Japan may look to extend the evacuation zone around the quake-damaged Fukushima Daiichi nuclear power plant, the government's top spokesman said Thursday, as towns and villages around the plant continued to feel the impact of a radiation fallout, even after the plant itself showed signs of moving toward stability.
Japan
may
look to extend the evacuation zone around the quake-damaged Fukushima Daiichi
nuclear power plant, the government's top spokesman said Thursday, as towns and
villages around the plant continued to feel the impact of a radiation fallout,
even after the plant itself showed signs of moving toward stability.
Chief Cabinet Secretary Yukio Edano said the current 20-kilometer evacuation
zone may need to be enlarged since the original parameters were established in
relation to short-term exposure. The plant emergency caused by an earthquake
and tsunami on March 11 is now nearing the end of its fourth week. There is a
further 10-km band in which residents are urged to stay indoors as much as
possible.
"Current evacuation orders apply to areas where people are in danger of
having received 50 millisieverts. We are now looking into what to do with other
areas where, with prolonged exposure, people may receive that amount,"
Edano said. A 50 millisievert amount represents the annual exposure limit for a
nuclear plant worker.
The mayor of one town just outside the 30-km radius reacted angrily to the
proposed action, saying the government should have thought ahead earlier in the
crisis.
The town, Kawamata, located northwest of the plant, has seen elevated radiation
levels and is one of seven municipalities from which sales of local produce has
been banned.
"We are hearing that it may take months for the plant to settle down, and
only now are they talking about expanding the zone?" said Michio Furukawa,
the mayor of Kawamata.
"What we want to know is when this will all end?" he said.
Senior nuclear regulator Hidehiko Nishiyama offered apologies for the possible
further dislocation to those living in the area. He identified a series of
hydrogen explosions at the plant days after the earthquake as the primary cause
of the widespread radiation.
"The explosions sent radioactive materials flying to areas far outside the
nuclear complex," Nishiyama said in a press conference. "Radioactive
materials, once spread, cannot be put back. The best we can do is to stabilize
the damaged reactors and prevent further emissions of radiation."
In an effort to head off further hydrogen explosions, the plant operator, Tokyo
Electric Power Co., Wednesday began streaming nitrogen gas into Reactor No. 1,
one of the less damaged of the three crippled units.
Reactor No. 1's pressure and containment vessels are seen to have come out
relatively unscathed by the overheating of the reactor core following the
failure of the cooling system on March 11. But as the fuel cooled down and more
steam condensed into water, fears grew that the pressure inside the containment
vessel would fall sharply, allowing air to come in and create a dangerous mix
of hydrogen and oxygen inside the vessel. Nitrogen injection is designed to
forestall the entry of oxygen.
"The injection of gas is proceeding smoothly," a Tepco company
official said at a press briefing. The process began around 1 a.m. local time
Thursday and will continue for about six days, he said, adding that the measure
was having the desired effect of slightly raising the pressure within the
container vessel.
Tepco also announced that its president, Masataka Shimizu, had returned to work
after being hospitalized for more than a week as his company was blamed for
power outages and radioactive contamination that swept eastern
Japan
.
Shimizu
will assume the role leading
a joint task force with the government to support evacuees, allowing Chairman
Tsunehisa Katsumata to continue his role of overseeing the company's effort to
bring the plant under control, according to Tepco spokesman Naoyuki Matsumoto.
The other two heavily damaged units--Reactors Nos. 2 and 3--stayed in a
relatively stable condition Thursday, due to the continued pumping in of cold
water to cool the reactor cores.
But Tadashi Narabayashi, a professor at
Hokkaido
University
and
an expert in reactor engineering, said the situation is not sustainable,
because the massive water injection results in overflowing of irradiated water
from these reactors and the contamination of the facilities. This forces
operators to reduce the amount of water pumped in, causing the reactors to heat
up again. "Unless a cooling system is restored, in which water is
recirculated within the system, the reactors cannot be stabilized on a sustained
basis," he said.
Meanwhile, Edano denied a claim by a
U.S.
lawmaker that part of the No. 2 reactor core at the plant had melted through
its pressure vessel.
"I am not sure what the reasoning behind the lawmaker's statement
was," he said. "The unfortunate situation (at reactor No. 2), which
continues unchanged, is that the fuel rods are partially exposed, and we are
doing all that we can to reduce the risks created by this situation and to
address the problem."
On Wednesday, Rep. Ed Markey, a Massachusetts Democrat and a critic of nuclear
power, said the U.S. Nuclear Regulatory Commission had informed him "the
core of Unit Two has gotten so hot that part of it has probably melted through
the reactor pressure vessel."
Later Wednesday, an NRC official disputed Markey's remarks, saying that while
there was significant fuel damage in all three reactors, "We don't believe
at this point in time that the core has left the vessel."
The recovery efforts have received some supportive words from the British
government, which said that it was easing its travel restrictions to
Tokyo
based
on its scientific analysis of the current situation.
"Although the situation at
Fukushima
will
remain of concern for some time, the risks are gradually declining as the reactors
cool and as facilities to stabilise them are established." the
government's Foreign and Commonwealth Office said on its website.
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