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168188
Tue, 03/15/2011 - 05:27
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Meltdown May Have Occurred at Another Fukushima Reactor
(Update 3)
Tokyo, March 14 (Jiji Press)--Tokyo Electric Power Co. <9501> said Monday that the No. 2 reactor of its quake-hit Fukushima No. 1 nuclear power plant may have experienced a meltdown.
The fuel rods of the reactor, each of which is 4 meters long, became fully exposed to air in the day's evening and again late at night because of a substantial drop in the amount of cooling water in the reactor, according to the firm.
According to Tokyo Electric Power and the Nuclear and Industrial Safety Agency of the Ministry of Economy, Trade and Industry, the cooling system for the No. 2 reactor stopped functioning on Monday afternoon.
The level of cooling water, which was some 3.9 meters above the top of the fuel rods in as of 9 a.m. Monday (midnight Sunday GMT), started to fall in the evening.
Tokyo Electric Power tried to pump sea water into the reactor in response to the falling water level inside. But the pumps stopped as they ran out of fuel, the company officials said, explaining the reason for the entire loss of cooling water.
Around 6:30 p.m., the fuel rods were fully exposed to air, according to Tokyo Electric Power officials.
For about two hours after that, the reactor appeared to have kept operating without any cooling water, and this might have caused the fuel rods to melt, the officials said.
Later, the pumps were refueled, and the work to pour sea water into the reactor was resumed. As a result, the water level rose back to around the half of the fuel rods as of 9:34 p.m., the officials said.
But around 11 p.m., the valves of the reactor's container closed and pressure inside increased, preventing the work to pump sea water into the reactor. The cooling water level thus dropped, causing the fuel rods to be fully exposed to air again, the officials said.
Shortly past midnight Monday, the valves of the outer vessel of the reactor were opened to release the pressure, according to the officials.
At 9:37 p.m. Monday, the company detected radiation of 3,130 microsieverts per hour, the highest amount found after the earthquake, near the main gate of the nuclear plant premises, according to the officials.
Shortly past 10 p.m., radiation of 9.4 microsieverts per hour, some 260 times the normal level, was detected in areas near the company's Fukushima No. 2 nuclear power plant, which is some 10 kilometers south of the No. 1 plant, the officials said.
At the Fukushima No. 1 plant, the No. 1 reactor is likely to have experienced a partial meltdown on Saturday, the first time this has ever happened in Japan.
Chief Cabinet Secretary Yukio Edano told a news conference that it is highly likely that partial meltdowns have occurred at the plant's No. 1, 2 and 3 reactors, which were operating when the 9.0-magnitude earthquake struck the Tohoku northeastern Japan region, including Fukushima Prefecture, on Friday. The plant's three other reactors--No. 4, 5 and 6--are undergoing regular inspections.
Hidehiko Nishiyama, a senior official at the Industry Ministry, told a separate news conference that it is clear the government's quake-resistance standards for nuclear reactors are insufficient.
The latest reactor incident came after a hydrogen explosion happened at the No. 3 reactor of the same nuclear plant Monday morning, injuring 11 including four Self-Defense Forces troops.
Due to the explosion, a 23-year-old male employee of Tokyo Electric Power was exposed to radiation. Five other people got radioactive substance on them, and decontamination work was done for them, the company said.
The explosion was similar to the one that happened at the No. 1 reactor on Saturday.
Following the latest blast, work to evacuate residents who are still within a 20-kilometer radius of the power plant was resumed.
Tokyo Electric Power also said that the No. 1 and No. 2 reactors at the Fukushima No. 2 nuclear plant were no longer in dangerous states as the temperatures inside the reactors fell below 100 degrees Celsius.
Tokyo, March 14 (Jiji Press)--Tokyo Electric Power Co. <9501> said Monday that the No. 2 reactor of its quake-hit Fukushima No. 1 nuclear power plant may have experienced a meltdown.
The fuel rods of the reactor, each of which is 4 meters long, became fully exposed to air in the day's evening and again late at night because of a substantial drop in the amount of cooling water in the reactor, according to the firm.
According to Tokyo Electric Power and the Nuclear and Industrial Safety Agency of the Ministry of Economy, Trade and Industry, the cooling system for the No. 2 reactor stopped functioning on Monday afternoon.
The level of cooling water, which was some 3.9 meters above the top of the fuel rods in as of 9 a.m. Monday (midnight Sunday GMT), started to fall in the evening.
Tokyo Electric Power tried to pump sea water into the reactor in response to the falling water level inside. But the pumps stopped as they ran out of fuel, the company officials said, explaining the reason for the entire loss of cooling water.
Around 6:30 p.m., the fuel rods were fully exposed to air, according to Tokyo Electric Power officials.
For about two hours after that, the reactor appeared to have kept operating without any cooling water, and this might have caused the fuel rods to melt, the officials said.
Later, the pumps were refueled, and the work to pour sea water into the reactor was resumed. As a result, the water level rose back to around the half of the fuel rods as of 9:34 p.m., the officials said.
But around 11 p.m., the valves of the reactor's container closed and pressure inside increased, preventing the work to pump sea water into the reactor. The cooling water level thus dropped, causing the fuel rods to be fully exposed to air again, the officials said.
Shortly past midnight Monday, the valves of the outer vessel of the reactor were opened to release the pressure, according to the officials.
At 9:37 p.m. Monday, the company detected radiation of 3,130 microsieverts per hour, the highest amount found after the earthquake, near the main gate of the nuclear plant premises, according to the officials.
Shortly past 10 p.m., radiation of 9.4 microsieverts per hour, some 260 times the normal level, was detected in areas near the company's Fukushima No. 2 nuclear power plant, which is some 10 kilometers south of the No. 1 plant, the officials said.
At the Fukushima No. 1 plant, the No. 1 reactor is likely to have experienced a partial meltdown on Saturday, the first time this has ever happened in Japan.
Chief Cabinet Secretary Yukio Edano told a news conference that it is highly likely that partial meltdowns have occurred at the plant's No. 1, 2 and 3 reactors, which were operating when the 9.0-magnitude earthquake struck the Tohoku northeastern Japan region, including Fukushima Prefecture, on Friday. The plant's three other reactors--No. 4, 5 and 6--are undergoing regular inspections.
Hidehiko Nishiyama, a senior official at the Industry Ministry, told a separate news conference that it is clear the government's quake-resistance standards for nuclear reactors are insufficient.
The latest reactor incident came after a hydrogen explosion happened at the No. 3 reactor of the same nuclear plant Monday morning, injuring 11 including four Self-Defense Forces troops.
Due to the explosion, a 23-year-old male employee of Tokyo Electric Power was exposed to radiation. Five other people got radioactive substance on them, and decontamination work was done for them, the company said.
The explosion was similar to the one that happened at the No. 1 reactor on Saturday.
Following the latest blast, work to evacuate residents who are still within a 20-kilometer radius of the power plant was resumed.
Tokyo Electric Power also said that the No. 1 and No. 2 reactors at the Fukushima No. 2 nuclear plant were no longer in dangerous states as the temperatures inside the reactors fell below 100 degrees Celsius.
