Oil spill into ocean from Fukushima Daiichi Units 5 and 6

The Associated Press has reported an oil spill into the ocean from atomic reactor units 5 and 6 at the devastated Fukushima Daiichi nuclear power plant in northeast Japan. The oil spill has occurred despite Units 5 and 6 being in a supposedly stable state of "cold shutdown," according to plant owner and operator Tokyo Electric Power Company (Tepco). Units 5 and 6 reactor cores just happened to be shut down for inspection and maintenance when the earthquake and tsunami struck on March 11th, facilitating their cooling since. Although Unit 4 was likewise shut down, and its reactor core emptied of nuclear fuel, its secondary containment building was destroyed by a hydrogen explosion, perhaps due to a high-level radioactive waste storage pool fire, or ingress of explosive hydrogen gas from the Unit 3 reactor via a venting system shared by the two units. In addition to the oil spill at Units 5 and 6, a "small" explosion has been reported at Unit 4. The biggest problems, however, remain the Units 1, 2, and 3 reactor cores, in states of meltdown at risk of burning through primary containment structures, as well as multiple high-level radioactive waste storage pools across the site, at risk of boiling dry, catching fire, and releasing catastrophic amounts of radioactivity directly into the environment, as they are not located within primary containment structures, and secondary containment buildings have been damaged or destroyed by massive hydrogen gas blasts. Japan Today reports that the oil leak was detected after bad weather hit the site. The Japan Times has reported that Tepco is speculating that two oil tanks, or connected pipes, which were being filled by a tanker at the time of the March 11 natural disasters, may have been damaged, and may even have been leaking oil ever since. The two tanks were moved 30 feet by the earthquake and/or tsunami; each tank could have contained as much as 1 million liters of heavy oil.