Nuclear Fuel Meltdown at Fukushima Daiichi Confirmed
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GLT
May 17, 2011, 6:09:55 AM5/17/11
to Philippine environment conservation
Nuclear Fuel Meltdown at Fukushima Daiichi Confirmed
TOKYO, Japan, May 13, 2011 (ENS) - Tokyo Electric Power Company,
operator of the damaged Fukushima Daiichi nuclear power plant,
revealed Thursday that nuclear fuel at one of the reactors is in a
state of "meltdown."
TEPCO officials said that most of the fuel rods in the Unit 1 reactor
have melted and fallen to the bottom of the reactor. They said cooling
water in this reactor has fallen to a level that would expose those
fuel rods that are still intact.
Holes have been created by melted nuclear fuel in piping at the bottom
of the reactor's pressure vessel, allowing tons of water the company
has been spraying into the reactor to cool the fuel to escape.
Workers check the water level indicator in the Unit 1 reactor building
at Fukushima Daiichi. May 10, 2011 (Photo courtesy TEPCO)
Still, TEPCO said that some water remains at the bottom of the reactor
vessel and is keeping the melted fuel cool.
TEPCO spokesman Junichi Matsumoto said the low level of water
indicates that the core of Unit 1 is more damaged than previously
believed.
But temperatures in Unit 1 are still below dangerous levels because
TEPCO continues to inject fresh water to cool the fuel, although much
of the injected water is leaking through holes at the bottom of the
vessel.
The new information on the state of the fuel in Unit 1 emerged after
workers repaired a water gauge Tuesday after entering the reactor
building for the first time since a March 12 hydrogen explosion at the
unit. Once fixed, the gauge showed that water in the reactor was at
least one meter (39 inches) below the fuel rods.
Under a strategy approved last month, TEPCO planned to fill the
reactor containment vessel with water and circulate the water through
a heat exchanger.
But today, an official of Japan's nuclear safety agency told reporters
that flooding the containment vessel may not be necessary and the
company should change its strategy.
Hidehiko Nishiyama said TEPCO only needs to inject water to a height
that would allow the system to work.
Aerial view of the Unit 1 reactor after a hydrogen gas explosion March
12. (Photo by Air Photo Service Co. Ltd., Japan)
Economy, Trade and Industry Minister Banri Kaieda said today that the
water injected into the Unit 1 reactor has in fact leaked out through
holes created by the meltdown. For this reason TEPCO's plan must be
reviewed, he said.
TEPCO has injected more than 10,000 tons of water into the Unit 1
reactor but less than half that amount is thought to remain in the
reactor or the containment vessel.
The utility says the leaked water is likely in the basement of the
reactor building, but high radiation levels prevent workers from
entering the area.
Robots could be used instead, but TEPCO says their wireless remote
control system may not extend to the basement.
TEPCO also has been spraying tons of fresh water onto Units 2 and 3,
and contaminated cooling water from these reactor cores has been
leaking. To prevent an estimated 70,000 tons of contaminated water
from entering the Pacific Ocean, workers have been pumping it into a
waste processing building while a system to purify the water is
installed.
Still, some highly-radioactive water has leaked into the sea past the
silt fence that TEPCO has set up to contain it.
Drawing of containment cover for the Fukushima Daiichi Unit 1 reactor.
(Image courtesy TEPCO)
Today, TEPCO announced it has begun preparation work to install a
cover that will completely encase the Unit 1 reactor building, in
accordance with its plan announced in April.
The cover will be installed "as an emergency measure to prevent the
diffusion of radioactive substances until mid-to-long term measures
including radiation shielding are implemented," the company said.
TEPCO said it will first level the ground to bring heavy crawler
cranes onto the site. The crawler cranes will "minimize the exposure
dose of the workers and shorten the work period," the company said.
Installation of the cover is scheduled to begin in June.
The power plant 220 km (140 miles) north of Tokyo on Japan's Pacific
coast lost cooling functions on March 11 when the magnitude 9.0
earthquake cut off the outside power supply. The resulting tsunami
disabled generators that were supposed to operate the reactors'
cooling systems in case of emergency.
In the five days following the quake, there were hydrogen gas
explosions in three of the plant's six reactors, including Unit 1, and
partial meltdown of nuclear fuel rods in Units 1, 2, and 3.
Radiation releases caused more than 80,000 people to evacuate a 20 km
(12 mile) radius around the power plant, and radiation has spread into
the sea, the soil around the power plant and through the air.
The accident is rated at Level 7, the highest on the UN's
International Nuclear Event Scale, and is considered the world's
second most serious nuclear disaster, after Chernobyl.
Read more:
http://www.ens-newswire.com/ens/may2011/2011-05-13-01.html
TOKYO, Japan, May 13, 2011 (ENS) - Tokyo Electric Power Company,
operator of the damaged Fukushima Daiichi nuclear power plant,
revealed Thursday that nuclear fuel at one of the reactors is in a
state of "meltdown."
TEPCO officials said that most of the fuel rods in the Unit 1 reactor
have melted and fallen to the bottom of the reactor. They said cooling
water in this reactor has fallen to a level that would expose those
fuel rods that are still intact.
Holes have been created by melted nuclear fuel in piping at the bottom
of the reactor's pressure vessel, allowing tons of water the company
has been spraying into the reactor to cool the fuel to escape.
Workers check the water level indicator in the Unit 1 reactor building
at Fukushima Daiichi. May 10, 2011 (Photo courtesy TEPCO)
Still, TEPCO said that some water remains at the bottom of the reactor
vessel and is keeping the melted fuel cool.
TEPCO spokesman Junichi Matsumoto said the low level of water
indicates that the core of Unit 1 is more damaged than previously
believed.
But temperatures in Unit 1 are still below dangerous levels because
TEPCO continues to inject fresh water to cool the fuel, although much
of the injected water is leaking through holes at the bottom of the
vessel.
The new information on the state of the fuel in Unit 1 emerged after
workers repaired a water gauge Tuesday after entering the reactor
building for the first time since a March 12 hydrogen explosion at the
unit. Once fixed, the gauge showed that water in the reactor was at
least one meter (39 inches) below the fuel rods.
Under a strategy approved last month, TEPCO planned to fill the
reactor containment vessel with water and circulate the water through
a heat exchanger.
But today, an official of Japan's nuclear safety agency told reporters
that flooding the containment vessel may not be necessary and the
company should change its strategy.
Hidehiko Nishiyama said TEPCO only needs to inject water to a height
that would allow the system to work.
Aerial view of the Unit 1 reactor after a hydrogen gas explosion March
12. (Photo by Air Photo Service Co. Ltd., Japan)
Economy, Trade and Industry Minister Banri Kaieda said today that the
water injected into the Unit 1 reactor has in fact leaked out through
holes created by the meltdown. For this reason TEPCO's plan must be
reviewed, he said.
TEPCO has injected more than 10,000 tons of water into the Unit 1
reactor but less than half that amount is thought to remain in the
reactor or the containment vessel.
The utility says the leaked water is likely in the basement of the
reactor building, but high radiation levels prevent workers from
entering the area.
Robots could be used instead, but TEPCO says their wireless remote
control system may not extend to the basement.
TEPCO also has been spraying tons of fresh water onto Units 2 and 3,
and contaminated cooling water from these reactor cores has been
leaking. To prevent an estimated 70,000 tons of contaminated water
from entering the Pacific Ocean, workers have been pumping it into a
waste processing building while a system to purify the water is
installed.
Still, some highly-radioactive water has leaked into the sea past the
silt fence that TEPCO has set up to contain it.
Drawing of containment cover for the Fukushima Daiichi Unit 1 reactor.
(Image courtesy TEPCO)
Today, TEPCO announced it has begun preparation work to install a
cover that will completely encase the Unit 1 reactor building, in
accordance with its plan announced in April.
The cover will be installed "as an emergency measure to prevent the
diffusion of radioactive substances until mid-to-long term measures
including radiation shielding are implemented," the company said.
TEPCO said it will first level the ground to bring heavy crawler
cranes onto the site. The crawler cranes will "minimize the exposure
dose of the workers and shorten the work period," the company said.
Installation of the cover is scheduled to begin in June.
The power plant 220 km (140 miles) north of Tokyo on Japan's Pacific
coast lost cooling functions on March 11 when the magnitude 9.0
earthquake cut off the outside power supply. The resulting tsunami
disabled generators that were supposed to operate the reactors'
cooling systems in case of emergency.
In the five days following the quake, there were hydrogen gas
explosions in three of the plant's six reactors, including Unit 1, and
partial meltdown of nuclear fuel rods in Units 1, 2, and 3.
Radiation releases caused more than 80,000 people to evacuate a 20 km
(12 mile) radius around the power plant, and radiation has spread into
the sea, the soil around the power plant and through the air.
The accident is rated at Level 7, the highest on the UN's
International Nuclear Event Scale, and is considered the world's
second most serious nuclear disaster, after Chernobyl.
Read more:
http://www.ens-newswire.com/ens/may2011/2011-05-13-01.html
jordytheother
Jun 24, 2011, 10:19:00 AM6/24/11
to Philippine environment conservation
Current Information Resources:
Good site for summary of Japanese news
http://ex-skf.blogspot.com/
Important links for Fukushima Daiichi
http://fukushimafaq.wikispaces.com/UsefulLinks
Good site for summary of Japanese news
http://ex-skf.blogspot.com/
Important links for Fukushima Daiichi
http://fukushimafaq.wikispaces.com/UsefulLinks
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