Source: http://www.nytimes.com/2011/04/15/world/asia/15cleanup.html?_r=1&ref=asia
Hiroko Tabuchi, New York Times, April 14, 2011
TOKYO Even before the troubled Fukushima Daiichi nuclear
plant has been brought under control, two conglomerates vying
for contracts in an eventual cleanup are estimating that the effort
could take 10 years — or 30.
Nuclear Company to Compensate Evacuees in Japan (April 16, 2011)
The widely divergent outlooks underscore the basic uncertainties
clouding any forecast for Fukushima. It is far from clear when the
cooling system will be restored and radiation emission halted; how
soon workers can access some parts of the plant; and how bad the
damage to the reactors, their fuel and nearby stored fuel turns out
to be. The United States Nuclear Regulatory Commission has
warned that at least one reactor’s fuel may even have leaked out
of the reactor pressure vessel.
A global team led by Hitachi said Thursday that it would take at least
three decades to return the site to what engineers refer to as a “green
field” state, meaning within legal limits of radiation for any residents.
Toshiba, Japan’s biggest supplier of nuclear reactors, said it could
take as little as 10 years.
Both companies have large nuclear-related businesses and appear
to be eager to speak about endgame possibilities for a crisis that has
heightened global public mistrust of nuclear power. Billions of dollars
are likely to be at stake in the cleanup, which could help Hitachi and
Toshiba improve their bottom lines. The two said last week that annual
profits would fall short of their forecasts because of the widespread
disruptions in production and supply chains caused by the disaster.
At a roundtable with reporters on Thursday, Toshiba’s chief executive,
Norio Sasaki, wielded an inch-thick proposal outlining the dismantlement
plan submitted to the plant’s operator, Tokyo Electric Power Company,
this month. Hitachi has presented a competing plan.
The scale and complexity of the challenge are unprecedented. No
nuclear reactor has ever been fully decommissioned in Japan, let
alone the four certain to be dismantled at Fukushima Daiichi after
being flooded with seawater to avert meltdowns and after suffering
explosions and other damage. The final fates of the two other reactors
there have not been announced, but they, too, may need to be
decommissioned.
The 1979 accident at Three Mile Island in Pennsylvania involved just
one reactor, and though there was a partial meltdown of the nuclear
fuel rods, the chamber holding them did not rupture. The cleanup there
still took 14 years and cost about $1 billion. (Two reactors that continue
to operate at the site are set to be decommissioned in 2014.)
Recovery from the 1986 disaster at Chernobyl in Ukraine, meanwhile,
is an example engineers are not eager to follow. Following explosions
and a fire that sent huge radioactive plumes into the atmosphere,
workers covered the remains of the reactor with sand and lead and
eventually entombed it with concrete to halt the release of radiation.
The concrete coffin still remains at Chernobyl, and the area is
uninhabitable.
For now, workers in Japan are still trying to stem leaks of highly
radioactive water from the plant even as they add to the flow by
continuing to pump in water — now fresh, not saltwater. They are also
racing to revive the contained cooling systems that circulate water and
do not bleed contaminants.
But serious challenges remain, including what Japan’s nuclear regulator
said Thursday were rising temperatures at one of the units, as well as
a series of strong aftershocks. Later, Hidehiko Nishiyama, the deputy
director general of Japan’s Nuclear and Industrial Safety Agency, said
the situation at the plant remained “difficult.”
Still, Toshiba’s engineers expect the plant to stabilize “in several
months,” Mr. Sasaki said, and for full-scale cooling to resume. It
would be five years before engineers would be able to open the
pressure vessels to remove the nuclear fuel, he said, and dismantling
the reactors and cleaning up radiation at the plant would take at least
another five years.
Toshiba’s team includes engineers from Westinghouse, whose majority
owner is Toshiba, and the Babcock & Wilcox Company, an energy
technology and services company that handles the disposal of
hazardous materials. The two companies helped shut down the
damaged reactor at Three Mile Island.
A Hitachi spokesman in Tokyo, Yuichi Izumisawa, said that the 10-year
projection was overly optimistic. He said that Hitachi’s engineers
expected it to take that long just to remove the nuclear fuel rods from
the plant and place them in casks to transport to a safe storage facility.
Only then can the dismantling of the plant’s structures begin, he said,
followed by the cleanup of the remaining radiation.
Hitachi, the country’s second biggest supplier of reactors, has a team
of 50 experts working on its dismantling plan. It has a joint nuclear
venture with General Electric and is also working with the American
nuclear operator Exelon and Bechtel, an engineering company.
“You basically need to dismantle the plant from the inside, and the
inside is still very radioactive,” Mr. Izumisawa said. “At Hitachi, we are
baffled over what kind of technology would allow everything to be
finished in 10 years.”
Tetsuo Matsumoto, a professor of nuclear engineering at Tokyo City
University, said that how long the decommissioning process would take
depended heavily on the state of the nuclear fuel.
“Will it still be shaped like rods? Or will it have melted and collapsed
into a big mass?” he said. “It could be 10 years or it could be 30. You
just won’t know until you open up the reactor.”
Ken Ijichi contributed reporting.
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