On June 8th, 2011, during the patrol of emergency underground tanks of 
High-voltage Start-up Transformer*, when discharging storage water in the 
tank, approximately at 6:10 pm a TEPCO employee has found and confirmed oil 
leakage to the sea around the water discharge canal of Unit 3 and 4, 
Fukushima Daini Nuclear Power Station. We reported the issue to Futaba 
Wide-area Fire Headquarters and Fukushima Coastguard Office.

Currently we stopped discharging the storage water. And we put oil 
adsorption mattress to prevent oil spreading and preparing installing oil 
fences.

The cause of the leakage and its details such as volume and status are 
under investigation.

*High-voltage Start-up Transformer
A transformer supplying offsite power into the power station when start-up 
and shut-down of the plant. 

Appendix: Oil leakage found around water discharge canal of Unit 3, 4(PDF 153KB)