The situation at the Fukushima Daiichi nuclear complex is getting worse in many ways, but better in some ways. Here’s a quick roundup.
Energy Secretary Steven Chu said that roughly 70 percent of the core of reactor number 1 suffered severe damage. In other words, it came very close to a total meltdown. But things appear now to be stabilizing:
Mr. Chu, a Nobel laureate in physics, suggested that the worst moments of the crisis appeared to be receding, saying that the best information the United States had received from the Japanese authorities indicated that water was once again covering the cores of the stricken reactors and that pools of spent fuel atop the reactor buildings were “now under control.”
Tepco announced that there is a crack in the concrete pit of reactor number 2 that is leaking radiation into the ocean from a crippled reactor:
Tokyo Electric Power Co (TEPCO) said it had found a crack in the pit at its No.2 reactor in Fukushima, generating readings 1,000 millisieverts of radiation per hour in the air inside the pit.
Reuters noted that workers were attempting to plug the crack with concrete, but were facing challenges:
Public broadcaster NHK said late on Saturday that water was preventing the concrete from hardening and the pit was still leaking.
As previously noted, CNN reported:
Authorities in Japan raised the prospect Friday of a likely breach in the all-important containment vessel of the No. 3 reactor at the stricken Fukushima Daiichi nuclear power plant, a potentially ominous development in the race to prevent a large-scale release of radiation.
The New York Times pointed out:
A senior nuclear executive who insisted on anonymity but has broad contacts in Japan said that there was a long vertical crack running down the side of the reactor vessel itself. The crack runs down below the water level in the reactor and has been leaking fluids and gases, he said.
“There is a definite, definite crack in the vessel — it’s up and down and it’s large,” he said. “The problem with cracks is they do not get smaller.”
And NHK notes that a giant crane fell over and probably crushed spent fuel rods at in Fukushima reactor number 3, which contain a plutonium-uranium mix:[youtube http://www.youtube.com/watch?v=wAEixbcPhG4]
(starting around 1:40 into video).
Nuclear engineer Arnie Gundersen notes that the spent fuel rods in reactor number 4 have no water, and the rods are exposed:
Aerial Views of the Destruction
As can be seen from the following aerial photograph, there is severe damage at several of the reactors (click the images for larger, high-res versions):
Localized nuclear reactions (“re-criticalities”) have re-started at Fukushima causing “blue flashes” above the plant:[youtube http://www.youtube.com/watch?v=qRoIpMNTbcQ]There is no indication that widespread nuclear reactions will re-start.
Greenpeace has measured very high levels of radiation some 40 killometers from Fukushima:[youtube http://www.youtube.com/watch?v=I3eBMiJKit0]Update: See also the following discussion by Gundersen of the meaning of re-criticality in the core of reactor number 1: [vimeo http://www.vimeo.com/21881702 w=400&h=226]