Saturday, March 12, 2011 by Agence France-Presse
US Experts: 'Chernobyl-Like' Crisis for Japan
WASHINGTON - US nuclear experts warned Saturday that pumping sea water to cool a quake-hit Japanese nuclear reactor was an "act of desperation" that may foreshadow a Chernobyl-like disaster.
Official in protective gear talks to a woman who is from the evacuation area near the Fukushima Daini nuclear plant in Koriyama March 13, 2011. Japan battled to contain a radiation leak at an earthquake-crippled nuclear plant on Sunday, but faced a fresh threat with the failure of the cooling system in a second reactor. REUTERS/Kim Kyung-Hoon Several experts, in a conference call with reporters, also predicted that regardless of the outcome at the Fukushima No. 1 atomic plant crisis, the accident will seriously damage the nuclear power renaissance.
"The situation has become desperate enough that they apparently don't have the capability to deliver fresh water or plain water to cool the reactor and
stabilize it, and now, in an act of desperation, are having to resort to diverting and using sea water," said Robert Alvarez, who works on nuclear disarmament at the Institute for Policy Studies.
"I would describe this measure as a 'Hail Mary' pass," added Alvarez, using American football slang for a final effort to win the game as time expires.
An 8.9 magnitude earthquake that struck Japan on Friday set off the emergency at the plant, which was then hit by an explosion Saturday that prompted an evacuation of the surrounding area.
Workers doused the stricken reactor with sea water to try to avert catastrophe, after the quake knocked out power to the cooling system.
What occurred at the plant was a "station blackout," which is the loss of offsite air-conditioning power combined with the failure of onsite power, in this case diesel generators.
"It is considered to be extremely unlikely but the station blackout has been one of the great concerns for decades," said Ken Bergeron, a physicist who has worked on nuclear reactor accident simulation.
"We're in uncharted territory," he said.
The reactor has been shut down but the concern is the heat in the core, which can melt if it's not cooled. If the core melts through the reactor vessel, Bergeron explained, it could flow onto the floor of the containment building. If that happens, the structure likely will fail, the experts said.
"The containment building at this plant is certainly stronger than that at Chernobyl but a lot less strong than at Three Mile Island, so time will tell," he said.
Peter Bradford, former head of the US Nuclear Regulatory Commission, said that if the cooling attempts fail, "at that point it's a Chernobyl-like situation where you start dumping in sand and cement."
The two worst nuclear accidents on record are the 1986 Chernobyl disaster in Ukraine and the partial core meltdown of the Three Mile Island reactor in the US state of Pennsylvania in 1979.
Another expert said the Japanese accident will rank as one of the three worst in history.
"If it continues, if they don't get control of this and... we go from a partial meltdown of the core to a full meltdown, this will be a complete disaster," Joseph Cirincione, the head of the Ploughshares Fund, said in an interview on CNN.
Cirincione faulted Japanese authorities for providing partial and conflicting information about what was happening at the plant.
Cirincione said the presence of radioactive cesium in the atmosphere after the plant was vented indicated that a partial meltdown was underway.
"That told the operators that the fuel rods had been exposed, that the water level had dropped below the fuel rods and the fuel rods were starting to burn, releasing cesium," he said.
Japan's nuclear safety agency rated the Fukushima accident at four on the International Nuclear Event Scale from 0 to 7, meaning an accident "with local consequences," an official said Sunday.
The Three Mile Island accident was rated five while Chernobyl was a seven.
The government declared an atomic emergency and said tens of thousands of people living within 12 miles (20 kilometers) of the plant should leave after an explosion at the nuclear plant Saturday.
"This is obviously a significant setback for the so-called nuclear renaissance," said Bradford, the former NRC commissioner.
"The image of a nuclear power plant blowing up before your eyes on the television screen is a first."
But a spokesman for the World Nuclear Association said in an interview with CBS News that the threat of a full meltdown is minimal.
"I think that possibility is remote at the best of times and is diminishing by the hour as the fuel gets cooler and generates less heat," said Ian Hore-Lacy, spokesman for the industry organization.
Saturday, March 12, 2011 by CommonDreams.org
Behind the Hydrogen Explosion at the Fukushima Nuclear Plant
by Karl Grossman
The explosion at the Fukushima nuclear power plant is being described as caused by a “hydrogen build-up” The situation harks back to the “hydrogen bubble” that was feared would explode when the Three Mile Island plant in 1979 underwent a partial meltdown.
The hydrogen explosion problem at nuclear power plants involves a story as crazy as can be. As nuts as using nuclear fission to boil water to generate electricity is, the hydrogen problem and its cause cap the lunacy.
Eruption of hydrogen gas as a first reaction in a loss-of-coolant accident has been discussed with great worry in U.S. government and nuclear industry literature for decades.
That is because a highly volatile substance called zirconium was chosen back in the 1940’s and 50’s, when plans were first developed to build nuclear power plants, as the material to be used to make the rods into which radioactive fuel would be loaded.
There are 30,000 to 40,000 rods—composed of twenty tons of zirconium—in an average nuclear power plant. Many other substances were tried, particularly stainless steel, but only zirconium worked well. That’s because zirconium, it was found, allows neutrons from the fuel pellets in the rods to pass freely between the rods and thus a nuclear chain reaction to be sustained.
But there’s a huge problem with zirconium—it is highly volatile and when hot will explode spontaneously upon contact with air, water or steam.
The only other major commercial use of zirconium through the years has been in flashbulbs used in photography. A speck of it, on a flashbulb, ignites to provide a flash of light.
But in a nuclear plant, we’re not talking about specks—but tons and tons of zirconium, put together as a compound called “zircaloy” that clads tens of thousands of fuel rods.
Heat, a great deal of heat, builds up in a very short time with any interruption of coolant flow in a nuclear power plant—the problem at Fukushima after the earthquake that struck Japan.
Zirconium, with the explosive power, pound for pound, of nitroglycerine, will catch fire and explode at a temperature of 2,000 degrees Fahrenheit, well below the 5,000 degree temperature of a meltdown.
Before then, however, zirconium reacts to the heat by drawing oxygen from water and steam and letting off hydrogen, which itself can explode—and is said to have done so at Fukushima.
As a result of such a hydrogen explosion, there is additional heat—bringing the zirconium itself closer and closer to its explosive level.
Whether in addition to being a hydrogen explosion, zirconium also exploded at Fukushima remains to be known.
But what has happened regarding hydrogen at Fukushima, like the “hydrogen bubble” when the Three Mile Island plant in Pennsylvania underwent its near partial meltdown, is no mystery—but precisely what is expected in a loss-of-coolant accident.
It is described in U.S. government and nuclear industry accident studies as a “metal-water” reaction. It’s a reaction, the research has long stated, that can easily trigger a meltdown.
Using tons of a material otherwise used as the speck that explodes in a flashbulb in nuclear power plants —yes, absolutely crazy.
Moreover, in the spent fuel pools usually situated next to nuclear power plants, there are large numbers of additional fuel rods, used ones, disposed of as waste. There must be constant water circulation in the spent fuel pools. In what is labeled a “loss-of-water’ accident in a spent fuel pool, the zirconium cladding of the fuel rods is projected as exploding—sending into the environment the lethal nuclear poisons in a spent fuel pool.
US Experts: 'Chernobyl-Like' Crisis for Japan
WASHINGTON - US nuclear experts warned Saturday that pumping sea water to cool a quake-hit Japanese nuclear reactor was an "act of desperation" that may foreshadow a Chernobyl-like disaster.
Official in protective gear talks to a woman who is from the evacuation area near the Fukushima Daini nuclear plant in Koriyama March 13, 2011. Japan battled to contain a radiation leak at an earthquake-crippled nuclear plant on Sunday, but faced a fresh threat with the failure of the cooling system in a second reactor. REUTERS/Kim Kyung-Hoon Several experts, in a conference call with reporters, also predicted that regardless of the outcome at the Fukushima No. 1 atomic plant crisis, the accident will seriously damage the nuclear power renaissance.
"The situation has become desperate enough that they apparently don't have the capability to deliver fresh water or plain water to cool the reactor and
stabilize it, and now, in an act of desperation, are having to resort to diverting and using sea water," said Robert Alvarez, who works on nuclear disarmament at the Institute for Policy Studies.
"I would describe this measure as a 'Hail Mary' pass," added Alvarez, using American football slang for a final effort to win the game as time expires.
An 8.9 magnitude earthquake that struck Japan on Friday set off the emergency at the plant, which was then hit by an explosion Saturday that prompted an evacuation of the surrounding area.
Workers doused the stricken reactor with sea water to try to avert catastrophe, after the quake knocked out power to the cooling system.
What occurred at the plant was a "station blackout," which is the loss of offsite air-conditioning power combined with the failure of onsite power, in this case diesel generators.
"It is considered to be extremely unlikely but the station blackout has been one of the great concerns for decades," said Ken Bergeron, a physicist who has worked on nuclear reactor accident simulation.
"We're in uncharted territory," he said.
The reactor has been shut down but the concern is the heat in the core, which can melt if it's not cooled. If the core melts through the reactor vessel, Bergeron explained, it could flow onto the floor of the containment building. If that happens, the structure likely will fail, the experts said.
"The containment building at this plant is certainly stronger than that at Chernobyl but a lot less strong than at Three Mile Island, so time will tell," he said.
Peter Bradford, former head of the US Nuclear Regulatory Commission, said that if the cooling attempts fail, "at that point it's a Chernobyl-like situation where you start dumping in sand and cement."
The two worst nuclear accidents on record are the 1986 Chernobyl disaster in Ukraine and the partial core meltdown of the Three Mile Island reactor in the US state of Pennsylvania in 1979.
Another expert said the Japanese accident will rank as one of the three worst in history.
"If it continues, if they don't get control of this and... we go from a partial meltdown of the core to a full meltdown, this will be a complete disaster," Joseph Cirincione, the head of the Ploughshares Fund, said in an interview on CNN.
Cirincione faulted Japanese authorities for providing partial and conflicting information about what was happening at the plant.
Cirincione said the presence of radioactive cesium in the atmosphere after the plant was vented indicated that a partial meltdown was underway.
"That told the operators that the fuel rods had been exposed, that the water level had dropped below the fuel rods and the fuel rods were starting to burn, releasing cesium," he said.
Japan's nuclear safety agency rated the Fukushima accident at four on the International Nuclear Event Scale from 0 to 7, meaning an accident "with local consequences," an official said Sunday.
The Three Mile Island accident was rated five while Chernobyl was a seven.
The government declared an atomic emergency and said tens of thousands of people living within 12 miles (20 kilometers) of the plant should leave after an explosion at the nuclear plant Saturday.
"This is obviously a significant setback for the so-called nuclear renaissance," said Bradford, the former NRC commissioner.
"The image of a nuclear power plant blowing up before your eyes on the television screen is a first."
But a spokesman for the World Nuclear Association said in an interview with CBS News that the threat of a full meltdown is minimal.
"I think that possibility is remote at the best of times and is diminishing by the hour as the fuel gets cooler and generates less heat," said Ian Hore-Lacy, spokesman for the industry organization.
++++++
Saturday, March 12, 2011 by CommonDreams.org
Behind the Hydrogen Explosion at the Fukushima Nuclear Plant
by Karl Grossman
The explosion at the Fukushima nuclear power plant is being described as caused by a “hydrogen build-up” The situation harks back to the “hydrogen bubble” that was feared would explode when the Three Mile Island plant in 1979 underwent a partial meltdown.
The hydrogen explosion problem at nuclear power plants involves a story as crazy as can be. As nuts as using nuclear fission to boil water to generate electricity is, the hydrogen problem and its cause cap the lunacy.
Eruption of hydrogen gas as a first reaction in a loss-of-coolant accident has been discussed with great worry in U.S. government and nuclear industry literature for decades.
That is because a highly volatile substance called zirconium was chosen back in the 1940’s and 50’s, when plans were first developed to build nuclear power plants, as the material to be used to make the rods into which radioactive fuel would be loaded.
There are 30,000 to 40,000 rods—composed of twenty tons of zirconium—in an average nuclear power plant. Many other substances were tried, particularly stainless steel, but only zirconium worked well. That’s because zirconium, it was found, allows neutrons from the fuel pellets in the rods to pass freely between the rods and thus a nuclear chain reaction to be sustained.
But there’s a huge problem with zirconium—it is highly volatile and when hot will explode spontaneously upon contact with air, water or steam.
The only other major commercial use of zirconium through the years has been in flashbulbs used in photography. A speck of it, on a flashbulb, ignites to provide a flash of light.
But in a nuclear plant, we’re not talking about specks—but tons and tons of zirconium, put together as a compound called “zircaloy” that clads tens of thousands of fuel rods.
Heat, a great deal of heat, builds up in a very short time with any interruption of coolant flow in a nuclear power plant—the problem at Fukushima after the earthquake that struck Japan.
Zirconium, with the explosive power, pound for pound, of nitroglycerine, will catch fire and explode at a temperature of 2,000 degrees Fahrenheit, well below the 5,000 degree temperature of a meltdown.
Before then, however, zirconium reacts to the heat by drawing oxygen from water and steam and letting off hydrogen, which itself can explode—and is said to have done so at Fukushima.
As a result of such a hydrogen explosion, there is additional heat—bringing the zirconium itself closer and closer to its explosive level.
Whether in addition to being a hydrogen explosion, zirconium also exploded at Fukushima remains to be known.
But what has happened regarding hydrogen at Fukushima, like the “hydrogen bubble” when the Three Mile Island plant in Pennsylvania underwent its near partial meltdown, is no mystery—but precisely what is expected in a loss-of-coolant accident.
It is described in U.S. government and nuclear industry accident studies as a “metal-water” reaction. It’s a reaction, the research has long stated, that can easily trigger a meltdown.
Using tons of a material otherwise used as the speck that explodes in a flashbulb in nuclear power plants —yes, absolutely crazy.
Moreover, in the spent fuel pools usually situated next to nuclear power plants, there are large numbers of additional fuel rods, used ones, disposed of as waste. There must be constant water circulation in the spent fuel pools. In what is labeled a “loss-of-water’ accident in a spent fuel pool, the zirconium cladding of the fuel rods is projected as exploding—sending into the environment the lethal nuclear poisons in a spent fuel pool.
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