A U.S. military barge carrying pure water, bottom, leaves the quay of Tokyo Electric Power's Fukushima Dai-Ichi nuclear power plant in Fukushima prefecture, Japan, on April 4, 2011. Source: Japan Ministry of Defense via Bloomberg
April 7 (Bloomberg) -- Richard Lester, head of the department of nuclear science and engineering at the Massachusetts Institute of Technology, talks about the outlook for nuclear power following the crisis at Tokyo Electric Power Co.'s tsunami-damaged facility in northeastern Japan.
Lester speaks with Carol Massar and Matt Miller on Bloomberg Television's "Street Smart." (Source: Bloomberg)
A 7.1-magnitude earthquake minutes
before midnight spared the stricken Fukushima Dai-Ichi nuclear
plant in Japan, although workers struggling to cool radioactive
fuel were evacuated, Tokyo Electric Power Co. said based on its
initial assessment.
The aftershock was the strongest since March 11 when a
record 9-magnitude earthquake and tsunami devastated the coast
of Northeast Japan. No unusual conditions were observed at the
plant afterward, the utility, known as Tepco, and Japan’s
Nuclear and Industrial Safety Agency said in statements.
No unusual measurements of water level, pressure or other
operations were found at the No. 3 and No. 4 reactors at the
six-unit plant, Tepco officials told reporters today.
“Indications of new leakage or a change in radiation
levels will be the only way they’ll tell if there’s further
damage,” Murray Jennix, a nuclear engineer who specialized in
radioactive containment leaks and teaches at San Diego State
University, said in a telephone interview. “You’ve got cracks
that could have been made bigger.”
Tepco said April 6 engineers had plugged a leak of
radioactive water into the ocean from a pit near the No. 2
reactor after several failed attempts. Concentration of
radioactive iodine in seawater near the reactor discharge pipe
fell by half, to 140,000 times the regulatory limit, the company
said yesterday.
‘The Main Fear’
“The main fear is more structural damage, leading to
additional cracks or reopening of the fixed crack,” Peter
Hosemann, an assistant professor of nuclear engineering at the
University of California at Berkeley, said in an e-mailed
message. “Radioactivity can leak again if cracks open.”
A day may be needed to detect additional damage at the
plant, he said.
Crews at the crippled nuclear station north of Tokyo will
continue pumping nitrogen into the No. 1 reactor to prevent
hydrogen explosions of the type that damaged radiation
containment buildings last month. Injection of nitrogen, the
inert gas that comprises most of air, may take six days
spokesman Yoshinori Mori said before today’s quake.
“They are manually injecting nitrogen through a very
narrow pipe,” Tadashi Narabayashi, a professor of nuclear
engineering at Hokkaido University in northern Japan, said by
phone yesterday. “High radiation levels in the building are
also making it difficult as workers have to keep rotating.”
Cooling the Reactors
The March 11 tsunami flooded emergency generators at the
Fukushima plant, triggering cooling-system failures at four of
the plant’s six nuclear units.
Tepco is still using emergency pumps to cool the reactors
and pools holding spent fuel, almost four weeks after the
initial disaster. Three blasts damaged reactor buildings and
hurled radiation into the air last month.
About 3.64 million households in six Japanese prefectures
were without power following the aftershock, Kyodo News
reported, citing Tohoku Electric Power Co., which operates in
seven prefectures.
The Rokkasho nuclear-fuel reprocessing plant and the
Higashidori nuclear power plant lost power and were operating on
backup diesel generators, the nuclear safety agency said today
in a statement. Two of three power lines to the Onagawa nuclear
power plant also were disabled, it said.
Five other power stations were shut down by the aftershock,
broadcaster NHK reported, citing Tohoku Electric.
‘Tremendously Smaller’
“What occurred today is an aftershock in the same area and
rupture zone to the magnitude-9 main shock that occurred about a
month ago,” said Don Blakeman, a geophysicist in the U.S.
National Earthquake Information Center in Golden, Colorado. “It
is tremendously smaller than the main shock. The main shock
caused about 80 times more ground movement.”
The 7.1 aftershock was the fourth of magnitude-7 or higher
since the major quake on March 11, according to the Japanese
Meteorological Agency. The largest measured 7.7, about 30
minutes after the record quake, according to the agency’s
website.
Police and fire officials reported the number of people
injured in today’s earthquake reached 82 as of 3:30 a.m. local
time, public broadcaster NHK said on its website.
There have been 464 aftershocks of magnitude 5 or greater,
counting today’s, according to agency statistics.
More than 27,300 people are dead or missing after the
initial natural disaster in northeastern Japan, according to the
latest figures from the National Police Agency.
To contact the reporters on this story:
Akiko Nishimae in New York at
anishimae3@bloomberg.net;
Jim Polson in New York at
jpolson@bloomberg.net;
Ichiro Suzuki in Tokyo at
isuzuki@bloomberg.net
To contact the editors responsible for this story:
Teo Chian Wei at
cwteo@bloomberg.net;
Susan Warren at
susanwarren@bloomberg.net