Japan Nuclear Plant Troubles Deepen

YUKA HAYASHI PHRED DVORAK

As the death toll rises in Japan in the aftermath of Friday's earthquake, a nuclear disaster threat looms as fuel rods at the Fukushima Daiichi Nuclear Plant became fully exposed. Also, Asian countries with planned or existing plants are on alert.

Japan's unfolding nuclear-power crisis deepened Monday, with a new explosion and accelerated overheating at one reactor in Fukushima and the start of cooling troubles at another.

The explosion took place Monday morning at the No. 3 reactor of the Fukushima Daiichi nuclear complex, the same place where a failure to cool overheated fuel rods at the No. 1 reactor resulted in a similar blast on Saturday. That explosion also damaged a pump used to bring in sea water for added cooling, the government's Nuclear and Industrial Safety Agency said at a briefing Monday evening. The agency said the fuel rods at the No. 3 reactor are now fused together.

Monday afternoon, a third reactor at the complex began experiencing similar cooling problems, said chief government spokesman Yukio Edano. Plant operator Tokyo Electric Power Co. is preparing to flood that reactor, known as the No. 2 reactor, with seawater in an attempt to bring the temperature down, he said.

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A second hydrogen explosion occurred at a beleaguered nuclear power plant in Japan's Fukushima prefecture. Video courtesy of Reuters

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In all three cases, the problems have arisen after levels of water needed to cool reactor fuel rods fell. That exposed the rods and released highly combustible hydrogen gas, which eventually built up in the concrete buildings surrounding each reactor.

So far, the explosions have destroyed those buildings but left the steel containers around each reactor intact, Mr. Edano said. Six people were injured, one seriously, after Monday's explosion, Mr. Edano said. The government said there hasn't been a large increase in radiation following the explosion.

Televisions showed smoke billowing out of the No. 3 reactor at the Fukushima Daiichi plant shortly after 11 a.m. local time.

Officials are continuing to struggle to prevent meltdowns at both the No. 1 and No. 3 damaged reactors, saying their fuel rods may have been critically damaged by overheating.

They stressed, however, that containment vessels housing the reactors remained intact and that there were no signs of the radiation leakage that would accompany a major meltdown. Monday, they reported that radiation levels remained far below peaks seen over the weekend.

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Officials were scrambling early Monday to contain numerous potential crises--from water and fuel shortages in hard-hit areas to emergency financial measures as markets reopened. Still, the problem with the country's nuclear plants stood out as perhaps the most worrisome development.

Tokyo Electric's Fukushima Daiichi power plant in northern Japan was damaged in Friday's massive earthquake and tsunami. Monday, authorities were injecting seawater into the three overheating reactors to replace cooling water they had lost —- a procedure that would render them unusable.

At a separate Fukushima Tepco facility —- the Daini plant about six miles away —- three of its four reactors have reported elevated temperatures.

"We continue to face very worrisome situations at the Fukushima nuclear power plants," Prime Minister Naoto Kan said at a news conference Sunday evening. He didn't elaborate further.

One person briefed on the situation said that critical issues remained at one facility, with troubling amounts of fuel exposed.

Friday's 8.9 magnitude earthquake exceeded the level that Tokyo's plants are designed to withstand. Masataka Shimizu, chief executive of Tokyo Electric Power Co., which operates most of the affected nuclear reactors in Tohoku, said Sunday: "We could argue we were adequately prepared for tsunami within the size of our previous assumption. But the latest tsunami was of a level that far exceeded our assumption."

For those near the troubled Fukushima complex, the government said Sunday that radiation tests had begun on everyone who was evacuated from the vicinity.

Roughly 70,000 to 80,000 people living within in a radius of about 12 miles of the two plants have been asked to leave the area; the 500 or so who remained were evacuated following the latest explosion. The government said Saturday they were preparing to stockpile iodine used to treat radiation sickness, "just in case."

Mr. Edano said nine people were affected by radiation released from the No. 1 reactor at the time of Saturday's explosion, and that there are no health concerns for now.

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Soon after the explosion, the radiation level outside the No. 1 reactor rose to 1,015 microsievert—the equivalent of being exposed to the maximum allowable level for a full year in a single day. The level has since fallen sharply.

Concerns have in the past day focused on Fukushima Daiichi's No. 3 reactor, the one that experienced Monday's explosion. The Fukushima Daiichi plant is located about 150 miles from Tokyo.

Despite the effort to inject seawater, the level of cooling water in the reactor remained low—for reasons that aren't clear—exposing fuel rods.

The government Nuclear and Industrial Safety Agency said late Sunday that roughly a half of the length of their more than 12-foot-long fuel rods were outside of the cooling water—making the fuel vulnerable to serious damage.

Officials started pouring seawater into the No. 3 reactor Sunday afternoon, following a similar step taken with the No. 1 reactor on Saturday, which appears to have stabilized the situation. But the same measures seemed to have had the same effect of causing an explosion in the facility without doing more damage to the core reactor. Officials said that, despite the explosion, there was no significant increase in measured radiation.

Nuclear experts are particularly worried about the No. 3 unit, supplied by Toshiba Corp., because it uses an unconventional fuel called MOX fuel, short for mixed oxide.

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Japan Evacuees Scanned for Radiation Exposure

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Thousands of evacuees from areas around Japan's Fukushima nuclear power plant were scanned for radiation exposure, though the Japanese government insists radiation levels are low. Video courtesy of Reuters

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Smoke rose Saturday following an explosion at a nuclear power plant in Japan's Fukushima prefecture. Video courtesy of Reuters

It is made by mixing low-enriched uranium with plutonium that has been recycled from a global stockpile of defunct nuclear weapons. This recycling is part of an international effort to decrease the number of nuclear weapons and move from "megatons to megawatts."

MOX fuel has greater concentrations of "actinides," or radioactive elements and runs hotter than conventional fuel, so a shut down plant would have to deal with more "decay" or residual heat from fuel rods.

There are at least two dozen MOX-burning nuclear plants globally. But some experts believe that an accident at a nuclear power plant utilizing MOX fuel could be more dangerous than one that uses conventional uranium-based fuel.

Japanese officials released no new information overnight about the Fukushima situation. But a foreign observer briefed on the situation early Monday said reactor No. 3 remained critical.

"The fuel is getting hotter and hotter," this person said.

The more of the fuel that is exposed, the hotter the fuel gets, converting even more of the coolant into steam, and worsening the situation, by exposing even more fuel to the melting and heating process, this person said. He described the crisis as proceeding like a freight train, that gathers momentum as the crisis continues.

A similar crisis in reactor No. 1 at the same nuclear power station appeared to be slowing, he said, but it is unclear if the crisis in reactor one is completely past. That unit was supplied by General Electric Co.

With the world's focus on the Fukushima complex, there were ominous reports Sunday and Monday about troubles spreading two other Japanese reactors—the Onagawa power plant in Sendai and Tokai No. 2 nuclear plant closer to Tokyo—but both later proved to be only temporary concerns.

The United Nations nuclear agency issued a statement Sunday saying a low-level emergency had been reported at Onagawa due to briefly elevated radiation levels detected outside the plant. But officials later concluded the radiation had nothing to do with any problems at the plant, and the emergency warning was rescinded.

In Tokai, the plant's operator said early Monday that a reactor-cooling pump was not working after being hit by the quake-driven tsunami.

Japan Atomic Power Co. said the reactor at the Tokai plant in Ibaraki Prefecture automatically shut down following Friday's earthquake. However, an additional water pump is working normally and "is safely cooling the reactor down," a company official said.