Radioactivity from Japan's Nuclear Plants
Japan Radiation Unlikely to Reach U.S.: Officials
March 13, 2011AFP - Radiation from nuclear plants damaged in Japan's earthquake is unlikely to reach US territory in harmful amounts, US nuclear officials say.
"Given the thousands of miles between the two countries, Hawaii, Alaska, the US Territories and the US west coast are not expected to experience any harmful levels of radioactivity," the federal Nuclear Regulatory Commission (NRC) said in a statement.The office also said it sent two boiling-water reactor experts as part of a US Agency for International Development (USAID) emergency team helping respond to the crisis in Japan.
"All the available information indicates weather conditions have taken the small releases from the Fukushima reactors out to sea away from the population," the statement read.
The NRC is coordinating with the US Department of Energy and other federal agencies in providing "whatever assistance the Japanese government requests" as they respond to conditions at several nuclear power plant sites following the March 11 earthquake and tsunami, the statement read.
Japan is battling a feared meltdown of two reactors at a quake-hit nuclear plant, in the wake of the disaster.
An explosion at the ageing Fukushima No 1 atomic plant blew apart the building housing one of its reactors on Saturday, one day after the biggest quake ever recorded in Japan unleashed a monster tsunami.
The emergency escalated as crews struggled to prevent overheating at a second reactor where the cooling system has also failed, and the government warned that it too could be hit with a blast.
Japan Races to Avert Multiple Meltdowns
March 13, 2011AP - Japanese officials warned of a possible second explosion Sunday at a nuclear plant crippled by the earthquake and tsunami as they raced to stave off multiple reactor meltdowns, but they provided few details about whether they were making progress. More than 180,000 people have evacuated the area, and up to 160 may have been exposed to radiation.
Four nuclear plants in northeastern Japan have reported damage, but the danger appeared to be greatest at the Fukushima Dai-ichi nuclear complex, where one explosion occurred Saturday and a second was feared. Operators have lost the ability to cool three reactors at Dai-ichi and three more at another nearby complex using usual procedures, after the quake knocked out power and the tsunami swamped backup generators.
Chief Cabinet Secretary Yukio Edano said Sunday that a hydrogen explosion could occur at Dai-ichi's Unit 3, the latest reactor to face a possible meltdown. That would follow a hydrogen blast Saturday in the plant's Unit 1.
"At the risk of raising further public concern, we cannot rule out the possibility of an explosion," Edano said. "If there is an explosion, however, there would be no significant impact on human health."Operators have been dumping seawater into units 1 and 3 in a last-ditch measure to cool the reactors. They were getting water into the other four reactors with cooling problems without resorting to corrosive sea water, which likely makes the reactors unusable.
Edano said residents within about 12 miles (20 kilometers) of the Dai-ichi plant were ordered to evacuate as a precaution, and the radioactivity released into the environment so far was so small it didn't pose any health threats.
Such statements, though, did little to ease public worries.
"First I was worried about the quake," said Kenji Koshiba, a construction worker who lives near the plant. "Now I'm worried about radiation." He spoke at an emergency center in Koriyama, about 40 miles (60 kilometers) from the most troubled reactors and 125 miles (190 kilometers) north of Tokyo.At the makeshift center set up in a gym, a steady flow of people — mostly the elderly, schoolchildren and families with babies — were met by officials wearing helmets, surgical masks and goggles.
About 1,500 people had been scanned for radiation exposure, officials said.
Up to 160 people, including 60 elderly patients and medical staff who had been waiting for evacuation in the nearby town of Futabe, and 100 others evacuating by bus, might have been exposed to radiation, said Ryo Miyake, a spokesman from Japan's nuclear agency. It was unclear whether any cases of exposure had reached dangerous levels.
A foreign ministry official briefing reporters said radiation levels outside the Dai-ichi plant briefly rose above legal limits, but had since declined significantly.
Edano said none of the Fukushima Dai-ichi reactors was near the point of complete meltdown, and he was confident of escaping the worst scenarios.
Officials, though, have declared states of emergency at the six reactors where cooling systems were down — three at Dai-ichi and three at the nearby Fukushima Daini complex. The U.N. nuclear agency said a state of emergency was also declared Sunday at another complex, the Onagawa power plant, after higher-than-permitted levels of radiation were measured there. It said Japan informed it that all three reactors there were under control.
A pump for the cooling system at yet another nuclear complex, the Tokai Dai-Ni plant, also failed after Friday's quake but a second pump operated normally as did the reactor, said the utility, the Japan Atomic Power Co. It did not explain why it did not announce the incident until Sunday.
Edano denied there had been a meltdown in the Fukushima Dai-ichi complex, but other officials said the situation was not so clear.
Hidehiko Nishiyama, a senior official of the Economy, Trade and Industry Ministry, indicated the reactor core in Unit 3 had melted partially, telling a news conference,
"I don't think the fuel rods themselves have been spared damage," according to the Kyodo News agency.A complete meltdown — the melting of the radioactive core — could release uranium and dangerous contaminants into the environment and pose major, widespread health risks.
The steel reactor vessel could melt or break from the heat and pressure. A concrete platform underneath the reactor is supposed to catch the molten metal and nuclear fuel, but the intensely hot material could set off a massive explosion if water has collected on the platform. Radioactive material also could be released into the ground if the platform fails.
The explosion that destroyed the walls and ceiling of Dai-ichi Unit 1's containment building was much less serious that a meltdown would be — in fact, it was operators' efforts to avoid a meltdown that caused it.
Officials vented steam from the reactor to reduce pressure, and were aware that there was an explosion risk because the steam contained hydrogen, said Shinji Kinjo, spokesman for the government's Nuclear and Industrial Safety Agency. The explosion occurred when hydrogen reacted with oxygen outside the reactor.
It is unclear how far the impact of a meltdown might reach. In the United States, local communities plan for evacuation typically within 10 miles of a nuclear plant. However, states must be ready to cope with contamination of food and water as far as 50 miles away. Radioactivity can also be carried to faraway places by the winds, as it was in the 1986 Chernobyl disaster, though it will become increasingly diffuse. Acute radiation deaths would normally be expected only much closer to the plant.
The reactor that exploded at Chernobyl, sending a cloud of radiation over much of Europe, was not housed in a sealed container as those at Dai-ichi are. The Japanese reactors also do not use graphite, which burned for several days at Chernobyl.
Japan's nuclear crisis was triggered by twin disasters on Friday, when an 8.9-magnitude earthquake, the most powerful in the country's recorded history, was followed by a tsunami that savaged its northeastern coast with breathtaking speed and power.
More than 1,400 people were killed and hundreds more were missing, according to officials, but police in one of the worst-hit areas estimated the toll there alone was more than 10,000.
All of the reactors in the region shut down automatically when the earthquake hit. But with backup power supplies also failing, shutting down the reactors is just the beginning of the problem, scientists said.
"You need to get rid of the heat," said Friedrich Steinhaeusler, a professor of physics and biophysics at Salzburg University and an adviser to the Austrian government on nuclear issues. "You are basically putting the lid down on a pot that is boiling."Japan's nuclear safety agency said 1,450 workers were at the Dai-ichi plant on Sunday, its usual staffing. The workers were in protective gear and were taking shorter turns than usual in units 1 and 3 to limit their exposure, agency spokesman Yoshihiro Sugiyama said.
"They have a window of opportunity where they can do a lot," he said, such as using sea water as an emergency coolant. But if the heat is not brought down, the cascading problems can eventually be impossible to control. "This isn't something that will happen in a few hours. It's days."
The emergencies at the nuclear plants have led to an electricity shortage in Japan, where nearly 2 million households were without power Sunday. Starting Monday, power will be rationed with rolling blackouts in several cities, including Tokyo.
Japan has a total of 55 reactors spread across 17 complexes nationwide.
Another Reactor at Fukushima Nuke Plant Loses Cooling Functions
March 13, 2011Kyodo News - Tokyo Electric Power Co. said Sunday another reactor of its quake-hit Fukushima nuclear power plants had lost its cooling functions, while at least 15 people at a nearby hospital were found to have been exposed to radioactivity.
The utility supplier notified the government early Sunday morning that the No. 3 reactor at the No. 1 Fukushima plant had lost the ability to cool the reactor core. The reactor is now in the process of releasing radioactive steam, according to top government spokesman Yukio Edano.
It was the sixth reactor overall at the Fukushima No. 1 and No. 2 plants to undergo cooling failure since the massive earthquake and ensuing tsunami struck Japan on Friday.
The disaster raised fears over radioactive leaks from the plants after cooling systems there were hampered, most seriously at the No. 1 reactor.
An explosion Saturday at the No. 1 plant blew away the roof and the walls of the building housing the No. 1 reactor's container.
The government and nuclear authorities said there was no damage to the steel container housing the troubled No. 1 reactor, noting that the blast occurred as vapor from the container turned into hydrogen and mixed with outside oxygen.
Tokyo Electric Power has begun new cooling operations to fill the reactor with sea water and pour in boric acid to prevent an occurrence of criticality. Chief Cabinet Secretary Edano said in a press conference Sunday morning that there had been no major changes in the results of monitoring radioactivity near the No. 1 reactor.
Following the explosion, the authorities expanded from 10 kilometers to 20 km the radius of the evacuation area for residents living in the vicinity of the Fukushima plants.
The Fukushima prefectural government said Saturday that three people had their clothes contaminated with radioactive substances while fleeing from the No. 1 nuclear plant.
The Fire and Disaster Management Agency said Sunday that 15 people were found to have been contaminated at a hospital located within 10 km from the No. 1 reactor. Edano said there was a possibility that nine people who fled on a bus had been exposed to radioactivity.
Japan Quake: Fears of Second Nuclear Reactor Blast
March 13, 2011BBC News - There is a risk of a second explosion at the quake-hit Fukushima power station, Japanese officials have said.
However, chief cabinet secretary Yukio Edano said the facility could withstand the impact and the nuclear reactor itself would not be damaged.
Technicians are frantically battling to cool reactor 3 following a blast at the building housing reactor 1 on Saturday.
A state of emergency has also been declared at the Onagawa plant to the north of Fukushima.
The first -- or lowest -- state of emergency was reported by Tohoku Electric Power Company, said the UN nuclear watchdog the IAEA.
It was declared "as a consequence of radioactivity readings exceeding allowed levels in the area surrounding the plant. Japanese authorities are investigating the source of radiation," the IAEA said on its website.
"The authorities have informed the IAEA that the three reactor units at the Onagawa nuclear power plant are under control."
The Japanese government has doubled the size of the evacuation zone around Fukushima-Daiichi (Fukushima I plant) to 20km (12.4 miles), and some 80,000 people are being moved out of the zone.
With the loss of power at reactor 3, and with its valves and pumps damaged by the tsunami, emergency workers were pumping in seawater mixed with boron -- which disrupts nuclear chain reactions -- to cool the rods.
But this creates a build-up of radioactive steam containing hydrogen which must be vented to relieve pressure inside the reactor vessel -- risking a blast.
"At the risk of raising further public concern, we cannot rule out the possibility of an explosion," Mr Edano said, according to AP news agency.Experts say as long as authorities can keep fuel rods in the core covered with water, they should be able to avoid a major disaster.
"If there is an explosion, however, there would be no significant impact on human health."
But Mr Edano admitted that the tops of the rods had briefly been exposed.
Technicians opened valves, allowing small amounts of radioactive vapour to escape in a bid to reduce the pressure in the unit. They performed a similar operation on the first reactor, hours before the explosion that wrecked the building it was housed in.
Twenty-two people were exposed to radiation following that blast, and scores more are feared to have been exposed.
The plant's operators, Tokyo Electric Power (Tepco), said radiation levels around the plant had temporarily risen above permissible limits.
Authorities deny their health has been put at risk, but the BBC's Chris Hogg says many people do not believe such reassurances.
Health authorities were conducting screenings at evacuation shelters across Fukushima prefecture.
Japan's nuclear agency graded the situation at the Fukushima plant as a Level 4 incident on the International Nuclear and Radiological Events Scale (Ines). Level 4 incidents normally involve at least one death from radiation, although no-one at the plant has died.
The BBC's Chris Hogg in Tokyo says a meltdown at reactor 3 would be potentially more serious than at the other reactors, because it is fuelled by plutonium and uranium, unlike the other units which carry only uranium.
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