Unit 1 airlock opened

10 May 2011

Workers for Japanese electrical utility TEPCO have opened the airlock of the damaged unit 1 reactor building at Fukushima Daiichi, and ventured inside the reactor building.

Inside Fukushima Daiichi unit 1
A worker on the north side of the second floor, pictured on 9 May 2011

The work is part of a plan to flood the unit 1 vessel, with a goal of stabilising the unit. Workers need to install new water level gauges, and other perform other preparations inside the unit. On 5 May workers entered the reactor to install a temporary duct system that filtered the reactor air, and reduced the amount of radioactive airborne dust in the plant. Radioactivity declined from 4.8 Bq/cm3 on 26 April to 0.0197 Bq/cm3 on 7 May. The airlock was opened on 8 May. TEPCO said that the radioactive effect of opening the airlock was negligible.

On 9 May, seven TEPCO employees, two NISA inspectors and 21 contractors entered the reactor building to measure radioactivity levels.

TEPCO plan for Fukushima Daiichi unit 3 cooling line change
TEPCO will re-route cooling water that reaches the reactor via the core spray line, to a new connection to the feedwater line

In other news, TEPCO has launched a plan to change the routing of cooling water to the Fukushima Daiichi unit 3 reactor. It had previously been injecting water into the fire extinguisher line to the condensate water makeup line to the core spray line. It now plans to inject water to the reactor via the feedwater line. It said that the change would improve reliability. To make the change, it was already scheduled to start work draining the feedwater line. It also needs to block off the line from the condensate return system, and install a new line from the turbine building, regulated by a valve. It expects the new line to be in service by 12 May.

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