Tokyo Electric disposing of low radioactive water in Pacific
Apr. 5, 2011
Tokyo Electric Power Co. on Monday took the unprecedented measure of dumping 10,000 tons of low-level radioactive water in the Pacific Ocean from a facility at its crippled Fukushima Daiichi nuclear power complex to make room for the storage of more highly contaminated water, which is hampering restoration work at the plant.
With the total amount of water to reach 11,500 tons, including contaminated groundwater from near the No. 5 and No. 6 reactors, the government said the disposal was unavoidable in order to secure safety. The level of radioactive substances in the water is up to 500 times the legal limit permitted for release in the environment.
The government's nuclear agency said the disposal will pose ''no major health risk'' and experts say that the radioactive materials are likely to be diluted in the sea, but it remains uncertain how the marine environment will be affected when taking into account the impact of highly radioactive water already leaking into the sea from the plant located on the coast of Fukushima Prefecture.
The utility known as TEPCO used colored powder Monday morning to determine how the highly radioactive water, believed to originate from the No. 2 reactor, made its way into the sea. But the Nuclear and Industrial Safety Agency said that it was not able to confirm the route of flow.
In announcing the decision to dispose of the low-level radioactive water, top government spokesman Yukio Edano said, ''We've placed priority on not letting the highly radioactive water flow into the sea.''
Massive tsunami waves that hit the plant after the March 11 earthquake left water inside the plant's facilities, and the 10,000 tons of water found in the facility for nuclear waste disposal is believed to be part of the seawater, Hidehiko Nishiyama, a spokesman for the nuclear agency said.
By removing the water containing low-level radioactive substances in the waste disposal facility, TEPCO plans to instead fill the facility with a massive amount of highly radioactive water currently in the No. 2 reactor's turbine building and underground tunnel-like trench that is connected to the building, Nishiyama said.
Removal of contaminated water at the turbine buildings of several reactors is necessary to reduce the risk of workers being exposed to radioactive substances, which is hindering efforts to restore vital cooling functions to cool down the reactors and spent nuclear fuel pools.
Nishiyama also said that it had become necessary to release 1,500 tons of groundwater, also containing radioactive materials, found near the Nos. 5 and 6 reactor turbine buildings out of concern that the water could drown safety-related equipment. Of the six reactors at the Fukushima Daiichi plant, the Nos. 5 and 6 reactors have achieved ''cold shutdown,'' but Nishiyama said that he is afraid their cooling functions could be lost if the water level increases inside the buildings.
As for the impact of the disposal of the 11,500 tons of water, TEPCO said an adult's annual dose would be around 0.6 millisieverts if the person ate seaweed and fish caught nearby every day for a year, which is still about a quarter of the annual dose a person is usually exposed to from natural sources.
TEPCO is also stepping up efforts to stop highly radioactive water from leaking into the sea, and the company poured 13 kilograms of white bath agent into the trench connected to the No. 2 reactor turbine building to trace the source of highly radioactive water leaking into the sea.
But colored water did not come out from a seaside pit where a 20-centimeter crack has been found to be leaking radioactive water into the Pacific Ocean, Nishiyama said.
Highly radioactive water has been filling up the basement of the No. 2 reactor turbine building and the trench connected to it. Meanwhile, the water in the pit is believed to have come from the No. 2 reactor core, where fuel rods have partially melted.
TEPCO has revealed that radioactive iodine-131 more than 10,000 times the legal concentration limit was detected in the water found in the pit.
''We must prevent radioactive water from spreading in the sea as soon as possible,'' Chief Cabinet Secretary Edano said earlier in the day, adding that the longer the contamination continued, the larger the impact on the sea would be, even if radioactive materials were diluted in the sea.
In an effort to prevent further spread of seawater contamination, TEPCO is considering installing ''silt fence'' barriers in the sea where radioactive water is suspected to be flowing in, Nishiyama said, although he added that it would likely take several days to complete the work.
The barriers basically consist of curtains attached with weights, which TEPCO hopes will contain the contaminated water. One of the barriers would be placed in front of the No. 2 reactor's water intake, close to the pit in question, among other places.
(Distributed by Kyodo News on April 5, 2011)
With the total amount of water to reach 11,500 tons, including contaminated groundwater from near the No. 5 and No. 6 reactors, the government said the disposal was unavoidable in order to secure safety. The level of radioactive substances in the water is up to 500 times the legal limit permitted for release in the environment.
The government's nuclear agency said the disposal will pose ''no major health risk'' and experts say that the radioactive materials are likely to be diluted in the sea, but it remains uncertain how the marine environment will be affected when taking into account the impact of highly radioactive water already leaking into the sea from the plant located on the coast of Fukushima Prefecture.
The utility known as TEPCO used colored powder Monday morning to determine how the highly radioactive water, believed to originate from the No. 2 reactor, made its way into the sea. But the Nuclear and Industrial Safety Agency said that it was not able to confirm the route of flow.
In announcing the decision to dispose of the low-level radioactive water, top government spokesman Yukio Edano said, ''We've placed priority on not letting the highly radioactive water flow into the sea.''
Massive tsunami waves that hit the plant after the March 11 earthquake left water inside the plant's facilities, and the 10,000 tons of water found in the facility for nuclear waste disposal is believed to be part of the seawater, Hidehiko Nishiyama, a spokesman for the nuclear agency said.
By removing the water containing low-level radioactive substances in the waste disposal facility, TEPCO plans to instead fill the facility with a massive amount of highly radioactive water currently in the No. 2 reactor's turbine building and underground tunnel-like trench that is connected to the building, Nishiyama said.
Removal of contaminated water at the turbine buildings of several reactors is necessary to reduce the risk of workers being exposed to radioactive substances, which is hindering efforts to restore vital cooling functions to cool down the reactors and spent nuclear fuel pools.
Nishiyama also said that it had become necessary to release 1,500 tons of groundwater, also containing radioactive materials, found near the Nos. 5 and 6 reactor turbine buildings out of concern that the water could drown safety-related equipment. Of the six reactors at the Fukushima Daiichi plant, the Nos. 5 and 6 reactors have achieved ''cold shutdown,'' but Nishiyama said that he is afraid their cooling functions could be lost if the water level increases inside the buildings.
As for the impact of the disposal of the 11,500 tons of water, TEPCO said an adult's annual dose would be around 0.6 millisieverts if the person ate seaweed and fish caught nearby every day for a year, which is still about a quarter of the annual dose a person is usually exposed to from natural sources.
TEPCO is also stepping up efforts to stop highly radioactive water from leaking into the sea, and the company poured 13 kilograms of white bath agent into the trench connected to the No. 2 reactor turbine building to trace the source of highly radioactive water leaking into the sea.
But colored water did not come out from a seaside pit where a 20-centimeter crack has been found to be leaking radioactive water into the Pacific Ocean, Nishiyama said.
Highly radioactive water has been filling up the basement of the No. 2 reactor turbine building and the trench connected to it. Meanwhile, the water in the pit is believed to have come from the No. 2 reactor core, where fuel rods have partially melted.
TEPCO has revealed that radioactive iodine-131 more than 10,000 times the legal concentration limit was detected in the water found in the pit.
''We must prevent radioactive water from spreading in the sea as soon as possible,'' Chief Cabinet Secretary Edano said earlier in the day, adding that the longer the contamination continued, the larger the impact on the sea would be, even if radioactive materials were diluted in the sea.
In an effort to prevent further spread of seawater contamination, TEPCO is considering installing ''silt fence'' barriers in the sea where radioactive water is suspected to be flowing in, Nishiyama said, although he added that it would likely take several days to complete the work.
The barriers basically consist of curtains attached with weights, which TEPCO hopes will contain the contaminated water. One of the barriers would be placed in front of the No. 2 reactor's water intake, close to the pit in question, among other places.
(Distributed by Kyodo News on April 5, 2011)
