Nuclear engineers in Japan are readying to move uranium and plutonium
fuel rods at the Fukushima Daiichi nuclear power plant in their most
difficult and dangerous task since the plant’s runaway reactors were
brought under control two years ago.
Tokyo Electric Power Co (TEPCO) will this month begin taking out fuel
rods from a pool inside a reactor building at the tsunami-hit plant, in
a technically challenging operation that will test the utility’s
abilities after months of setbacks and glitches.
Experts say the operation is a tricky but essential step in the
decades-long decommissioning process after the worst atomic accident in a
generation.
More than 1,500 nuclear fuel assemblies, the bulk of them used, but
including 200 new ones, need to be pulled out of the pool where they
were being stored when the tsunami smashed into Fukushima in March 2011.
Reactor No. 4 was not in operation at the time but hydrogen from
Reactor No. 3 escaped into the building and exploded, tearing the roof
off and leaving it at the mercy of natural hazards like earthquakes,
storms or another tsunami.
TEPCO says it has not yet found any damage to the assemblies at No.
4, which contain an mixture of uranium and plutonium, but will be
monitoring for abnormalities.
The removal of fuel is part of regular work at any nuclear power
plant, but “conditions are different from normal because of the
disaster,” said company spokeswoman Mayumi Yoshida.
“It is crucial. It is a first big step toward decommissioning the
reactors,” she said. “Being fully aware of risks, we are determined to
go ahead with operations cautiously and securely.”
Chunks of debris that were sent flying into the pool as reactor
buildings exploded have largely been removed and a crane has been
installed. A protective hood has been erected over the building’s
skeleton in a bid to prevent radioactive leaks.
A remotely-controlled grabber will sink into the pool and hook onto a
fuel assembly, which it will pull up and place inside a fully immersed
cask.
The 4.5-meter bundles weighing 300 kilograms have to be kept in water
throughout the operation to keep them cool, the spokeswoman said.
The 91-ton cask will then be hauled from the pool—containing as many
as 22 fuel assemblies and a lot of water—to be loaded onto a trailer and
taken to a different storage pool where the operation will be reversed.
Experts warn that any slip-ups could quickly snowball and even minor
mishaps will create considerable delays to the already long and
complicated decommissioning.
“This is the first practical milestone for the project,” said Hiroshi
Miyano, a nuclear systems expert and visiting professor at Hosei
University in Tokyo. “Any trouble in this operation will considerably
affect the timetable for the entire project. This is an operation TEPCO
cannot afford to bungle.”
Miyano’s comments reflect an increasingly widespread view that the
giant utility is not capable of dealing with the mess its nuclear plant
has created.
Months of setbacks have included multiple leaks from tanks storing
the water used to keep reactors cool, and a power outage caused when a
rat electrocuted itself on a circuit board.
TEPCO’s management of the problems has been criticized as haphazard
and uncoordinated, with one government minister saying it was like
watching someone playing “whack-a-mole.”
The full decommissioning of Fukushima is likely to take decades and
include tasks that have never been attempted anywhere in the world, such
as the removal of reactor cores that have probably melted beyond
recognition.
Meanwhile, villages and towns nearby remain largely empty, their
residents unable or unwilling to return to live in the shadow of the
leaking plant because of the fear of radiation.
No comments:
Post a Comment