This article is from the source 'nytimes' and was first published or seen on . It last changed over 40 days ago and won't be checked again for changes.

You can find the current article at its original source at http://www.nytimes.com/2013/04/06/world/asia/rat-chase-again-bedevils-fukushima-nuclear-plant.html

The article has changed 8 times. There is an RSS feed of changes available.

Version 0 Version 1
Rat Chase Again Bedevils Fukushima Nuclear Plant Rat Chase Again Bedevils Fukushima Nuclear Plant
(about 3 hours later)
TOKYO — Workers at the stricken Fukushima nuclear power plant who were installing wire nets Friday to keep rats away from a vital cooling system instead tripped up that system, causing it to fail for the second time in weeks.TOKYO — Workers at the stricken Fukushima nuclear power plant who were installing wire nets Friday to keep rats away from a vital cooling system instead tripped up that system, causing it to fail for the second time in weeks.
The spent fuel pool at the site’s No. 3 reactor went without fresh cooling water for almost three hours Friday afternoon, said the plant’s operator, the Tokyo Electric Power Company, known as Tepco. The spent fuel pool at the site’s No. 3 reactor went without fresh cooling water for almost three hours on Friday afternoon, said the plant’s operator, the Tokyo Electric Power Company, or Tepco.
Cooling was restored by late evening on Friday, and there was no imminent danger to the 566 nuclear fuel rods stored in the pool, according to Tepco. It would have taken at least two weeks for the pool to have risen above the safe level of 149 degrees Fahrenheit, Tepco said. Cooling was restored by late evening on Friday, and there was no imminent danger to the 566 nuclear fuel rods stored in the pool, according to the company. It would have taken at least two weeks for the pool to have risen above the safe level of 149 degrees Fahrenheit, Tepco said.
Still, the recent power failures have raised concerns over continued vulnerabilities at the plant two years after a large earthquake and tsunami knocked out its vital cooling systems, triggering multiple fuel meltdowns and forcing the evacuation of 160,000 people.Still, the recent power failures have raised concerns over continued vulnerabilities at the plant two years after a large earthquake and tsunami knocked out its vital cooling systems, triggering multiple fuel meltdowns and forcing the evacuation of 160,000 people.
The debris-strewn plant still relies on makeshift cooling systems, some of which were hastily put together in the accident’s frantic aftermath. The spent fuel pools, which hold far more radioactive material than the reactor cores, have been a particular source of concern.The debris-strewn plant still relies on makeshift cooling systems, some of which were hastily put together in the accident’s frantic aftermath. The spent fuel pools, which hold far more radioactive material than the reactor cores, have been a particular source of concern.
A blackout disabled cooling at four fuel pools last month, an incident the company blamed on a rat that may have gnawed on power cables and triggered a short circuit. The rat died, and engineers later found its scorched body in a damaged switchboard. A blackout disabled cooling at four fuel pools last month, an incident the company blamed on a rat that may have gnawed on power cables and triggered a short circuit. Engineers found its scorched body in a damaged switchboard.
Tepco has since installed mouse traps at the sprawling site and promised to plug holes though which rats and other rodents might enter buildings and gnaw on important equipment. It has also promised to speed up work to install backup power cables to the fuel pools.Tepco has since installed mouse traps at the sprawling site and promised to plug holes though which rats and other rodents might enter buildings and gnaw on important equipment. It has also promised to speed up work to install backup power cables to the fuel pools.
But Friday afternoon, four workers using wire meshing to seal a space around electric cables triggered a ground fault, or the accidental flow of current to the ground. None of the workers were injured, but the ground fault shut off electricity to the cooling system at the No. 3 reactor fuel pool.But Friday afternoon, four workers using wire meshing to seal a space around electric cables triggered a ground fault, or the accidental flow of current to the ground. None of the workers were injured, but the ground fault shut off electricity to the cooling system at the No. 3 reactor fuel pool.
“We were installing wire nets to keep the rats out. But the end of one of the wires may have momentarily come into contact with a live terminal,” said Masayuki Ono, general manager at Tepco’s Nuclear Power and Plant Siting Division. “The next moment, there were sirens.”“We were installing wire nets to keep the rats out. But the end of one of the wires may have momentarily come into contact with a live terminal,” said Masayuki Ono, general manager at Tepco’s Nuclear Power and Plant Siting Division. “The next moment, there were sirens.”