On June 8th, 2011 at approximately 6:10 pm, during an inspection of the 
underground emergency tanks*1 of High-voltage Start-up Transformer*2 
consisting of draining accumulated water from the tank's inside, a TEPCO 
employee verified the presence of oil that had leaked to the sea surface 
around the water discharge canal of Units 3 and 4. Presently, all water 
draining activities have been suspended. Furthermore, oil adsorption 
mattresses are being utilized to prevent the spread of oil and an oil fence
barrier is being prepared.
                                     (Previously announced on June 8, 2011)

At 9:50 pm on June 8th, installation of the oil fences was completed. 
Afterwards, it was confirmed that an extremely thin sheet of oil had spread
over the surface area of the sea enclosed by the oil fence.

Due to the March 11th earthquake, insulating oil from the high-voltage 
start-up transformer had leaked into the emergency underground tanks. On 
June 8th, during an inspection consisting of removing stored water from the
tank, 32 m3 of water mixed with insulating oil had leaked to the sea 
surface.
The maximum estimated amount of the insulating oil was 0.5 m3.

We will subsequently install and collect oil adsorption mattresses to 
prevent the oil from further spreading. We will also conduct a detailed 
investigation as to how water mixed with insulating oil leaked to the sea 
surface. 

*1 Emergency Underground Tank
A tank used to store the leakage of insulating oil from the High-voltage 
Start-up Transformer

*2 High-voltage Start-up Transformer
A transformer supplying offsite power to the power station during the 
plant's startup and shutdown.