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Fukushima Daiichi’s Achilles
Heel: Unit 4′s Spent Fuel?
Fukushima Nuclear Crisis
EMF Computer Protection
Magnetic Field Detector
April 17, 2012
By Phred Dvorak
Just how dangerous is the situation at Japan’s crippled
Fukushima Daiichi nuclear plant? Very, according to U.S.
Senator Ron Wyden, a senior member of the Senate’s energy
committee who toured the plant earlier this month.
Another big earthquake or tsunami could send Fukushima
Daiichi’s fragile reactor buildings tumbling down, resulting
in “an even greater release of radiation than the initial
accident,” Mr. Wyden warned in a Monday letter to Japanese
Ambassador to the U.S. Ichiro Fujisaki.
In particular, Japan isn’t moving fast enough to remove
dangerous nuclear-fuel rods from the reactors, and the
U.S. should offer its help to speed things along, Mr. Wyden
urged, in letters to Ambassador Fujisaki, as well as U.S.
Energy Secretary Steven Chu, Secretary of State Hillary
Clinton and Nuclear Regulatory Commission Chairman Gregory
Jaczko.
Yoshikazu Nagai, a spokesman for Fukushima Daiichi operator
Tokyo Electric Power Co. said the company couldn’t comment
on the letter, and that all it can do is “proceed steadily
with the (cleanup) roadmap.” Japan’s Foreign Ministry
declined to comment.
Mr. Wyden’s warning touches on what some experts think is
the biggest problem at the Fukushima plant: another
earthquake or tsunami that exposes the least protected of
its nuclear fuel to outside air.
Fukushima Daiichi suffered meltdowns at three of its
reactors last year after the March 11 earthquake and tsunami
knocked out power in the area. Much of the nuclear fuel in
those three reactors is thought to be in a melted lump at
the bottom of the vessels that surround the core. That’s
bad, but at least the vessels shield the outside world from
the radioactive fuel.
But Fukushima Daiichi’s Unit 4 reactor was shut down for
maintenance when last year’s accident took place, meaning
the nuclear fuel rods were outside those protective vessels
and sitting in a pool of water, high up in the reactor
building, where they were being stored. The water in that
“spent fuel pool” keeps the rods cool and insulates them
from the outside. But if the pool should spring a leak, or
another earthquake bring the pool crashing down, all that
fuel would be exposed to the outside air, letting them heat
up and release massive amounts of radiation. Other reactors
have spent-fuel pools too, but they contain less fuel.
Tepco says an analysis it conducted on the Unit 4 pool
showed the building didn’t need reinforcing, but it went
ahead and reinforced the structure anyway, increasing its
safety margin by 20%. Tepco says it’s working to remove the
fuel rods as fast as it can. If all goes according to its
timetable, the utility could start taking the rods out in
2014.
Mr. Wyden points out, though, that the schedule allows up to
ten years to get all the spent fuel in all the Fukushima
reactor pools out — something he says is too risky.
“This schedule carries extraordinary and continuing risk if
further severe seismic events were to occur,” he wrote in
his letter to Ambassador Fujisaki. “The true earthquake risk
for the site was seriously underestimated and remains
unresolved.”
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