[The string of earthquake- and tsunami-triggered troubles at the Fukushima Daiichi plant began Friday, when a loss of grid power (caused by the earthquake) followed by a loss of backup diesel generators (caused by the tsunami) led to the failure of cooling systems needed to keep the reactor cores from overheating.]
By Steven Mufson,
Japan stepped closer to a full blown nuclear catastrophe Tuesday after the third explosion in four days appeared to have damaged equipment inside the reactor, apparently creating a path for the escape of radioactive materials, and a fire broke out at a separate reactor where spent fuel and hydrogen ignited. Tokyo Electric Power Co., owner of the seaside nuclear complex, ordered the evacuation of all but the 50 most essential workers and the Japanese Prime Minister addressed the nation urging people within 19 miles to stay indoors and remain calm.
Officials from Tokyo Electric Power, the plant owner, said the 6:14 a.m. explosion took place in the unit 2 reactor at or near the suppression pool, which collects water and radioactive elements from the containment vessel.
Experts said that, unlike the two previous explosions that destroyed outer buildings, this one might have damaged valves and drain pipes, possibly creating a path for radioactive materials to escape.
The explosion — more serious than the earlier blasts — was followed by a brief drop in pressure in the vessel and a spike in radioactivity outside the reactor to levels more than eight times what people ordinarily receive in a year, the company said. Tokyo Electric, which over the weekend said it had 1,400 people working at the complex, said it was evacuating all nonessential personnel, leaving about 50 people there.
Prime Minister Naoto Kan told the nation Tuesday morning that radiation had spread from the reactors and there was a very high risk of further radioactive material escaping. He urged people within 19 miles of the plant to remain indoors. He urged calm.
But Kan also said a fire had broken out at a fourth reactor unit.
The new setbacks came on the heels of a difficult Monday at Fukushima Daiichi unit 2. Utility officials there reported that four out of five water pumps being used to flood the reactor had failed and that the other pump had briefly stopped working. As a result, the company said, the fuel rods, normally covered by water, were completely exposed for 140 minutes, hastening the partial meltdown of them that most experts think is underway.
According to a report by the Kyodo news agency, the fifth pump was later restarted, and seawater mixed with boron was again injected in a desperate bid to cool the reactor, but the fuel rods remained partially exposed and ultra-hot. On Tuesday morning, Tokyo Electric said that 2.7 meters of the rods were still exposed.
The other four pumps were thought to have been damaged by a blast Monday that destroyed a building at the nearby unit 3 reactor, Kyodo reported. That blast, like one on Saturday at unit 1, was caused by a buildup in hydrogen generated by a reaction that took place when the zirconium alloy wrapped around the fuel rods was exposed to steam at 2,200 degrees Fahrenheit.
The International Atomic Energy Agency reported that injections of seawater into units 1 and 3 had been interrupted because of a low level in a seawater supply reservoir, but the seawater injections were later restored.
A commercial satellite photo of the complex showed piles of debris on top of units 1 and 3, which raised new fears about the condition of the pools where spent fuel is stored, especially at unit 1, where a design by General Electric placed the pool on top of the reactor but below the outer structure, which was destroyed. But the ability of workers to assess the damage was hindered by fears that another explosion might occur.
Last March, 1,760 tons of spent fuel were stored in the six pools — 84 percent of capacity, according to Tokyo Electric.
After Monday’s explosion at unit 3, Japanese government officials were quick to assert that it did not damage the core containment structure, and they said there would be little increase in radiation levels around the plant. But the explosion prompted Japan’s nuclear agency to warn those within 12 miles to stay indoors. The blast also injured 11 people, one seriously.
The string of earthquake- and tsunami-triggered troubles at the Fukushima Daiichi plant began Friday, when a loss of grid power (caused by the earthquake) followed by a loss of backup diesel generators (caused by the tsunami) led to the failure of cooling systems needed to keep the reactor cores from overheating.
The IAEA reported that Japan has evacuated 185,000 people from towns near the nuclear complex. The agency said Japan has distributed 230,000 units of stable iodine to evacuation centers from the area around the Fukushima Daiichi and Fukushima Daini nuclear power plants. The iodine has not been administered to residents; the distribution is a precautionary measure.
The ingestion of stable iodine can help to prevent the accumulation of radioactive iodine in the thyroid.
The U.S. 7th Fleet said Monday that some of its personnel, who are stationed 100 miles offshore from the Fukushima Daiichi plant, had come into contact with radioactive contamination. The airborne radioactivity prompted the fleet to reposition its ships and aircraft.
Using sensitive instruments, precautionary measurements were conducted on three helicopter aircrews returning to the USS Ronald Reagan after conducting disaster relief missions near Sen-dai. Those measurements identified low levels of radioactivity on 17 crew members.
The low-level radioactivity was easily removed from affected personnel by having them wash with soap and water, and later tests detected no contamination.
The political fallout spread all the way to the United States and Europe. German Chancellor Angel Merkel said Monday that she was suspending a deal that would have extended permits for 17 aging nuclear plants.
Many nuclear experts also called for a tougher scrutiny of U.S. plants, noting that the Japanese nuclear crisis exposed the limits of human ingenuity and imagination and pointed to the possible failure of the best-laid backup plans.
David Lochbaum, a nuclear engineer and director of the Nuclear Safety Program at the Union of Concerned Scientists, said in a conference call that in certain respects, the U.S. nuclear plants are not as prepared as the Japanese ones for a catastrophic power outage. After the earthquake and tsunami knocked out the electrical grid and backup generators, the Japanese engineers switched to batteries that could last for eight hours, he said.
“In this country, most of our reactors are only designed with battery capacity for four hours,” Lochbaum said. “Many of our reactors are in a situation where earthquakes, or hurricanes in the gulf, or ice storms in the northeast, or a tree in Cleveland, can cause an extensive blackout.”
The 2003 blackout that affected 52 million people across the upper Midwest, New York and parts of Canada was triggered when overheated wires sagged into trees in northeastern Ohio. Nine nuclear units switched to diesel backup generators, which are the size of locomotives without wheels.
Despite the cascade of equipment failures at the Fukushima Daiichi complex, some nuclear experts noted that the fuel rods there, whose temperature could have risen to as high as 4,000 degrees Fahrenheit, would lose some of their heat over the next few days and would probably remain encased, even in the worst-case scenario, in a secondary containment structure with several feet of steel and concrete walls.
But the new explosion raises new questions. With it impossible to see into the reactor vessels, officials were in large part speculating about what is happening inside by using a variety of gauges and indicators.
“Let’s hope they can get these reactors under control,” said Richard Lester, head of the department of nuclear science and engineering at the Massachusetts Institute of Technology. “They’re not there yet.”
Prime Minister Naoto Kan told the nation Tuesday morning that radiation had spread from the reactors and there was a very high risk of further radioactive material escaping. He urged people within 19 miles of the plant to remain indoors. He urged calm.
But Kan also said a fire had broken out at a fourth reactor unit.
The new setbacks came on the heels of a difficult Monday at Fukushima Daiichi unit 2. Utility officials there reported that four out of five water pumps being used to flood the reactor had failed and that the other pump had briefly stopped working. As a result, the company said, the fuel rods, normally covered by water, were completely exposed for 140 minutes, hastening the partial meltdown of them that most experts think is underway.
According to a report by the Kyodo news agency, the fifth pump was later restarted, and seawater mixed with boron was again injected in a desperate bid to cool the reactor, but the fuel rods remained partially exposed and ultra-hot. On Tuesday morning, Tokyo Electric said that 2.7 meters of the rods were still exposed.
The other four pumps were thought to have been damaged by a blast Monday that destroyed a building at the nearby unit 3 reactor, Kyodo reported. That blast, like one on Saturday at unit 1, was caused by a buildup in hydrogen generated by a reaction that took place when the zirconium alloy wrapped around the fuel rods was exposed to steam at 2,200 degrees Fahrenheit.
The International Atomic Energy Agency reported that injections of seawater into units 1 and 3 had been interrupted because of a low level in a seawater supply reservoir, but the seawater injections were later restored.
A commercial satellite photo of the complex showed piles of debris on top of units 1 and 3, which raised new fears about the condition of the pools where spent fuel is stored, especially at unit 1, where a design by General Electric placed the pool on top of the reactor but below the outer structure, which was destroyed. But the ability of workers to assess the damage was hindered by fears that another explosion might occur.
Last March, 1,760 tons of spent fuel were stored in the six pools — 84 percent of capacity, according to Tokyo Electric.
After Monday’s explosion at unit 3, Japanese government officials were quick to assert that it did not damage the core containment structure, and they said there would be little increase in radiation levels around the plant. But the explosion prompted Japan’s nuclear agency to warn those within 12 miles to stay indoors. The blast also injured 11 people, one seriously.
The string of earthquake- and tsunami-triggered troubles at the Fukushima Daiichi plant began Friday, when a loss of grid power (caused by the earthquake) followed by a loss of backup diesel generators (caused by the tsunami) led to the failure of cooling systems needed to keep the reactor cores from overheating.
The IAEA reported that Japan has evacuated 185,000 people from towns near the nuclear complex. The agency said Japan has distributed 230,000 units of stable iodine to evacuation centers from the area around the Fukushima Daiichi and Fukushima Daini nuclear power plants. The iodine has not been administered to residents; the distribution is a precautionary measure.
The ingestion of stable iodine can help to prevent the accumulation of radioactive iodine in the thyroid.
The U.S. 7th Fleet said Monday that some of its personnel, who are stationed 100 miles offshore from the Fukushima Daiichi plant, had come into contact with radioactive contamination. The airborne radioactivity prompted the fleet to reposition its ships and aircraft.
Using sensitive instruments, precautionary measurements were conducted on three helicopter aircrews returning to the USS Ronald Reagan after conducting disaster relief missions near Sen-dai. Those measurements identified low levels of radioactivity on 17 crew members.
The low-level radioactivity was easily removed from affected personnel by having them wash with soap and water, and later tests detected no contamination.
The political fallout spread all the way to the United States and Europe. German Chancellor Angel Merkel said Monday that she was suspending a deal that would have extended permits for 17 aging nuclear plants.
Many nuclear experts also called for a tougher scrutiny of U.S. plants, noting that the Japanese nuclear crisis exposed the limits of human ingenuity and imagination and pointed to the possible failure of the best-laid backup plans.
David Lochbaum, a nuclear engineer and director of the Nuclear Safety Program at the Union of Concerned Scientists, said in a conference call that in certain respects, the U.S. nuclear plants are not as prepared as the Japanese ones for a catastrophic power outage. After the earthquake and tsunami knocked out the electrical grid and backup generators, the Japanese engineers switched to batteries that could last for eight hours, he said.
“In this country, most of our reactors are only designed with battery capacity for four hours,” Lochbaum said. “Many of our reactors are in a situation where earthquakes, or hurricanes in the gulf, or ice storms in the northeast, or a tree in Cleveland, can cause an extensive blackout.”
The 2003 blackout that affected 52 million people across the upper Midwest, New York and parts of Canada was triggered when overheated wires sagged into trees in northeastern Ohio. Nine nuclear units switched to diesel backup generators, which are the size of locomotives without wheels.
Despite the cascade of equipment failures at the Fukushima Daiichi complex, some nuclear experts noted that the fuel rods there, whose temperature could have risen to as high as 4,000 degrees Fahrenheit, would lose some of their heat over the next few days and would probably remain encased, even in the worst-case scenario, in a secondary containment structure with several feet of steel and concrete walls.
But the new explosion raises new questions. With it impossible to see into the reactor vessels, officials were in large part speculating about what is happening inside by using a variety of gauges and indicators.
“Let’s hope they can get these reactors under control,” said Richard Lester, head of the department of nuclear science and engineering at the Massachusetts Institute of Technology. “They’re not there yet.”
JAPAN -- The massive earthquake that struck northeast Japan last March 11 has shortened the length Earth's day by a fraction and shifted how the planet's mass is distributed.
A new analysis of the 8.9-9.0 magnitude earthquake in Japan has found that the intense temblor has accelerated Earth's spin, shortening the length of the 24-hour day by 1.8 microseconds, according to geophysicist Richard Gross at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
Gross refined his estimates of the Japan quake's impact – which previously suggested a 1.6-microsecond shortening of the day – based on new data on how much the fault that triggered the earthquake slipped to redistribute the planet's mass. A microsecond is a millionth of a second.
"By changing the distribution of the Earth's mass, the Japanese earthquake should have caused the Earth to rotate a bit faster, shortening the length of the day by about 1.8 microseconds," Gross told SPACE.com in an e-mail. More refinements are possible as new information on the earthquake comes to light, he added.
The scenario is similar to that of a figure skater drawing her arms inward during a spin to turn faster on the ice. The closer the mass shift during an earthquake is to the equator, the more it will speed up the spinning Earth.
One Earth day is about 24 hours, or 86,400 seconds, long. Over the course of a year, its length varies by about one millisecond, or 1,000 microseconds, due to seasonal variations in the planet's mass distribution such as the seasonal shift of the jet stream.
The initial data suggests Friday's earthquake moved Japan's main island about 8 feet, according to Kenneth Hudnut of the U.S. Geological Survey. The earthquake also shifted Earth's figure axis by about 6 1/2 inches (17 centimeters), Gross added.
The Earth's figure axis is not the same as its north-south axis in space, which it spins around once every day at a speed of about 1,000 mph (1,604 kph). The figure axis is the axis around which the Earth's mass is balanced and the north-south axis by about 33 feet (10 meters).
"This shift in the position of the figure axis will cause the Earth to wobble a bit differently as it rotates, but will not cause a shift of the Earth's axis in space – only external forces like the gravitational attraction of the sun, moon, and planets can do that," Gross said.
This isn't the first time a massive earthquake has changed the length of Earth's day. Major temblors have shortened day length in the past.
The 8.8-magnitude earthquake in Chile last year also sped up the planet's rotation and shortened the day by 1.26 microseconds. The 9.1 Sumatra earthquake in 2004 shortened the day by 6.8 microseconds.
And the impact from Japan's 8.9-magnitude temblor may not be completely over. The weaker aftershocks may contribute tiny changes to day length as well.
The March 11 quake was the largest ever recorded in Japan and is the world's fifth largest earthquake to strike since 1900, according to the USGS. It struck offshore about 231 miles (373 kilometers) northeast of Tokyo and 80 miles (130 km) east of the city of Sendai, and created a massive tsunami that has devastated Japan's northeastern coastal areas. At least 20 aftershocks registering a 6.0 magnitude or higher have followed the main temblor.
"In theory, anything that redistributes the Earth's mass will change the Earth's rotation," Gross said. "So in principle the smaller aftershocks will also have an effect on the Earth's rotation. But since the aftershocks are smaller their effect will also be smaller."
