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 4:30 PM on December 13, a TEPCO employee found water dripping (about 2 drops per second) from the air conditioning duct installed on the upper part of aisle on the first floor of Unit 4 Waste Treatment Building. The area affected by the water dripping is approx. 2m x 2m x 1mm (depth) on the floor of Unit 4 Waste Treatment Building first floor, and the amount of water is estimated to be approx. 2L. The water has not flowed to the outside of the building since it flowed into the floor funnel (connected to the basement) from Unit 4 Waste Treatment Building and the structure of the first floor surface is similar to a dam. The radioactivity density analysis results of the dripped water are as follows. It has been confirmed that the detected densities are lower than those of the accumulated water in the Turbine Building basement (103-104 Bq/cm3).
Cesium 134: approx. 4.2x101 Bq/cm3
Cesium 137: approx. 7.2x101 Bq/cm3
Considering that cobalt 60 and hydrazine were not detected in the water, it has been confirmed that the composition of the dripped water is different from that of Unit 4 spent fuel pool water*.
*Composition of Unit 4 spent fuel pool water (Sampled on December 3, 2012)
Cobalt 60: Approx. 2.5x101 Bq/cm3
Hydrazine: Approx. 3ppm
As a result of investigating the condition and the duct where water was dripping from on December 14, it was found that water was dripping from the joint part of the duct and that there was a damage on the outdoor air conditioning duct located in the upper part of the building which is connected with the air conditioning duct in the upper part of the aisle on the first floor of the Waste Treatment Building where the incident occurred. Based on the findings and the radioactivity analysis results of the dripped water, the water dripping from the duct joint has been identified to be rainwater which flowed into the duct from the damaged part of the outdoor duct. At 3:30 PM, the amount of water dripping from the duct was decreased to 1 drop every 3 seconds. As the duct is currently not in use, a rainwater protection measure will be considered to prevent recurrence.
[Fukushima Daini Nuclear Power Station]
· Unit 1 to 4: Shutdown due to the earthquake.
Past Progress (As of 3:00 pm, on December 15, 2012) (PDF 629KB)
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.