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by 82_28 » Sat Mar 12, 2011 6:58 am
by justdrew » Sat Mar 12, 2011 7:03 am
by 82_28 » Sat Mar 12, 2011 7:12 am
by justdrew » Sat Mar 12, 2011 7:19 am
82_28 wrote:#
1110: An attempt to explain the risk to the Fukushima nuclear plants following the earthquake: The plants are designed to shut down automatically, which halts the main nuclear fission reaction, but there is a residual amount of intense heat within the system. Back-up generators should kick in to power the cooling mechanisms needed to dissipate that heat - but if they fail, as appears to have happened here, temperatures rise. If this isn't stopped, the reactor vessel itself could eventually melt and leak.
by seemslikeadream » Sat Mar 12, 2011 8:45 am
TOKYO (MarketWatch) --- Smoke or steam was seen around Tokyo Electric Power Co.'s Fukushima Daiichi nuclear power plant Saturday, according to Japanese broadcaster NHK. Several worders were reported injured at the plant, NHK said, adding that the exact cause of the emission was unknown. NHK reported an explosion was heard about 10 minutes before the white cloud appeared around the plant. Japanese media earlier Saturday warned that a meltdown was possible or may be already occurring at plant, after Friday's 8.9-magnitude earthquake and tsunami struck Japan's northeast coast and damaged the reactor's cooling system.
1016: The BBC's environment correspondent Roger Harrabin says he understands the blast at the nuclear plant may have been caused by a hydrogen explosion - also one of the possibilities laid out by Walt Patterson of Chatham House. "If nuclear fuel rods overheat and then come into contact with water, this produces a large amount of highly-flammable hydrogen gas which can then ignite," our correspondent says.
1011: More from Walt Patterson of Chatham House. He says the presence of the radioactive caesium in the surrounding area does not pose a huge threat to public health in the immediate aftermath of the explosion. "What would be serious is if there was an explosion or fire that lifted this stuff high in the air, meaning it could get carried over a wide area."
1009: "This is starting to look a lot like Chernobyl" Walt Patterson, an associate fellow with Chatham House, has told the BBC after seeing pictures of the explosion at the Fukushima-Daiichi nuclear plant. "The nuclear agency says that they have detected caesium and iodine outside the unit, which certainly indicates fuel melting at the very least," he says. "Once you have melting fuel coming into contact with water, that would almost certainly be the cause of the explosion."
A meltdown occurs when the control rods fail to contain the neutron emission and the heat levels inside the reactor thus rise to a point that the fuel itself melts, generally temperatures in excess of 1,000 degrees Fahrenheit, causing uncontrolled radiation-generating reactions and making approaching the reactor incredibly hazardous. A meltdown does not necessarily mean a nuclear disaster. As long as the reactor core, which is specifically designed to contain high levels of heat, pressure and radiation, remains intact, the melted fuel can be dealt with. If the core breaches but the containment facility built around the core remains intact, the melted fuel can still be dealt with — typically entombed within specialized concrete — but the cost and difficulty of such containment increases exponentially.
However, the earthquake in Japan, in addition to damaging the ability of the control rods to regulate the fuel — and the reactor’s coolant system — appears to have damaged the containment facility, and the explosion almost certainly did.
At this point, events in Japan bear many similarities to the 1986 Chernobyl disaster. Reports indicate that up to 1.5 meters (4.9 feet) of the reactor fuel was exposed. The reactor fuel appears to have at least partially melted, and the subsequent explosion has shattered the walls and roof of the containment vessel — and likely the remaining useful parts of the control and coolant systems.
And so now the question is simple: Did the floor of the containment vessel crack? If not, the situation can still be salvaged by somehow re-containing the nuclear core. But if the floor has cracked, it is highly likely that the melting fuel will burn through the floor of the containment system and enter the ground. This has never happened before but has always been the nightmare scenario for a nuclear power event — in this scenario, containment goes from being merely dangerous, time consuming and expensive to nearly impossible.
by seemslikeadream » Sat Mar 12, 2011 9:03 am
Japan's nuclear power operator has chequered past
Sat Mar 12, 2011 10:11am GMT
SINGAPORE, March 12 (Reuters) - The company at the centre of a nuclear reactor crisis following the biggest earthquake in Japan's recorded history has had a rocky past in an industry plagued by scandal.
The Japanese government said on Saturday that there had been radiation leakage at Tokyo Electric Power's (TEPCO) Fukushima Daiichi plant following an explosion there.
The blast came as TEPCO was working desperately to reduce pressures in the core of a reactor at the 40-year-old plant, which lies 240 km (150 miles) north of Tokyo.
In 2002, the president of the country's largest power utility was forced to resign along with four other senior executives, taking responsibility for suspected falsification of nuclear plant safety records.
The company was suspected of 29 cases involving falsified repair records at nuclear reactors. It had to stop operations at five reactors, including the two damaged in the latest tremor, for safety inspections.
A few years later it ran into trouble again over accusations of falsifying data.
In late 2006, the government ordered TEPCO to check past data after it reported that it had found falsification of coolant water temperatures at its Fukushima Daiichi plant in 1985 and 1988, and that the tweaked data was used in mandatory inspections at the plant, which were completed in October 2005.
And in 2007, TEPCO reported that it had found more past data falsifications, though this time it did not have to close any of its plants. (Writing by Jonathan Thatcher; Editing by John Chalmers; jonathan.thatcher@thomsonreuters.com
by seemslikeadream » Sat Mar 12, 2011 10:31 am
by seemslikeadream » Sat Mar 12, 2011 11:36 am
Red Alert: Nuclear Meltdown at Quake-Damaged Japanese Plant
March 12, 2011 | 0827 GMT
A March 12 explosion at the earthquake-damaged Fukushima Daiichi nuclear power plant in Okuma, Japan, appears to have caused a reactor meltdown.
The key piece of technology in a nuclear reactor is the control rods. Nuclear fuel generates neutrons; controlling the flow and production rate of these neutrons is what generates heat, and from the heat, electricity. Control rods absorb neutrons — the rods slide in and out of the fuel mass to regulate neutron emission, and with it, heat and electricity generation.
A meltdown occurs when the control rods fail to contain the neutron emission and the heat levels inside the reactor thus rise to a point that the fuel itself melts, generally temperatures in excess of 1,000 degrees Fahrenheit, causing uncontrolled radiation-generating reactions and making approaching the reactor incredibly hazardous. A meltdown does not necessarily mean a nuclear disaster. As long as the reactor core, which is specifically designed to contain high levels of heat, pressure and radiation, remains intact, the melted fuel can be dealt with. If the core breaches but the containment facility built around the core remains intact, the melted fuel can still be dealt with — typically entombed within specialized concrete — but the cost and difficulty of such containment increases exponentially.
However, the earthquake in Japan, in addition to damaging the ability of the control rods to regulate the fuel — and the reactor’s coolant system — appears to have damaged the containment facility, and the explosion almost certainly did. There have been reports of “white smoke,” perhaps burning concrete, coming from the scene of the explosion, indicating a containment breach and the almost certain escape of significant amounts of radiation.
At this point, events in Japan bear many similarities to the 1986 Chernobyl disaster. Reports indicate that up to 1.5 meters (4.9 feet) of the reactor fuel was exposed. The reactor fuel appears to have at least partially melted, and the subsequent explosion has shattered the walls and roof of the containment vessel — and likely the remaining useful parts of the control and coolant systems.
And so now the question is simple: Did the floor of the containment vessel crack? If not, the situation can still be salvaged by somehow re-containing the nuclear core. But if the floor has cracked, it is highly likely that the melting fuel will burn through the floor of the containment system and enter the ground. This has never happened before but has always been the nightmare scenario for a nuclear power event — in this scenario, containment goes from being merely dangerous, time consuming and expensive to nearly impossible.
Radiation exposure for the average individual is 620 millirems per year, split about evenly between manmade and natural sources. The firefighters who served at the Chernobyl plant were exposed to between 80,000 and 1.6 million millirems. The Nuclear Regulatory Commission estimates that exposure to 375,000 to 500,000 millirems would be sufficient to cause death within three months for half of those exposed. A 30-kilometer-radius (19 miles) no-go zone remains at Chernobyl to this day. Japan’s troubled reactor site is about 300 kilometers from Tokyo.
The latest report from the damaged power plant indicated that exposure rates outside the plant were at about 620 millirems per hour, though it is not clear whether that report came before or after the reactor’s containment structure exploded.
Read more: Red Alert: Nuclear Meltdown at Quake-Damaged Japanese Plant | STRATFOR
by seemslikeadream » Sat Mar 12, 2011 2:13 pm
Japan earthquake: Officials say nuclear catastrophe averted
Fears of a nuclear meltdown in Japan have subsided after a reactor that was damaged in Friday’s devastating earthquake reportedly emerged intact from an explosion.
Officials in protective gear check for signs of radiation on children who are from the evacuation area near the Fukushima Daini nuclear plant in Koriyama, Saturday March 12. Fears of a nuclear meltdown subsided after a reactor that was damaged in Friday’s devastating earthquake reportedly emerged intact from an explosion.
Kim Kyung-Hoon/Reuters
by norton ash » Sat Mar 12, 2011 2:18 pm
seemslikeadream wrote:Do ya believe it?Japan earthquake: Officials say nuclear catastrophe averted
Fears of a nuclear meltdown in Japan have subsided after a reactor that was damaged in Friday’s devastating earthquake reportedly emerged intact from an explosion.
Officials in protective gear check for signs of radiation on children who are from the evacuation area near the Fukushima Daini nuclear plant in Koriyama, Saturday March 12. Fears of a nuclear meltdown subsided after a reactor that was damaged in Friday’s devastating earthquake reportedly emerged intact from an explosion.
Kim Kyung-Hoon/Reuters
by JackRiddler » Sat Mar 12, 2011 2:39 pm
And so now the question is simple: Did the floor of the containment vessel crack? If not, the situation can still be salvaged by somehow re-containing the nuclear core. But if the floor has cracked, it is highly likely that the melting fuel will burn through the floor of the containment system and enter the ground.
by justdrew » Sat Mar 12, 2011 2:43 pm
by Peachtree Pam » Sat Mar 12, 2011 3:10 pm
by barracuda » Sat Mar 12, 2011 3:13 pm
by Peachtree Pam » Sat Mar 12, 2011 3:19 pm
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