As a countermeasure against outflow of radioactive water into the sea near
the cooling water intake at unit 2 of Fukushima Daiichi Nuclear Power
Station, we have injected coagulant into the pit from April 5th and we
have observed stoppage of spilling of water from the crack on the concrete
lateral of the pit at 5:38 am, April 6th. (Reported on April 6th already)

Continued work from yesterday, we have put 6,000 litters of coagulant into
the breakage and surrounding ground after investigation of the leakage
route by putting tracer into the 9 holes drilled around electrical conduit
and the pit. As at 9:30 am, we have been observing there is no leakage of
water into the sea from the pit.

For the sake of completeness, we put further reinforcement for the
stoppage of leakage and consider countermeasure including continuous
injection of coagulant. We will also note the water level of turbine
building of unit 2 remain unchanged. We will further investigate if there
is any other leakage.

Facts  April 6, 5:38 am, Stoppage of leakage confirmed.

* pit: a shaft made of concrete
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(Reference) Facts
At around 9:30 am on April 2nd, we detected water containing radiation
dose over 1,000 mSv/h in the pit* where supply cables are stored near the
intake channel of Unit 2. Furthermore, there was a crack about 20 cm on
the concrete lateral of the pit, from where the water in the pit was out
flowing. At around 12:20 pm on April 2nd, we reaffirmed the event at the
scene.
We have implemented sampling of the water in the pit, together with the
seawater in front of the bar screen near the pit. These samples were sent
to Fukushima Daini Nuclear Power Station for analysis. (We already informed 
 on April 2nd, 2011) 

We also injected fresh concrete to the pit on April 2nd, but we could not
observe a reduction in the amount of water spilling from the pit to the
sea. Therefore, we started to inject the polymer (April 3rd). 

From 7:08 am to 7:11 am on April 4th, we put the tracer into the pit and
began an investigation of water flows. Additional tracer was put through
the two new holes drilled near the pit. At 2:15 pm, April 5th, it was
observed the water with tracer came out from the crack on the concrete
lateral of the pit. At 3:07 pm, April 5th, injection of coagulant from the
holes was initiated. (We already informed on April 5th, 2011) 

 Appendix: Status of countermeasure work (PDF 44.8KB)