., explained to the press.

Those control rods block neutrons from entering the core and inducing the

fission reactions that produce nuclear energy. When the rods drop into the core,

the heat put out by the nuclear fuel rods they surround plummets instantly,

reducing the core's temperature to less than 5 percent of normal in a matter of

seconds.

A base level of heat from nuclear decay continues to flow off the rods, however,

and that's the problem in the Fukushima and Onagawa plants. Officials say they

do not have enough electric power to pump water through the cooling systems and

dissipate the extra heat.

Mark Hibbs, a nuclear expert at the Carnegie Endowment for International Peace,

told Reuters that there is serious concern in Japan whether the cooling of the

core and removal of residual heat could be assured. " If that does not happen, if

heat is not removed, there is a definite danger of a core melt ... fuel will

overheat, become damaged and melt down. "

" Even if fuel rods melt and the pressure inside the reactor builds up, radiation

would not leak as long as the reactor container functions well, " Tomoko

Murakami, leader of the nuclear energy group at Japan's Institute of Energy

Economics, told Reuters. But the pressure can only build up so much before steam

must be released, and along with it, some radiation.