At approximately 11:33 am on December 4, 2011, workers from cooperative
companies found that there was a puddle inside the barrier around the water
desalinations (the evaporative condensation apparatus (3A)) at Fukushima
Daiichi Nuclear Power Station.
Therefore, at approximately 11:52 am, we stopped the whole apparatus, then
the leakage stopped at approximately 0:14 pm.
Later, we conducted an investigation around the apparatus. At approximately
2:30 pm, we found that there was a crack in the base made of concrete,
from which water was leaking to the gutter outside the barrier.
Therefore, we conducted sampling surveys of the water leaked from the
barrier into the gutter, the water leaked from the apparatus, the water in
the general drainage canal, and the water around the outlet of the general
drainage canal. As a result, we concluded that the water leaked from the
apparatus flowed into the sea from the outlet of the general drainage
canal, which is 300m south of the discharge canal of Units 1 to 4 at
Fukushima Daiichi Nuclear Power Station.
We have piled sandbags around the barrier and in the gutter to prevent the
further outflow into the sea. In addition, the accumulated water inside
the barrier of the apparatus (approx. 15m3) has been collected by
facilities such as underwater pumps.
It is estimated that 150 liters of water which leaked from the barrier
flowed into the gutter and later flowed into the sea via the general
drainage canal. As a result, the total radioactivity flowed into the sea
was approximately 2.6 x 1010 Becquerel (provisional).
Regarding the influence of the leakage into the sea, if supposed an adult
eating the fish and the sea weeds around the discharge canal every day,
the effective dose is 0.0037 mSv/year, which is approximately 1/600 of
annual natural dose of an adult (2.4 mSV/year). Therefore, we assume
that there is little influence.
We deeply apologize to the inhabitants around the power station and every
one in the society that we let the water containing radioactive materials
flow into the sea to cause their worry and anxiety.
Though the evaporative condensation apparatus is stopped, the cesium
adsorption apparatus, the second cesium adsorption apparatus, and the
water desalinations (reverse osmosis membrane) are in operation. Purified
water sufficiently reserved, there is no influence to the water injection
into the reactor.
Hereafter, we will investigate the cause of the leakage and take
Appendix:Outflow of water leaked from the evaporative condensation
apparatus atFukushima Daiichi Nuclear Power Station(PDF 64.8KB)
Appendix:Results of sampling surveys of the water leaked from the
evaporativecondensation apparatus at Fukushima Daiichi Nuclear
Power Station(PDF 170KB)