Bad news: another blast at the second reactor of Fukushima No.

CNN
[7:47 p.m. ET Monday, 8:47 a.m. Tuesday in Tokyo] Yukio Edano, Japan's chief Cabinet secretary, said he could not rule out the possibility of a meltdown at all three troubled reactors at the Fukushima Daiichi nuclear power plant in northeastern Japan.
While sea water was being pumped into the reactors in an effort to prevent further damage, "It cannot necessarily be called a stable situation," Edano said early Tuesday.
Kenneth Bergeron, a physicist who used to work at the U.S. Energy Department's Sandia National Laboratories in New Mexico, said that "the release of hydrogen and the fission products (suggests) these reactors have probably had fuel rods exposed for significant periods of time."
Edano's comments come amid news about an "explosive impact" that happened Tuesday morning at the No. 2 reactor.
Cooling has been a problem for days at reactors No. 1 and 3, because the earthquake and the tsunami damaged those reactors' cooling systems. But cooling problems at No. 2 began Monday, when a blast at the building that contains No. 3 - said to be caused by a buildup of hydrogen - damaged No. 2's cooling system.
[7:17 p.m. ET Monday, 8:17 a.m. Tuesday in Tokyo] More information about the new blast at the Fukushima Daiichi nuclear power plant in northeastern Japan: An "explosive impact" occurred Tuesday morning at the No. 2 reactor, a day after a hydrogen explosion rocked reactor No. 3, the plant's owner announced.
[7:09 p.m. ET Monday, 8:09 a.m. Tuesday in Tokyo] A blast has been heard at the site of the No. 2 reactor of the Fukushima Daiichi nuclear power plant, according to Japanese broadcaster NHK.
Kyodo
2320: A spokesperson from Tokyo Electric says said some staff have been evacuated from the site.
2316: Kyodo now says that the suppression pool may have been damaged at reactor 2.
Engineers explaining situation live on NHK:
http://www.livestation.com/channels/123-nhk-world-english
The suppression pool is what was damaged. Because of high pressure, there could be cracks that allow radiation to escape. The Japanese engineers are saynig that the contamination isn't strong enough cause harm to humans - but correcting the situation from here is "critical".