Two brave souls entered reactor #1 to get an ocular on the basement situation today and confirmed that water levels are indeed at least 4 meters deep. Tepco is preparing to set up a cooling system that will pump water out of the basement, decontaminate it, and send it back into the reactor.
The idea is to reduce the need to pump high volumes of fresh water from outside that just winds up leaking out of the reactor and into other undesirable locations within the plant. The two employees spent "about one hour" making observations and gathering info, which is about the longest period of time i can remember a person spending in any of the units as of late.
The article also mentions that "4 other workers later took over and spent about 90 minutes on the ground floor using a gamma camera to measure the spread and densities of radiation." I get the sense that Tepco is getting as serious as cancer about making progress, but found it unusual that they reported the amounts of time their employees spent inside the reactor without providing associated exposure information.
This data is usually provided to the media. For example, an article on May 5th indicated that two workers installing a ventilation system in that same reactor stayed for 25 minutes and received 2 milliSieverts. Todays employees were exposed for 1-1½ hours. They probably received a manageable dose, but based on an exposure chart for unit 1 released this past weekend (above left), radiation levels measured at different locations within the unit were still considerably high. Hopefully, Tepco will clarify how much exposure these guys actually got.
Read the story here