Advertise on NYTimes.com News Analysis Japan May Declare Control of Reactors, Over Serious DoubtsTepco Via Jiji Press/Agence France-Presse —Getty Images Workers sprayed water in March to cool the spent nuclear fuel in a reactor building at the Fukushima Daiichi nuclear plant. ByMARTIN FACKLER Published: December 14, 2011 Recommend Twitter Linkedin Sign In to E-Mail Print
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
a “cold shutdown,” a technical term normally used to describe intact reactors with fuel cores that
are in a safe and stable condition. Experts say that if it does announce a shutdown, as many
expect, it will simply reflect the government’s effort to fulfill a pledge to restore the plant’s
cooling system by year’s end and, according to some experts, not the true situation.
If the task force declares a cold shutdown, the next step will be moving the spent fuel rods innearby cooling pools to more secure storage, and eventually opening the reactors themselves.
However, many experts fear that the government is declaring victory only to appease growing
public anger over the accident, and that it may deflect attention from remaining threats to the
reactors’ safety. One of those — a large aftershock to the magnitude 9 earthquake on March 11,
which could knock out the jury-rigged new cooling system that the plant’s operator hastily built
after the accident — is considered a strong possibility by many seismologists.
They also said the term cold shutdown might give an exaggerated impression of stability to
severely damaged reactors with fuel cores that have not only melted down, but melted throughthe inner containment vessels and bored into the floor of their concrete outer containment
structures.
“The government wants to reassure the people that everything is under control, and do this by the
end of this year,” said Kazuhiko Kudo, a professor of nuclear engineering at Kyushu University.
“But what I want to know is, are they really ready to say this?”
Perhaps to give itself some wiggle room, the government is expected to use vague terminology,
announcing that the three damaged reactors are in a “state of cold shutdown.” Experts say that in
real terms, this will amount to a claim that the reactors’ temperatures can now be kept safely
below the boiling point of water, and that their melted cores are no longer at risk of resuming the
atomic chain reaction that could allow them to again heat up uncontrollably.
And indeed, experts credit the operator, the Tokyo Electric Power Company, or Tepco, with
making progress in regaining control of the damaged reactors. They say the plant’s makeshift
new cooling system, built with the help of American, French and Japanese companies, has
managed to cool the reactors’ cores, including the molten fuel attached to the outer containment
vessels.
Experts also say a new shedlike structure built over the heavily damaged Unit 1 reactor building
has helped cap the plant’s radiation leaks into the atmosphere. The building was one of threereactor buildings destroyed in hydrogen explosions in March that scattered dangerous particles
over a wide swath of northeastern Japan.
Still, experts say the term is usually reserved for healthy reactors, to indicate that they are safe
enough that their containment vessels can be opened up and their fuel rods taken out. But they
warn it may take far longer than even the government’s projected three years to begin cleaning