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Crucial Cooling Systems Restored at Fukushima Plant, Company Says
(about 3 hours later)
TOKYO — Two pools for storing spent nuclear fuel remained without vital cooling systems more than 24 hours after a partial power failure at the stricken Fukushima Daiichi nuclear plant in Japan on Tuesday, the operator said. The company said it had restored the flow of cooling water to two other pools also affected by the blackout.
TOKYO — Vital cooling systems at the stricken Fukushima Daiichi nuclear plant were restored by Wednesday morning, more than 24 hours after a partial power failure cut cooling water to four spent fuel pools, the company that operates the plant said. The latest problem raised new fears about the continuing vulnerability of the plant, which suffered a triple meltdown two years ago and still relies on makeshift equipment.
The operator, Tokyo Electric Power Company, said temperatures in the two uncooled pools still remain well within safe levels. It said its engineers were trying to repair a faulty switchboard that it blamed for the outage that began on Monday night, halting pumps that inject cooling water into the four pools located near the No. 1, No. 3 and No. 4 reactors.
Although the company said the latest issue was resolved long before it became a safety risk, the temporary breakdown appeared to expose a weakness in the plant’s cooling systems. The systems were hastily built by engineers during frantic attempts to regain control of overheating reactors soon after a devastating earthquake and tsunami started the crisis at the plant.
All three of those reactor buildings, which also house the pools, were damaged by hydrogen explosions caused by the triple meltdown at the plant two years ago, after a huge earthquake and tsunami destroyed reactor cooling systems. The company, known as Tepco, said the current loss of cooling water was manageable because temperatures would remain at safe levels for at least four days, and the plant also has backup systems.
The plant operator, Tokyo Electric Power Co. or Tepco, said a faulty switchboard appeared to be to blame in Monday’s power failure. While Tepco has backup generators on site, it appeared to have been unprepared for a switchboard failure.
Still, the problems underscore the continuing vulnerability of the plant, which is beginning a complex cleanup of the three damaged reactors that is expected to take decades. Some experts have warned that the current cooling systems, some of which were hastily built by engineers frantically struggling to regain control of the overheating reactors, could be knocked out by another large earthquake.
“Fukushima Daiichi still runs on makeshift equipment, and we are trying to switch to something more permanent and dependable,” a Tepco spokesman, Masayuki Ono, told reporters Tuesday as the company worked to restore the cooling systems.
"Fukushima Daiichi still runs on makeshift equipment, and we are trying to switch to something more permanent and dependable," a Tepco spokesman, Masayuki Ono, told reporters. "Considering the equipment situation, we may be pushing a little too hard."
The latest troubles also underscore the continuing worries about the safety of the plant, where a complex cleanup of three damaged reactors is expected to take decades. In particular, experts have warned the makeshift cooling systems could be knocked out by another large earthquake.
Much of the ongoing concern has focused on the pools near the reactors that are used to store spent fuel rods. These contain far more radioactive material and have less shielding from the outside than the reactors, raising the specter of another massive release of contaminated particles.
Much of the ongoing concern has focused on the fuel pools, which contain far more radioactive material than reactors and were built with less shielding, raising the specter of another massive release of radioactive materials.
The four pools affected by Monday’s blackout contained more than 8,000 highly contaminated fuel rods, Tepco said. That would be enough to release far more radioactive material than the original accident in March 2011, which forced the evacuation of some 160,000 residents in northeastern Japan. Many of those evacuees still live in temporary shelters and may never be able to return home.
The four pools affected by Monday’s blackout contain more than 8,800 highly radioactive fuel rods, Tepco said. That would be enough to release far more radioactive material than the original accident in March 2011, which forced the evacuation of some 160,000 residents in northeastern Japan. Many of those evacuees still live in temporary shelters and may never be able to return home.
On Tuesday, Tepco said it had restored cooling to two of the four pools by starting backup systems. It said it expected to soon resume cooling at a third pool, though restoring cooling water to the fourth pool might take until Wednesday.
With the company as the only source of information, it was impossible to independently assess the conditions at the plant, which sits in a contaminated zone that is closed to the public.
Tepco said it was investigating the cause of the current blackout, which it believes it has traced to the switchboard and attached cables. The company said it was readying a replacement switchboard in case it cannot fix the original one.
On Tuesday, the company was criticized for waiting three hours before revealing the outage to the public.
It said the failure also briefly cut off electricity to the command center at the plant, though power was quickly restored.
“These things are better if done quickly,” said the trade minister, Toshimitsu Motegi, whose ministry promotes the nuclear industry.
In a statement, the operator said the temperatures in the pool near the No. 4 reactor rose the highest since losing power, to 30 degrees Celsius, still well below the safety threshold of 65 degrees Celsius. Cooling systems at the No. 4 pool were restored Tuesday afternoon, the company said.
Tepco said the temporary blackout Monday also briefly cut off electricity to the command center at the plant, though power was quickly restored.
The No. 4 pool has been a source of concern before, largely because the building in which it is housed was almost totally destroyed during the original accident by a hydrogen blast caused by melting atomic fuel. The explosion left the pool exposed to the outside air. Tepco has been building a new, more protected pool to which it plans to move the spent fuel rods.
The company also said Tuesday that the loss of cooling water was manageable because temperatures in the fuel pools would have remained at safe levels for at least four days, and the plant also has backup systems.
