The outage was one of several that recently plagued the facility, which underwent extensive repairs since the devastating earthquake and tsunami in March 2011 that triggered a nuclear disaster there, CNN reported.
The cause of Friday's outage, which lasted several hours, was not reported.
Last month, power outages at the nuclear facility were blamed on rat activity shorting out a switchboard, Kyodo reported. Officials said the temporary loss of power did not trigger any known release of radioactive material.
Metal panels will be installed around the cooling system as a barricade, a Tepco spokesman said.
The tsunami knocked out power and coolant systems at the nuclear plant, leading to meltdowns in three reactors and resulting in the worst nuclear accident since Chernobyl, as the crippled Fukushima reactors belched radioactive particles into the environment.
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