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 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: 4.2×101 Bq/cm3, cesium 137: 7.4×101 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. At 6:20 PM on the same day, accumulated water transfer from Unit 2 Turbine Building basement to Unit 3 Turbine Building basement was stopped in order to identify the leakage location. As a result, the joint part of pressure hose on the aisle which was used when preparing for a pressure test was found to be detached. At 7:42 PM, accumulated water transfer from Unit 2 Turbine Building basement to Unit 3 Turbine Building basement was restarted. The leakage amount was reevaluated to be 15m3 (Approx. 750m2 x 20mm (depth)).
-At 10:55 PM on December 11, Unit 1 reactor injection water amount was adjusted as follows since the amount had decreased. Feed water system: Increased from approx. 2.1m3/h to approx. 2.5m3/h, Reactor core spray system: Maintained at approx. 2.5m3/h.
-At 2:02 PM on December 12, Unit 3 spent fuel pool cooling was suspended in order to install additional valves and inspect the check valves in the spent fuel pool alternative cooling system. The cooling will be suspended until December 18. The pool water temperature was approx. 11.0℃ when the cooling was stopped. The pool water temperature increase rate is approx. 0.16℃/h and the amount of temperature increase during cooling suspension is estimated to be approx. 24℃. There is no problem with the pool water temperature control considering the sufficient margin to the maximum allowed temperature (65℃).
[Fukushima Daini Nuclear Power Station]
・Unit 1 to 4: Shutdown due to the earthquake.
Past Progress (As of 3:00 pm, on December 12, 2012) (PDF 627KB)
Past Progress (From March 12, 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.