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)
At 5:38 am on April 6th, we observed the stoppage of the water spilling
from the crack on the concrete lateral of the pit. Details of the
situation will be announced after checking the blockage of the water
We will continue the countermeasure in order to prevent further outflow
of high level radioactive materials to the ocean.
*pit: a shaft made of concrete