TOKYO — Cooling systems were restored for four fuel-storage pools at Japan’s tsunami-damaged nuclear plant, more than a day after a power outage halted the supply of fresh cooling water and raised concerns about the safety of the facility, which still relies on makeshift equipment.
Tokyo Electric Power Co. said the cooling system at the last pool at the Fukushima Dai-ichi plant was repaired early Wednesday. It said pool temperatures were well within safe levels and the reactors were unaffected.
TEPCO spokesman Yoshikazu Nagai said workers were still trying to determine the cause of the cooling failure, which began when a brief power blackout hit the plant Tuesday evening.
About 50 workers in hazmat suits and full-face masks were mobilized to fix the cabling to three switchboards that were suspected of involvement in the problem. TEPCO also prepared a backup system in case the repairs did not fix the issue and ‘‘worse comes to worst,’’ company spokesman Masayuki Ono said earlier Tuesday.
A massive earthquake and tsunami on March 11, 2011, caused extensive damage to the plant. Massive radiation leaks at that time contaminated air, water, and soil around the plant, causing some 160,000 residents to evacuate.
The latest power outage was a test for TEPCO to show if it has learned anything from the disaster. TEPCO, which has faced repeated cover-up scandals, was slammed by local media Tuesday for waiting hours to disclose the blackout.
Ono acknowledged the plant was vulnerable.
‘‘Fukushima Dai-ichi still runs on makeshift equipment, and we are trying to switch to something more permanent and dependable, which is more desirable,’’ he said. ‘‘Considering the equipment situation, we may be pushing a little too hard.’’
Ono said the utility did not immediately try to switch to a backup cooling system because doing so without finding and fixing the cause could lead to a repeat of the problem.
There is a backup cooling system but no backup outside power source.