The flooded basements of the Fukushima Daiichi unit 1, 2 and 3 turbine halls each contain 20,000 tons of radioactive water, according to electrical utility TEPCO.
TEPCO is preparing to start pumping water from the basement into each unit's turbine condensers, after having pumped the water already in the condensers into other tanks. Also, water will be pumped out of two shafts. However, the total storage space available on site appears to be only about half of what is needed to drain the three units' basements completely.
TEPCO has completed the installation of water curtains in the south breakwater of the Daiichi plant, to reduce the spread of radioactive water. In addition, a steel plate will be installed in front of the unit 2 screen, and silt fences for units 3 and 4 will also be installed.
Another magnitude 7.0 aftershock struck northern Japan on 11 April, after a previous aftershock struck 7 April, which knocked out external power at the Onagawa nuclear power plant for a time, forcing it to start its emergency backup diesel generators (this is contrary to what we reported at the time). TEPCO reported that the latest quake had no effect on its operations at Fukushima Daiichi.
In other news, a fire broke out at an electrical distribution box for radioactive sampling equipment at Fukushima Daiichi, but was extinguished. TEPCO said that the incident does not affect cooling operations.
The Japan Atomic Industrial Forum reports that parts of the area around the Fukushima Daiichi plant are likely to be evacuated. Currently, residents living between 20km-30km from the plant (12.5-18.5 miles) have been ordered to stay indoors, and consider leaving the area. The evacuation zone is likely to be expanded to cover areas where the total radiation exposure is expected to be greater than 20mSv. Those living less than 30km from the plant, but outside of the new evacuation zone, have been requested to be ready to stay indoors, or evacuate in an emergency.
FilesReactor-by-reactor, system-by-system summary from JAIF as of 13 April Fukushima-Daiichi parameters 13 April