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January 31, 2014, 5:47 PM
Fukushima Watch: New Technology to Stop Deadly StrontiumLocal government officials and nuclear experts inspect
a construction site to prevent the seepage of contamination water
into the sea, at Fukushima Daiichi nuclear plant on Aug. 6, 2013
A new method to stop highly toxic radioactive strontium in ground
water from flowing into the sea using American technology will start in
February at the Fukushima Daiichi nuclear power plant.
Among the radioactive materials that were dispersed at the site, the potentially lethal alkaline earth metal poses the biggest immediate
concern, because, unlike cesium, it doesn’t get trapped in soil and
tends to accumulate in bones of fish and animals if ingested.
More In Fukushima Watch
Also, almost all other
radioactive materials except
for the relatively less harmful
tritium can be removed by
ALPS, the plant’s water
cleaning system. Since this
system only came online in
recent months and is not yet
fully operational, the water
collected from the melted
reactors in the early days of
the plant’s decommissioning
efforts still contains radioactive cesium and strontium.
Leakage from storage tanks last year left the surrounding soil
contaminated with those two radioactive materials, and strontium
has been slowly moving to deeper into ground water, which could be
moving toward the ocean.
The technology to be introduced uses apatite: a mineral that’s similar
to bone in its makeup and has the ability to capture and hold certain
elements including strontium.
At the Hanford site in southwestern Washington state, where the U.S. government produced more than 20 million pieces of uranium metal
fuel for nine nuclear reactors, apatite is used to block strontium from
liquid nuclear waste in soil from flowing into the adjacent Columbia
river, according to the U.S. government’s website.
“We’ll have to see if the technology works in a salt water environment,” said Tatsuya Shinkawa, director of the Japanese
government’s Nuclear Accident Response Office. “It has captured 90%
of the strontium in the ground water at the Hanford site. But that
site is far from the sea, and this method hasn’t been used in an
environment so close to the ocean.”
The government plans to conduct tests from February to May by putting a cylindrical case filled with pebbles covered with apatite into
the ground water, and if necessary improve the technology to work
with salt water. The case will be about 20 meters long and 1.5 meters
in diameter. “If it goes well, we will probably make an apatite wall
between the tanks and the sea,” Mr. Shinkawa said.
The use of apatite is one of 780 suggestions from around the world that Japan’s International Research Institute for Nuclear
Decommissioning received last year in response to its call for
solutions of the contaminated water problem.
Radiation levels in groundwater sampled from several monitoring wells have been very slowly rising since last summer and radioactive
strontium has been detected since October, according to data from
Tokyo Electric Power Co., which operates the Fukushima Daiichi plant.
Leaks started in early 2013, and Tepco considers the time gap came
because radioactive materials tend to move slowly in underground.
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Fukushima Watch: In for the Long HaulJapan National Press Club
Tokyo Electric Power Company employees work at the emergency command center
at the Fukushima Daiichi Nuclear Power Plant in Fukushima Prefecture, Japan, on Jan. 15, 2014
Thousands of well-wishing messages are plastered across the walls of
the decommissioning nerve center at Fukushima Daiichi. Sent in from around Japan and overseas, they praise the courage of workers at the
crippled nuclear plant and pray for their good health. Facing the
daunting task of cleaning up after one of the worst nuclear disasters
in history, workers at the site clearly need all the encouragement they
can get.
The quake-resistant emergency response center has become the
defacto command post for those on the frontline of the cleanup
operation. Built just eight months before the March 2011 disaster,
it was one of the only buildings to escape damage as a massive
earthquake and tsunami struck the plant, triggering a triple nuclear
meltdown.
At the center around 200 workers in blue uniforms oversee ongoing
operations in the plant and direct the highly sensitive and
potentially dangerous job of removing fuel rods from one of the
plant’s damaged reactor units, with around 80 of them taking turns to
work through the night to respond to any emergencies.
Akira Ono, chief of the Fukushima Daiichi
Nuclear Power Plant, answers questions from
reporters at the plant’s emergency command
center on Jan. 15.
“Decommissioning basically begins by removing fuel rods. In that
sense, I think we’ve finally taken our first step in the decommissioning
of Fukushima Daiichi,” plant chief Akira Ono told a group of reporters
taking part in a media tour of the plant Wednesday. Mr. Ono, who is
responsible for an average of 3,000 workers on the site on any given
day, said the multibillion dollar cleanup is expected to take 30 to 40
years.
The fuel removal process alone is set to take a year. The potentially
hazardous task requires 1,533 assemblies holding fresh and spent fuel
to be taken from a storage pool on top of reactor No. 4 and moved to
a more secure common pool serving all six of the plant’s reactors.
While the successful removal of fuel from unit 4 will relieve one big
source of anxiety, there are much more difficult tasks lying ahead,
including the cleaning up of the three reactors that suffered
meltdowns.
As the bus carrying reporters drove past by unit 3 toward units 1 and
2, readings on a dosimeter carried by an employee of plant operator
Tokyo Electric Power Co.9501.TO -1.60% spiked at over 600
microsieverts per hour, compared with a reading of around 10
microsieverts just seconds earlier. Reactors 1-3 are so highly
contaminated that no one, even in a protective suit, can enter the
buildings. That means almost all the cleanup work at the three units
will have to be undertaken by remote-controlled robots.
The plant faces other pressing issues, too, including the risks posed byheavily contaminated water. About 400 metric tons of contaminated
water are generated every day as large amounts of groundwater flow
into the site and wash through the damaged reactor buildings. With
over 400,000 tons of water stored at the site in about 1,000 tanks,
there has been concern that another major earthquake could lead to
a large radioactive discharge into the environment. Disclosures last
year revealed that the storage tanks have sprung leaks, and that
some radioactive materials are seeping into the nearby ocean.
“There are still many things we need to do,” Mr. Ono said. “In the
immediate aftermath of the disaster we prioritized speed over
quality…now we need to change both our approach and our
equipment to facilitate our work over the next 30 to 40 years,” he
said.
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