Explosion at Japan's Fukushima Daiichi Nuclear Power Station

Photo credit: NTV Japan, via APTN, via Associated Press

A major explosion blew off the roof and crumbled the walls of one of the buildings at the Fukushima Daiichi Nuclear Power Station Saturday afternoon.  The plant is located in the coastal town of Okuma in the Fukushima Prefecture, 150 miles north of Tokyo.  About 11,00 people live in Okuma.  Watch the BBC video of the explosion here.

The emergency at the Daiichi plant began shortly after the earthquake struck on Friday afternoon. Emergency diesel generators, which had kicked in to run the reactor's cooling system after the electrical power grid failed, shut down about an hour after the earthquake. There was speculation that the tsunami knocked the generators out of service.

Twenty hours later, the plant was operating in a battery-controlled cooling mode. Tokyo Electric said that by Saturday morning it had installed a mobile generator at Daiichi to ensure that the cooling system would continue operating even after reserve battery power was depleted. Even so, the company said it was considering a "controlled containment venting" in order to avoid an "uncontrolled rupture and damage" to the containment unit.

Although the cause of the explosion is not yet certain, it would appear that an "uncontrolled rupture" has indeed occurred and perhaps the nuclear fuel is exposed.  Let us hope that this will not develop into a melt-down.

About 45,000 people within a 6-mile radius of the plant have be told to evacuate.  One wonders how quickly evacuation is possible in an area already ravaged by earthquake and tsunami.  My heart goes out to the people of Japan, but especially to my friend Chiaki and her family.