Workers Injured, Smoke Reported at Japanese Nuclear Plant Facing Possible Meltdown
If Fuel Rods Remain Exposed, They Will be Damaged, Releasing Radioactivity
Several workers at a nuclear plant facing a possible meltdown may have been injured after shaking and smoke was reported, Japanese officials said.
It is unclear if an explosion occurred and officials were investigating the cause, Fukushima Prefecture official Masato Abe told the Associated Press.
But Tokyo Electric said an explosion happened in the first reactor, according to local media reports.
Broadcast images show the plant's the skeleton of the structure remains.
NHK reported at least four people were injured.
This incident comes as the level of water used to cool a nuclear reactor damaged in Friday's 8.9-magnitude earthquake and tsunami dropped to an alarming level today, according to the Nuclear and Industrial Safety Agency, heightening fears of a larger nuclear disaster.
As of 11:20 a.m. local time, a part of the "fuel assembly" of fuel rods at the Fukushima Daiichi plant's No. 1 reactor was exposed above water, with a maximum exposure of about 90 centimeters.
If the fuel rods remain exposed, they will be damaged, releasing radioactivity.
"This is extremely serious," said Joseph Cirincione, president of the Ploughshares Fund and an expert on national security and international policy. "The best case at this point would still be the worst incident since Chernobyl.
"We are in uncharted territory," he said. "It is possible that this can be contained and we would have a very bad nuclear contamination event. But if the water levels continue to drop and the rods are exposed further it could lead to a core meltdown. The core would melt through the steel holding structure and plunge in a burning, molten mass into the concrete containment structure. If the structure is sound, it could contain the mass, if it has been structurally damaged, then it, too, could breech and we would have a massive, radioactive release."
About 27,000 liters of water, including water stored for firefighting, was being pumped into the reactor via makeshift pumps and other means in order to raise the water level above the reactor's nuclear fuel, NISA said.
"NISA just confirmed that the fuel may be partially melting," Dr. Tatsujiro Suzuki, vice-chairman of the Japan Atomic Energy Commission told ABC News. "The question is whether the situation is getting worse or not. It is reported that the level of water is declining (bad news) but pressure is also decreasing (good news). So, efforts to contain the event (need water) may be working. It is also stated that the amount of radioactivity is still small so that the general public does not need to be concerned at present."
Nevertheless, the government continued to ask everyone around the plant, about 200 miles northeast of Tokyo, to "calmly" evacuate, Japanese broadcaster NHK reported. An evacuation order for a 10-kilometer radius around the plant had been issued earlier.
The Fukushima Daiichi plant was one of two run by the Tokyo Electric Power Co. whose cooling systems were damaged in the earthquake and tsunami. At least two reactors at the plant and three at the nearby Fukushima Daini plant had damaged cooling systems, the Associated Press reported.
There also was an evacuation order in effect for residents living within a mile of the Daini plant.
But the situation at the Fukushima Daiichi reactor No. 1 was reported to be the most dire. Radiation inside the reactor surged to 1,000 times its normal level after Friday's earthquake knocked out power to its cooling system, and the tsunami floods have hampered efforts to get it restored.
Heat-induced pressure built up inside the crippled reactor after the reactor lost power, automatically shut down and the cooling system failed. The situation at the reactor and the four others with compromised cooling systems prompted officials to declare nuclear emergencies.
Scientists said that even though the No. 1 reactor at the Fukushima Daiichi site, in particular, had stopped producing energy, its fuel continued to generate heat and needed steady levels of coolant to prevent it from overheating and triggering a dangerous cascade of events.
"You have to continue to supply water. If you don't, the fuel will start to overheat and could melt," said Edwin Lyman, a senior staff scientist in the Global Security program at the Union of Concerned Scientists in Washington, D.C.
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A meltdown could lead to a breach of the reactor's steel containment vessel and allow radiation to escape into an outer, concrete containment building, or even into the environment.
"Up to 100 percent of the volatile radioactive Cesium-137 content of the pools could go up in flames and smoke, to blow downwind over large distances," said Kevin Kamps, a nuclear waste specialist at Beyond Nuclear, which is an advocacy group that opposes nuclear weapons and power.
"Given the large quantity of irradiated nuclear fuel in the pool, the radioactivity release could be worse than the Chernobyl nuclear reactor catastrophe of 25 years ago."
The Kyodo News Service reported Friday that some radioactive material already may have escaped, citing reports from the Japanese Nuclear Safety Agency that radiation levels outside the plan have been eight times the normal level. Experts said that level of exposure is not dangerous to the general population.
"You've got to take all potential precautions," President Obama told reporters Friday when asked about vulnerability of the Japanese nuclear power facilities. "And I've asked Steve Chu, our energy secretary, to be in close contact with their personnel to provide any assistance that's necessary, but also to make sure that if in fact there have been breaches in the safety system on these nuclear plants, that they're dealt with right away."
Experts say cooling the reactor's core to minimize pressure inside the containment structure is a top priority. Japanese authorities have been trying to connect diesel-powered generators to restore the water pumps inside the reactor but have been hampered by the floods.
"If you have something that generates heat and you don't cool it off or release the steam, you're in trouble," said nuclear consultant Mycle Schneider, who compared the situation to a pressure cooker.
The risk is a rapid rise in heat that would leave the core uncovered -- something that may have begun Saturday.
"If it's not covered with water, it can start melting very quickly," Schneider said.
Meanwhile, officials performed a controlled release of some slightly radioactive vapor that has been building up inside the containment structure, the Associated Press reported.
The release would allow harmful material to escape into the environment, but not at levels as great as if there was a massive containment failure, Lyman said.
"It's good they evacuated -- let's put it that way," Lyman said. "All indications are that this is a very serious event."
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