TOKYO — Workers have discovered new pools of radioactive water leaking from Japan’s crippled nuclear complex that officials think are behind soaring levels of radiation spreading to soil and seawater.
Crews also detected plutonium, a key ingredient in nuclear weapons, in the soil outside the complex, though officials insisted Monday that the finding posed no threat to public health.
Plutonium is present in the fuel at the complex, which has been leaking radiation for more than two weeks, so experts had expected to find traces once crews began searching for evidence of it this week.
The Fukushima Daiichi power plant was crippled March 11 when a tsunami spawned by a powerful earthquake slammed into Japan’s northeastern coast.
Since then, three of the complex’s six reactors are thought to have partially melted down, and emergency crews have struggled with everything from malfunctioning pumps to spikes in radiation that have forced temporary evacuations.
Tokyo Electric Power Co., which runs the complex, said plutonium was found in soil at five locations at the nuclear plant but that only two samples appeared to be plutonium from the leaking reactors. The rest came from years of nuclear tests that left trace amounts of plutonium in many places around the world.
The trouble comes if plutonium finds a way into the human body. The fear in Japan is that water containing plutonium at the station turns to steam and is breathed in, or that the contaminated water from the station migrates into drinking water.
While parts of the Japanese plant have been reconnected to the power grid, the contaminated water — which has now been found in numerous places around the complex, including the basements of several buildings — must be pumped out before electricity can be restored to the cooling system.
That has left officials struggling with two sometimes-contradictory efforts: pumping in water to keep the fuel rods cool and pumping out and then safely storing contaminated water.
Exactly where the water is coming from remains unclear, though many suspect it is cooling water that has leaked from one of the disabled reactors.
Hidehiko Nishiyama, a spokesman for Japan’s Nuclear and Industrial Safety Agency, called that balance “very delicate work.” He also said workers were looking for safe ways to store the radioactive water.
New readings showed ocean contamination had spread about a mile farther north of the nuclear site than before, but was still within the 12-mile radius of the evacuation zone. Radioactive iodine-131 was discovered offshore at a level 1,150 times higher than normal, Nishiyama told reporters.
