Corporate Information

Press Release (Apr 21,2011)
Fukushima Daiichi Nuclear Power Station Unit 2:Countermeasures to stop the outflow of contaminated water and the water amount flowed out into the sea
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 shaft.

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 
                                                              (PDF 93.5KB) 
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 
                                                              (PDF 136KB) 
back to page top

to TOP