The situation at the Fukushima Daiichi power station is evolving rapidly this morning. Last night, even as operators took the drastic measure of filling reactor #1 with seawater to prevent a metldown, officials declared an emergency at the plant’s reactor #3. According to a statement from Tokyo Electric Power Company (TEPCO), the crisis arose after the injection of cooling water into the reactor core was interrupted. Reports from the broadcaster NHK paint a grim picture inside unit 3: Fuel elements appear to have been exposed, and hydrogen gas has been vented into the surrounding structure—raising fears of another explosion like the one that rocked unit 1 on Saturday. According to Chief Cabinet Secretary Yukio Edano, seawater and boric acid are now being injected into the unit to try and avert a meltdown. Meanwhile Kyodo news is reporting peak radiation levels of around 1,557 μSv (presumably per hour) around the plant.

At Fukushima Daini, the other main nuclear plant in the region, the International Atomic Energy Agency reports that power is still available to operate the cooling systems. TEPCO updates indicate that they are working to fully restore the cooling systems for a cold shutdown.

NHK is reporting that a second plant, at Onagawa is now reporting elevated levels of radiation. The plant has reported 21 μSv (again, presumably per hour), well above the 5 μSv reporting limit. Many refugees from the quake have taken shelter at the Onagawa reactor complex, but TEPCO says the health risk is minimal.

For full coverage of the Fukushima disaster, go to Nature’s news special.

Image: NHK