Perilous
Times
Crippled Japan nuke reactors have fatally high radiation, no
water
By MARI YAMAGUCHI, Associated Press
TOKYO — Japan's crippled nuclear reactors still have fatally high
radiation levels and hardly any water to cool them,, according to
an internal examination Tuesday that renews doubts about the
plant's stability.
A tool equipped with a tiny video camera, a thermometer, a
dosimeter and a water gauge was used to assess damage inside the
reactor's containment chambers for the second time since the
tsunami swept into the Fukushima Dai-ichi plant a year ago. The
probe done in January failed to find the water surface and
provided only images showing steam, unidentified parts and rusty
metal surfaces scarred by exposure to radiation, heat and
humidity.
The data collected from the probes showed the damage from the
disaster was so severe, the plant operator will have to develop
special equipment and technology to tolerate the harsh environment
and decommission the plant, a process expected to last decades.
Tuesday's examination with an industrial endoscope detected
radiation levels up to 100 times the fatal dose inside the
chambers. Plant officials previously said more than half of melted
fuel has breached the cores and dropped to the floor of the
primary containment vessel, some of it splashing against the wall
or the floor.
Particles from melted fuel have probably sent radiation levels up
to dangerously high 70 sieverts per hour inside the containers,
said Junichi Matsumoto, spokesman for Tokyo Electric Power Co.
"It's extremely high," he said, adding that an endoscope would
last only 14 hours in that condition. "We have to develop
equipment that can tolerate high radiation" when locating and
removing melted fuel during the decommissioning.
The probe also found the containment vessels — a beaker-shaped
container enclosing the core — had cooling water up to only 60
centimeters (2 feet) from the bottom, far below the 10 meters
(yards) estimated when the government declared the plant stable in
December.
Finding the water level was important to help locate damaged areas
where radioactive water is escaping.
He said that the actual water level inside the chambers were way
off the estimate, which had used data that turned out to be
unreliable. But the results don't affect the plant's "cold
shutdown status" because the water temperature was about 50
degrees Celsius (122 Fahrenheit), indicating the melted fuel is
cooled.
Three Dai-ichi reactors had meltdowns, but the No. 2 reactor is
the only one that has been examined because radiation levels
inside the reactor building are relatively low and its container
is designed with a convenient slot to send in the endoscope.
The exact conditions of the other two reactors, where hydrogen
explosions damaged their buildings, are still unknown. Simulations
have indicated that more fuel inside No. 1 has breached the core
than the other two, but radiation at No. 3 remains the highest.
The high radiation levels inside the No. 2 reactor's chamber mean
it's inaccessible to the workers, but parts of the reactor
building are accessible for a few minutes at a time — with the
workers wearing full protection.
Last year's massive earthquake and a tsunami set off the worst
nuclear accident since Chernobyl, sending three reactor cores to
melt and causing massive radiation leaks. The government said in
December that the reactors are safely cooled and the plant has
stabilized, while experts have questioned its vulnerability.
During a recent visit by a group of journalists including The
Associated Press, the head of the plant said it remains vulnerable
to strong aftershocks and tsunami and containing contaminated
water and radiation is a challenge. Radioactive water had leaked
into the ocean several times already.
Workers found the fresh leak of 120 tons from a water treatment
unit this week from one of its hoses, with estimated 80 liters (20
gallons) escaping into the ocean, Matsumoto said. Officials are
still investigating its impact.
Fukukushima's accident has instilled public distrust and concerns
about nuclear safety, making it difficult for the government to
start up reactors even after regular safety checks. All but one of
Japan's 54 reactors are now offline, with the last one scheduled
to stop in early May.