A evacuation radius of 20km has been set up around the stricken 40-year-old Daiichi 1 reactor plant in Fukushima prefecture. TV footage showed vapour rising from the plant, 240km north of Tokyo.
Here are some facts about resource-scarce Japan's growing use of nuclear energy:
- Japan needs to import some 80 percent of its energy requirements.
- The country's first commercial nuclear power reactor began operating in mid-1966, and nuclear energy has been a national strategic priority since 1973, when the oil shock prompted a turn to nuclear energy in a bigger way, although the country already had five nuclear reactors. Japan adopted a closed fuel cycle to gain the maximum benefit from imported uranium.
- Japan's 54 reactors provide some 30 percent of the country's electricity today, and this is expected to increase to at least 40 percent by 2017, and 50 percent by 2030. Japan has a full fuel cycle set-up, including enrichment and reprocessing of used-fuel for recycling.
- In 2008, Japan generated 1,085 billion kWh gross power, of which 30 percent was from coal, 25 percent from gas, 24 percent from nuclear, 11 percent from oil, and 7.5 percent from hydropower, though 8 GWe of nuclear capacity was shut down for checks following an earthquake in mid-2007. Per capita consumption is about 7900 kWh/yr.
- Japan's existing 54 reactors have a total of 46,102 MWe (net) on line, with two (2,756 MWe) under construction and 12 (16,532 MWe) planned.
This would lead to nuclear energy contributing about 60 percent of primary energy in 2100 (compared with 10 percent now), 10 percent from renewables (now 5 percent) and 30 percent fossil fuels (now 85 percent).
That implies nuclear power would contribute 51 percent of the emission reduction - 38 percent from power generation and 13 percent from hydrogen production and process heat.
- Reuters
Explosion in Japan nuke plant, meltdown feared
Radiation leaked from an unstable Japanese nuclear reactor north of Tokyo today after an explosion blew the roof off the facility in the wake of a massive earthquake.
The developments raised fears of a disastrous meltdown at the plant, which was damaged by yesterday's 8.9-magnitude earthquake, the strongest ever recorded in Japan.
The developments raised fears of a disastrous meltdown at the plant, which was damaged by yesterday's 8.9-magnitude earthquake, the strongest ever recorded in Japan.
"We are looking into the cause and the situation and we'll
make that public when we have further information," said chief cabinet secretary Yukio Edano.
make that public when we have further information," said chief cabinet secretary Yukio Edano.
T
elevision footage showed smoke billowing from the quake-hit atomic plant Fukushima No 1, about 250km northeast of Tokyo, at about 4pm Malaysian time.
State TV station NHK reported that several workers were injured in the blast and that the walls and roof of the quake-damaged nuclear plant had been destroyed.
The Japanese TV channel warned residents living near the nuclear plant to stay indoors. Radioactivity at around the nuclear plant is 20 times of normal level.
elevision footage showed smoke billowing from the quake-hit atomic plant Fukushima No 1, about 250km northeast of Tokyo, at about 4pm Malaysian time.State TV station NHK reported that several workers were injured in the blast and that the walls and roof of the quake-damaged nuclear plant had been destroyed.
The Japanese TV channel warned residents living near the nuclear plant to stay indoors. Radioactivity at around the nuclear plant is 20 times of normal level.
The government said the Tokyo Fire Department has sent its 'hyper rescue team' to the damaged nuclear plant. It has expanded the evacuation area around the nuclear reactor to a 20km radius from 10km.
Japan's Kyodo News agency however said that the hourly radiation level at the damaged nuclear power plant in Fukushima Prefecture 'matches the allowable annual dose.'
Premier Naoto Kan has urged calm among people living near the affected power plant.
Iodine to be distributed
Meanwhile, Japanese authorities have told the UN atomic watchdog they are making preparations to distribute iodine to people living near nuclear power plants.
Iodine can be used to help protect the body from radioactive exposure. However, the government insisted that radiation levels were low.
Japan's Jiji news agency later said three workers suffered radiation exposure near the Fukushima nuclear plant.
The International Atomic Energy Agency (IAEA), the UN nuclear body, said Japanese authorities had informed it of the explosion and that they were "assessing the condition of the reactor core".
Japan expanded the evacuation zone around the plant, Fukushima Daiichi, and also that of the nearby Fukushima Daini nuclear power plant.
"The authorities also say they are making preparations to distribute iodine to residents in the area of both the plants," the IAEA said in a statement.
Iodine can be used to help protect the body from radioactive exposure. However, the government insisted that radiation levels were low.
Japan's Jiji news agency later said three workers suffered radiation exposure near the Fukushima nuclear plant.The International Atomic Energy Agency (IAEA), the UN nuclear body, said Japanese authorities had informed it of the explosion and that they were "assessing the condition of the reactor core".
Japan expanded the evacuation zone around the plant, Fukushima Daiichi, and also that of the nearby Fukushima Daini nuclear power plant.
"The authorities also say they are making preparations to distribute iodine to residents in the area of both the plants," the IAEA said in a statement.
Desperate attempt to cool down reactor
The blast came as plant operator Tokyo Electric Power Co (Tepco) worked desperately to reduce pressures in the core of the reactor that - if not contained - could lead to a release of radiation into the atmosphere.
"An unchecked rise in temperature could cause the core to essentially turn into a molten mass that could burn through the reactor vessel," risk information service Stratfor said in a report.
"This may lead to a release of an unchecked amount of radiation into the containment building that surrounds the reactor."
"An unchecked rise in temperature could cause the core to essentially turn into a molten mass that could burn through the reactor vessel," risk information service Stratfor said in a report.
"This may lead to a release of an unchecked amount of radiation into the containment building that surrounds the reactor."
According to experts, nuclear reactors remain tremendously hot for at least two days even after they have been shut down.
"Reactors are not like your car that you can turn off and walk away. They're going to continue generating a great amount of heat until the core is disassembled.
"Without cooling water, then you stand a real chance of a meltdown of core that could result in a large release of radiation, potentially," said Ron Chesser, director for the Center of Environmental Radiation Studies at Texas Tech University.
Chesser was the first American scientist allowed inside the exclusion zone in 1992 in Ukraine following the Chernobyl disaster.
Nuclear fuel rods briefly exposed
Officials at the plant had earlier reported that part of the reactor core was exposed to air for a brief moment and that they were attempting to raise the water level to continue cooling the reactor with the help from a fire engine's pump.
Reactor cooling systems failed at two plants after yesterday's record 8.9-magnitude earthquake hit, unleashing a terrifying 10-metre high wave that tore through coastal towns and cities, destroying all in its path.
Kyodo News agency said radioactive caesium had been detected near Fukushima No 1, one of the quake-hit plants.
Reactor cooling systems failed at two plants after yesterday's record 8.9-magnitude earthquake hit, unleashing a terrifying 10-metre high wave that tore through coastal towns and cities, destroying all in its path.
Kyodo News agency said radioactive caesium had been detected near Fukushima No 1, one of the quake-hit plants.The cooling system of the plant was damaged in the massive earthquake that struck the region 24 hours earlier, leaving authorities scrambling to fix the problem and evacuate more than 45,000 residents within a 10-kilometre radius.
Thousands were also evacuated from near a second plant, Fukushima No 2, which also suffered damage to its cooling system.
The atomic emergency came as the country struggled to assess the full extent of the devastation wreaked by the massive tsunami, which was unleashed by the strongest quake ever recorded in Japan.
The towering wall of water pulverised the northeastern city of Sendai, where police reportedly said 200-300 bodies had been found on the coast.
Thousands were also evacuated from near a second plant, Fukushima No 2, which also suffered damage to its cooling system.
The atomic emergency came as the country struggled to assess the full extent of the devastation wreaked by the massive tsunami, which was unleashed by the strongest quake ever recorded in Japan.
The towering wall of water pulverised the northeastern city of Sendai, where police reportedly said 200-300 bodies had been found on the coast.
Many shops are closed
Along Japan's northeast coast, rescue workers searched through the rubble of destroyed buildings, cars and boats, looking for survivors in hardest-hit areas such as the city of Sendai, 300km northeast of Tokyo.
Dazed residents hoarded water and huddled in makeshift shelters in near-freezing temperatures. Aerial footage showed buildings and trains strewn over mudflats like children's toys.
"All the shops are closed, this is one of the few still open. I came to buy and stock up on diapers, drinking water and food," Kunio Iwatsuki, 68, told Reuters in Mito city, where residents queued outside a damaged supermarket for supplies.
Across the coastline, survivors clambered over nearly impassable roads. In Iwanuma, not far from Sendai, people spelled S.O.S. out on the roof of a hospital surrounded by water, one of many desperate scenes.
The earthquake and tsunami, and now the radiation leak, present Japan's government with its biggest challenge in a generation.
The explosion at Chernobyl's nuclear plant's fourth reactor in 1986 sent thousands of tonnes of toxic nuclear dust billowing across the Ukraine, Russia and Belarus. It was the worst civil
nuclear disaster.
Nuclear power company has rocky past
The blast at the Japanese nuclear facility came as plant operator Tepco worked desperately to reduce pressures in the core of the reactor.
The company has had a rocky past in an industry plagued by scandal. 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.
NHK television and Jiji news agency said the outer structure of the reactor building that houses the reactor appeared to have blown off, but nuclear experts said this did not necessarily mean the nuclear reactor had been breached.
Earlier the operator released what it said was a tiny amount of radioactive steam to reduce the pressure and the danger was minimal because tens of thousands of people had already been
evacuated from the vicinity.
Dazed residents hoarded water and huddled in makeshift shelters in near-freezing temperatures. Aerial footage showed buildings and trains strewn over mudflats like children's toys.
"All the shops are closed, this is one of the few still open. I came to buy and stock up on diapers, drinking water and food," Kunio Iwatsuki, 68, told Reuters in Mito city, where residents queued outside a damaged supermarket for supplies.Across the coastline, survivors clambered over nearly impassable roads. In Iwanuma, not far from Sendai, people spelled S.O.S. out on the roof of a hospital surrounded by water, one of many desperate scenes.
The earthquake and tsunami, and now the radiation leak, present Japan's government with its biggest challenge in a generation.
The explosion at Chernobyl's nuclear plant's fourth reactor in 1986 sent thousands of tonnes of toxic nuclear dust billowing across the Ukraine, Russia and Belarus. It was the worst civil
nuclear disaster.
Nuclear power company has rocky past
The blast at the Japanese nuclear facility came as plant operator Tepco worked desperately to reduce pressures in the core of the reactor.
The company has had a rocky past in an industry plagued by scandal. 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.
NHK television and Jiji news agency said the outer structure of the reactor building that houses the reactor appeared to have blown off, but nuclear experts said this did not necessarily mean the nuclear reactor had been breached.
Earlier the operator released what it said was a tiny amount of radioactive steam to reduce the pressure and the danger was minimal because tens of thousands of people had already been
evacuated from the vicinity.
Nuclear experts: Major disaster unlikely
Here are comments from experts about what might have happened in Fukushima and the possibility of a Chernobyl-type disaster.
Professor Paddy Regan, nuclear physicist from Britain's Surrey University
"It looks as if the coolant pumps had initially stopped working. They shut down automatically when the reactor shuts down, but there is a backup system running off a diesel generator - it looks as though that's the bit that failed.
“As a result there is no way of pumping heat out of the reactor, so it has to cool naturally. If the reactor gets too hot, in principle this means the fuel rods can melt - but it looks unlikely this has happened to any great extent in this case.
"To reduce the pressure, you would have to release some steam into the atmosphere from the system. In that steam, there will be small but measurable amounts of radioactive nitrogen - nitrogen 16 (produced when neutrons hit water). This remains radioactive for only about 5 seconds, after which it decays to natural oxygen.
"But if any of the fuel rods have been compromised, there would be evidence of a small amount of other radioisotopes in the atmosphere called fission fragments (radio-caesium and radio-iodine).
"The amount that you measure would tell you to what degree the fuel rods have been compromised. Scientists in Japan should be able to establish this very quickly using gamma ray spectroscopy as the isotopes have characteristic decay signatures. Current reports seem consistent with a small leak to relieve pressure."
"But we still need to establish the cause and exact location of the explosion, which is a separate issue. So far it looks like it's not the reactor core that's affected which would be good news.
"We must remember that there are 55 reactors in Japan and this was a huge earthquake, and as a test of the resilience and robustness of nuclear plants it seems they have withstood the
effects very well."
“As a result there is no way of pumping heat out of the reactor, so it has to cool naturally. If the reactor gets too hot, in principle this means the fuel rods can melt - but it looks unlikely this has happened to any great extent in this case.
"To reduce the pressure, you would have to release some steam into the atmosphere from the system. In that steam, there will be small but measurable amounts of radioactive nitrogen - nitrogen 16 (produced when neutrons hit water). This remains radioactive for only about 5 seconds, after which it decays to natural oxygen.
"But if any of the fuel rods have been compromised, there would be evidence of a small amount of other radioisotopes in the atmosphere called fission fragments (radio-caesium and radio-iodine).
"The amount that you measure would tell you to what degree the fuel rods have been compromised. Scientists in Japan should be able to establish this very quickly using gamma ray spectroscopy as the isotopes have characteristic decay signatures. Current reports seem consistent with a small leak to relieve pressure."
"But we still need to establish the cause and exact location of the explosion, which is a separate issue. So far it looks like it's not the reactor core that's affected which would be good news.
"We must remember that there are 55 reactors in Japan and this was a huge earthquake, and as a test of the resilience and robustness of nuclear plants it seems they have withstood the
effects very well."
Timothy Abram, professor of nuclear fuel technology at Britain's Manchester University
“By sampling the air around the station, you'd be able to tell how much radioactivity has been released. The thing they'll be looking for more than anything is whether there's any evidence of the fuel actually degrading," he told Reuters.
"If the fuel is substantially intact, then there'll be a much, much lower release of radioactivity and the explosion that's happened might be just due to a build-up of steam in the reactor circuit.
"The most probable (cause of the explosion) is the coolant, particularly if it's water, can overheat and turn to steam more rapidly than it was designed to cope with."
He said it was unlikely it would develop into anything more serious, but this would depend on the integrity of the fuel, which contains nearly all the radioactivity of the plant. He said he thought it would be "pretty unlikely" that the fuel itself had been significantly damaged.
He said if this did occur, some radioactive material might be released into the primary circuit, which in turn might be vented into the containment building to release the pressure.
"Even the worse case scenario from there is the pressure in the containment building itself builds up to dangerous levels and has to be released," he said.
"Consequently you are releasing pressure from in the containment building, some of which contains radioactivity, out into the environment. There are a lot of ifs in that chain of events."
Valeriy Hlyhalo, deputy director-general of the Chernobyl Nuclear safety centre
"The explosion at No 1 generating set of the Fukushima nuclear plant in Japan, which took place today, will not be a repetition of the Chernobyl nuclear disaster," Interfax quoted the Ukrainian expert as saying.
He said that the Japanese nuclear power plants use reactors of a totally different design to Chernobyl's.
“Japan has modern-type reactors. All fission products should be isolated by the confinement (the reactor's protection shell). Only gas emission is possible."
Hlyhalo said that Japanese nuclear power plants are earthquake resistant.
"Apart from that, these reactors are designed to work at a high seismicity zone, although what has happened is beyond the impact the plants were designed to withstand. Therefore, the consequences should not be as serious as after the Chernobyl nuclear disaster."
Ian Hore-Lacy of the World Nuclear Association, an industry body representing 180 companies in the nuclear sector
“It is obviously an hydrogen explosion ... due to hydrogen igniting. If the hydrogen has ignited, then it is gone, it doesn't pose any further threat."
"The whole situation is quite serious but the actual hydrogen explosion doesn't add a great deal to it."
He said it was "most unlikely to be a major disaster" and he also did not believe there would be a full fuel meltdown.
"That would have been much more likely early yesterday in the European time. We are now 24 hours into the situation and the fuel has cooled a lot in that time and the likelihood of meltdown at this stage I would think would be very, very small."
Robin Grimes, professor of materials physics at Imperial College London
"It does seem as if the back-up generators although they started initially to work, then failed," Grimes, an expert in radiation damage told BBC TV.
"So it means slowly the heat and the pressure built up in this reactor. One of the things that might just have happened is a large release of that pressure. If it's that then we're not in such bad circumstances.
"Despite the damage to the outer structure, as long as that steel inner vessel remains intact, then the vast majority of the radiation will be contained.
"At the moment it does seem that they are still contained and it's a release of significant steam pressure that's caused this explosion. The key will be the monitoring of those radiation levels."
“By sampling the air around the station, you'd be able to tell how much radioactivity has been released. The thing they'll be looking for more than anything is whether there's any evidence of the fuel actually degrading," he told Reuters.
"If the fuel is substantially intact, then there'll be a much, much lower release of radioactivity and the explosion that's happened might be just due to a build-up of steam in the reactor circuit.
"The most probable (cause of the explosion) is the coolant, particularly if it's water, can overheat and turn to steam more rapidly than it was designed to cope with."He said it was unlikely it would develop into anything more serious, but this would depend on the integrity of the fuel, which contains nearly all the radioactivity of the plant. He said he thought it would be "pretty unlikely" that the fuel itself had been significantly damaged.
He said if this did occur, some radioactive material might be released into the primary circuit, which in turn might be vented into the containment building to release the pressure.
"Even the worse case scenario from there is the pressure in the containment building itself builds up to dangerous levels and has to be released," he said.
"Consequently you are releasing pressure from in the containment building, some of which contains radioactivity, out into the environment. There are a lot of ifs in that chain of events."
Valeriy Hlyhalo, deputy director-general of the Chernobyl Nuclear safety centre
"The explosion at No 1 generating set of the Fukushima nuclear plant in Japan, which took place today, will not be a repetition of the Chernobyl nuclear disaster," Interfax quoted the Ukrainian expert as saying.
He said that the Japanese nuclear power plants use reactors of a totally different design to Chernobyl's.“Japan has modern-type reactors. All fission products should be isolated by the confinement (the reactor's protection shell). Only gas emission is possible."
Hlyhalo said that Japanese nuclear power plants are earthquake resistant.
"Apart from that, these reactors are designed to work at a high seismicity zone, although what has happened is beyond the impact the plants were designed to withstand. Therefore, the consequences should not be as serious as after the Chernobyl nuclear disaster."
Ian Hore-Lacy of the World Nuclear Association, an industry body representing 180 companies in the nuclear sector
“It is obviously an hydrogen explosion ... due to hydrogen igniting. If the hydrogen has ignited, then it is gone, it doesn't pose any further threat."
"The whole situation is quite serious but the actual hydrogen explosion doesn't add a great deal to it."
He said it was "most unlikely to be a major disaster" and he also did not believe there would be a full fuel meltdown.
"That would have been much more likely early yesterday in the European time. We are now 24 hours into the situation and the fuel has cooled a lot in that time and the likelihood of meltdown at this stage I would think would be very, very small."
Robin Grimes, professor of materials physics at Imperial College London
"It does seem as if the back-up generators although they started initially to work, then failed," Grimes, an expert in radiation damage told BBC TV.
"So it means slowly the heat and the pressure built up in this reactor. One of the things that might just have happened is a large release of that pressure. If it's that then we're not in such bad circumstances.
"Despite the damage to the outer structure, as long as that steel inner vessel remains intact, then the vast majority of the radiation will be contained.
"At the moment it does seem that they are still contained and it's a release of significant steam pressure that's caused this explosion. The key will be the monitoring of those radiation levels."
- Reuters