TOKYO – A rat causing a power outage by short-circuiting a temporary switchboard. Another blackout occurring as workers install anti-rat nets. Holes in the linings of huge underground tanks leaking radioactive water.

Japan’s crippled Fukushima Dai-ichi nuclear power plant has run into multiple problems recently that highlight its precarious state more than two years after its reactors melted down in the wake of a devastating earthquake and tsunami.

A makeshift system of pipes, tanks and power cables meant to carry cooling water into the melted reactors and spent fuel pools inside shattered buildings remains highly vulnerable, Nuclear Regulation Authority chairman Shunichi Tanaka acknowledged Wednesday.

“Fukushima Dai-ichi is still in an extremely unstable condition, there is no mistake about that,” Tanaka said at a weekly meeting of the regulatory body’s leaders.

“We cannot rule out the possibility that similar problems might occur again. Whenever a problem occurs, it halts the plant’s operations and delays the primary goal of decommissioning the plant.”

The problems have raised doubts about whether the plant can stay intact through a decommissioning process that could take 40 years, prompting officials to compile risk-reduction measures and revise decommissioning plans. The regulatory watchdog said Wednesday that it was increasing the number of inspectors from eight to nine to better oversee the plant.

Just over the past three weeks, there have been at least eight accidents or problems at the plant, the nuclear watchdog said.

The first was March 18, when a rat got into an outdoor switchboard – which was sitting on a pickup truck – powering the makeshift cooling system and several other key parts of the plant, causing a short-circuit and blackout that lasted 30 hours in some areas of the plant. Four storage pools for fuel rods lost cooling during the outage, causing Tokyo Electric Power Co., the plant’s operator, to acknowledge that it had added backup power only to the reactors, despite repeated concerns raised over a pool meltdown.

The cause of the outage wasn’t clear at the time, but TEPCO later released a photo of the electrocuted rat, which had fallen on the bottom of the switchboard outhouse.

Two weeks later, a new water processing machine designed to remove most radioactive elements temporarily stopped after a worker pushed a wrong button.

The next day, one of the fuel storage pools lost power again for several hours when part of a wire short-circuited a switchboard while an operator installed anti-rat nets.

TEPCO reported three other minor glitches on the same day, including overheating of equipment related to boron injection to the melted reactors.

In the latest development, three of the plant’s seven underground tanks are leaking. TEPCO reported the first leak early Saturday, hours after the plant’s second power outage. Within days, the damage spread to three tanks, paralyzing the plant’s storage plans for contaminated water.

TEPCO says none of the about 120 tons of radioactive water that leaked was believed to have reached the nearby Pacific Ocean.

 

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