At around 1:05 am on April 5, 2012, we found the increase in the amount of concentrated water in transfer piping between water desalinations device and concentrated water storage tank in water desalinations (reverse osmosis membrane) in Fukushima Daiichi Nuclear Power Station.  Since there may be water leakage in the water desalinations, at around 1:10 am on the same day, we stopped operating the device.  At around 1:45 am, to prevent from water leakage, we closed both sides of bulbs located at the end of the piping (pressure-proof hose) that connects water desalinations (reverse osmosis membrane) and concentrated water storage tank.  After then, TEPCO worker checked the water desalinations (reverse osmosis membrane), and at 1:50 am, we found the leakage of water at the piping between water desalinations (reverse osmosis membrane) and concentrated water storage tank.  However, since we had closed the bulbs, the leakage stopped at 2:20 am.

Until now, our investigation found that there was an increase in concentrated water flow for 7 minutes (between 0:06 to 0:13 am) on the same day and there were three short time start-and-stop operations of the device between 0:50 and 1:10 am.  With is findings, we estimate that there is possibility that amount of 12m3 of concentrated water was discharged to sea through U-shaped gutter and drain.  Also, we found that the leakage is from lagging material of pressure-proof hose, and so we took away it and confirmed that the hose is off the connecting flange.

The leaked water may be discharged to nearby general drain.  Therefore, we sampled the leaked water, water in drains and sea water nearby drains placed 300m from south side of water exit of 1-4 units of Fukushima Daiichi Nuclear Power Station.  The result is that γ nuclide is detected from leaked water and water in the drain, but the sea water is under the limit of detection.   We are going to analyze all βnuclides.

We deeply apologize again for serious anxiety and nuisance of the people who live in the nearby area and the people of the society.

At this moment, the water desalinations (reverse osmosis membrane and evaporative concentration apparatus) are not in service. However, because we have much treated fresh water, it does not affect water injection to the reactors.

 

Appendix1: Water leakage point at transfer piping between water desalinations (reverse osmosis membrane) and concentrated water storage tank in Fukushima Daiichi Nuclear Power Station (PDF 23.6KB)
Appendix2: Water leakage point at concentrated water storage tank area between water desalinations (reverse osmosis membrane) and the concentrated water storage tanks in Fukushima Daiichi Nuclear Power Station (PDF 470KB)
Appendix3: Result of the sampling regarding the water leakage at transfer piping between water desalinations (reverse osmosis membrane) and concentrated water storage tank in Fukushima Daiichi Nuclear Power Station (PDF 79.5KB)