Due to the Tohoku-Chihou-Taiheiyou-Oki Earthquake which occurred on March 11, 2011, TEPCO's facilities including our nuclear power stations have been severely damaged. We deeply apologize for the anxiety and inconvenience caused.
With regard to the accident at Fukushima Daiichi Nuclear Power Station, on April 17, 2011, we have compiled the roadmap towards restoration from the accident and on July 19 we accomplished the Step1 target "Radiation dose is in steady decline". Then on December 16 we confirmed the accomplishment of the Step 2 target "Release of radioactive materials is under control and radiation doses are being significantly held down".
In addition, on December 21, 2011, we have compiled the "Mid-to-long-Term Roadmap toward the Decommissioning of Fukushima Daiichi Nuclear Power Units 1-4, TEPCO".
In addition to the maintenance of the plant's stable condition, we will implement Mid-to-Long Term countermeasures towards the decommissioning of Fukushima Daiichi Nuclear Power Units 1-4 to enable evacuees to return to their homes as soon as possible and reduce the anxiety of the people in Fukushima and the whole nation as soon as possible.
Below is the status of TEPCO's nuclear power stations (Fukushima Daiichi and Fukushima Daini).
* The updates are underlined.
[Fukushima Daiichi Nuclear Power Station]
·Unit 1 to 4: Abolishment (April 19, 2012)
·Unit 5 to 6: Outage due to regular inspections before the earthquake
-At 10:55 AM on December 10, a cooperative company employee on patrol found water leakage in the temporary warehouse of the desalination system (reverse osmosis membrane) 3. At 10:55 AM on the same day, the desalination system 3 was suspended and the leakage was confirmed to have stopped. The area affected by the leakage was approx. 4m x 8m x 3mm. The leaked water remains in the dam and has not flowed out of the temporary warehouse. The radioactivity density analysis results of the leaked water are as follows.
Cesium 134: 3.9x100 Bq/cm3, cesium 137: 7.1x100 Bq/cm3, Manganese 54: 9.8x10-2 Bq/cm3
Upon investigation, the cause of the leakage was assumed to be the header joint part coming off due to the cassette drain valve opening a little when touched. As a countermeasure, the valves similar to the concerned valve installed in the desalination system (reverse osmosis membrane) 3 have been fixed to be closed at all times with warning signs installed nearby on December 11. At 1:32 PM on the same day, the system was restarted.
-At around 11:08 on December 11, a cooperative company employee found a water puddle on the aisle in the west side of Unit 3 Turbine Building first floor. At around 11:30 AM on the same day, the leakage was confirmed to have stopped as the filtrate water line valve was closed to check for leakage in the newly installed polyethylene pipe. The entire aisle was affected by the leakage (approx. 5m x 90m x 10-30mm (depth)) and the leakage amount currently estimated is approx. 13m3. The leaked water flowed into the feed water heater room on the first floor of the Turbine Building and then into the funnel (pipe going down to the basement), and it has not flowed to the outside of the building. The radioactivity density analysis results of the leaked water were as follows.
Cesium 134: 4.2x101 Bq/cm3, cesium 137: 7.4x101 Bq/cm3
The densities are lower than that of the accumulated water in the building basement (103 - 104Bq/cm3). Based on the radioactivity density analysis results and the fact that no leakage was found in the reactor water injection system in the building, the leaked water has been assumed to be the filtrate water used for the fire hydrant. Considering that a pressure hose is connected to the fire hydrant near the large equipment hatch in order to supply water used in the pressure test for the accumulated water transfer pipe and the hose goes through the aisle where the leakage occurred, the leakage location is estimated to be the pressure hose.
[Fukushima Daini Nuclear Power Station]
·Unit 1 to 4: Shutdown due to the earthquake.
Past Progress (As of 3:00 pm, on December 11, 2012) (PDF 619KB)
Past Progress (From March 11, 2011 to December 31, 2011) (PDF 523KB)
* Revised past progress
The aforementioned attachments are only available in Japanese.
We apologize for any inconvenience this may cause.