Friday, April 08, 2011

Friday Update

No nuclear power plants were seriously damaged in the heavy aftershock that rattled northeastern Japan Thursday, the International Atomic Energy Agency reported. The epicenter of the 7.1 magnitude earthquake was 12.5 miles from the Onagawa nuclear power plant and about 75 miles from the Fukushima Daiichi site, where engineers are working to restore fuel cooling capabilities that were lost in the original March 11 temblor and tsunami.

Fukushima Daiichi
At Fukushima Daiichi, the injection of cooling water into the reactor pressure vessels of reactors 1, 2 and 3 continued Friday, along with injection of nitrogen gas into the containment vessel of reactor 1. The nitrogen will prevent possible ignition of hydrogen that may be accumulating in the containment. Tokyo Electric Power Co. is continuing the discharge of low-level radioactive water from a waste storage tank into the Pacific Ocean to make room for highly radioactive water pooled in the basement of the reactor 2 turbine building.

Isolated spikes in radiation inside reactor 1 containment have been associated with possible fuel movement during the April 7 aftershock, but radiation dose rates elsewhere at the site continue to decline.

The government lifted restrictions on shipments of raw milk and some produce from municipalities near Fukushima Daiichi. An official said tests show the food is safe to consume.

The aftershock of April 7 caused minimal, if any, disruption at other nuclear power plants.

Fukushima Daini
All reactors have been shut down since the March 11 earthquake. There have been no changes in the radiation readings at on-site monitoring posts.

All reactors have been safely shut down since the March 11 earthquake. Reactor cooling operations continue with power from the electric grid. A small amount of water was spilled from the spent fuel storage pools of all three reactors. Workers also found water leaks in several locations at the plant. Cooling for a spent fuel pool was lost briefly. There was no change in off-site radiation levels.

Tokai Daini
The plant has been shut down since the March 11 earthquake. No abnormalities have been observed.

The plant was shut down for maintenance at the time of the aftershock. Fuel had been removed from the reactor core and stored in the spent fuel pool. Off-site power was lost in the aftershock, and the plant operated for a few hours on backup generators. Later, off-site power was restored.

Reactors 1 and 2 were in operation at the time of the aftershock. Hokkaido Electric Power Co. reduced the generating power to 90 percent of capacity.

Rokkasho Reprocessing Plant
Off-site electric power was lost in the aftershock. Backup power supply to the site is operating the cooling systems.

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