Engineers at the crippled Fukushima Dai-Ichi nuclear campus in Japan have indicated the two-day power outage at the beleaguered campus may have been caused by a rat.

A spokesman for Tokyo Electric Power Co. (Tepco), the utility that runs the crippled plant, said that a six-inch rat was found dead Wednesday near an electrical switchboard. He said the rat may be linked to the power failure, but more investigation is needed to be sure.

Power was lost Monday in the cooling systems for four storage pools of spent nuclear fuel, depriving them of fresh cooling water.

Power was restored Wednesday at all affected facilities.

The water in the pools us used to cool the used fuel and acts as a shield to protect people and the environment.

While the power was out the temperature of the pools rose incrementally, but never exceeded the 149 Fahrenheit (65 Celsius) safety limit, said Tepco spokesperson Kenichi Tanabe.

Experts around Japan expressed doubts that anything serious would occur because of the power outage to the storage pools.

"Even if the water temperature goes up to 65 degrees Celsius, it would not cause anything critical right away, as long as the fuel bars are covered in water," said Akio Koyama, professor at Kyoto University's department of reactor safety management, in an Al Jazeera report.

"If the water levels get lower to the point where the fuel bars are exposed to the air, then we would have to worry."

Rats can often cause problems to electrical systems.

Last month in Tampa, Fl. a precautionary boil order on city water was in effect for two days after a rat chewed its way through a power line that caused a power outage at the city's water pumping station.