For those looking for hope amidst the nuclear threat afflicting post-Tsunami Japan, there are some glimmers of possibly positive developments to report from the Fukushima Daiichi nuclear power complex:

• Japanese authorities say that water canons and aerial water drops from helicopters may have stabilized reactor 3 and its fuel pool (video below). Of Fukushima Daiichi’s six reactors this was viewed as the most dangerous. A hydrogen explosion may have breached reactor 3’s primary containment vessel last week, and spent fuel stored in its cooling pool was thought to be at risk of explosion.
• Diesel generators are now providing power to reactors 5 and 6, raising hope that their cooling systems can be reactivated to bring down dangerously high temperatures in their spent fuel pools.
• Plant operator TEPCO has laid a powerline to reactor 2. As with the reactor 5 & 6 fuel pools, the hope is to reactivate systems to cool reactor 2’s damaged reactor core and its spent fuel pool. The cooling systems, however, may be inoperable following hydrogen explosions and fires at adjacent reactors last week.

On the downside, there is little concrete information on the state of reactor 4’s spent fuel pool, said to be empty by the chair of the U.S. Nuclear Regulatory Commission on Wednesday. An official with the International Atomic Energy Agency in Vienna reported this morning that they still lacked, “reliable validated data on water levels and temperatures at the spent fuel pools at Units 3 and 4.”

Japanese officials have, meanwhile, detected dangerous levels of radioactive iodine-131 in tap water sampled 45 kilometers northwest of Fukushima Daiichi. Iodine is also showing up in milk in Fukushima province, and in vegetables over 65 kms away in a neighboring province. Worse still, the government measured the highest iodine levels in drinking water on Thursday, but waited until today to disclose it.

Separately, Japan’s Nuclear and Industrial Safety Agency has upgraded its official rating of the Fukushima Daiichi incident to level 5 on the 7-level international nuclear incident severity scale, putting it on par with the partial meltdown at Three Mile Island in 1979 that capped reactor construction in the U.S. The head of France’s Nuclear Safety Authority has insisted since Tuesday that Fukushima Daiichi is a level 6 incident, just one step below the 1986 Chernobyl meltdown that shook European confidence in nuclear energy.

Japanese Ministry of Defense video of water canon missions on reactor 3: