At around 9:30 am on April 2nd, 2011, we found that there was water in the
shaft (concrete product) for storing power cables near the water intake for
Unit 2, that the airborne radiation of the water was over 1,000mSv/h and
that the water was out flowing into the sea from the crack (approx. 20 cm)
on the side of the shaft.
(Already announced on April 2nd)
With regard to the outflow of the water from around the water intake for
Unit 2, we injected chemical liquid and confirmed that the outflow of the
water stopped on April 6th.
(Already announced on April 6th)
To ensure the stoppage of the water outflow, we have been conducting grout
injection*1 and completed the work today (April 21st).
Also, to prevent the overflow of the contaminated water in the trench, we
will continuously implement further countermeasures such as blocking of
The amount of the high level radioactive water flowed out from the screen
on the turbine building side of Unit 2 and its total amount of
radioactivity are estimated to be approximately 520 m3 and approximately
4.7*1015 Becquerel respectively, assuming that the water flowed out at a
certain flow rate from April 1st to 6th.
As a countermeasure against this water outflow and to prevent and minimize
the spread of the radioactive fluid, we installed iron plates at the screen
room of Unit 2, silt fences in front of the screen rooms of Unit 1-4, 62
large sandbags around the south pier of the power station, and 10 sandbags
including radiation absorber (zeolite) in front of the screen rooms of Unit
1-4. We will plan further countermeasures such as the installation of steel
sheet piles*2 to the south pier of the power station and the installation
of equipments for radiation absorption.
In order to ensure the prevention of the dispersion of contaminated water
in the turbine building, we will steadily proceed with the transfer of the
contaminated water to the Centralized Radiation Waste Treatment Facility
and tanks and the treatment of the water.
We will continuously follow up the situation by monitoring the radioactive
substances and conducting sampling surveys inshore and offshore.
*1 grout injection: a construction method to stop water flow by injecting
liquid glass or cement-based materials
*2 steel sheet piles: steel plates installed under the ground to prevent
the out flow of soil or water
Appendix:Outflow of radioactive water from the concrete crack near intake
canal for Unit 2 of Fukushima Daiichi Nuclear Power Station
Reference-1:Evaluation method of volume of discharge(PDF 65.5KB)
Reference-2:Photo(taken at approx. 2:20 pm on April 5th, 2011)(PDF 132KB)
Reference-3:Counter measurement for preventing diffusion of liquid
contained radioactive material(PDF 132KB)
Reference-4:Sampling survey points at 3km, 8km and 15km from offshore