A new leak in a storage pool used to house radioactive water at Japan's Fukushima Daiichi facility is the latest problem to affect the battered nuclear campus.

The news comes days after two other tanks leaking radioactive water were reported.

The storage tank with the newest leak was being used to store the water that was transferred out of the other leaky tanks, the Associated Press reports, citing a Tokyo Electric Power Co (Tepco) spokesman.

Up to 120 tons of contaminated water is thought to have leaked from one of the tanks; a smaller amount is thought to have leaked from the other two. Tepco officials report that none of the leaked water is believed to have reached the ocean a half mile away from the site of the leaks.

About 400 metric tons of contaminated water is produced every day by the cooling systems in place to keep the nuclear fuel from overheating and causing a fission reaction. Radioactive cesium is reportedly removed from the water, but other radioactive materials remain in it as it is transferred to storage pools at the nuclear campus. 

Tepco has indicated that they will stop using the two most damaged of the leaking tanks as soon as they are empty, but plan to continue using the least damaged of the three tanks after the leak is repaired.

"We admit that the underground tanks are not reliable," Tepco spokesman Masayuki Ono said. "But we must keep using some of them that are relatively in good shape while monitoring them closely. We just don't' have enough tanks on the ground that can accommodate the water."

The tanks are vital for storage of the contaminated water used to cool melted fuel rods at the nuclear facility's reactors, which were damaged beyond repair due to the March 11, 2011 earthquake and tsunami that battered Japan's Tohoku region.

The Daiichi plant is being decommissioned, but has been beleaguered with troublesome problems. Last week a fuel storage pool lost power to its cooling system. Last month a portion of the plant was without power for two days after a rat chewed its way through power lines.