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

- A worker of TEPCO confirmed a decrease in the amounts of water injection for Unit 1 - 3 reactors as below at 3:00 PM on August 30 at the regular data check.

Unit 1: The amount of water injection decreased from 4.9m³/h (at 2:00 PM) to 4.0m³/h.
(The required amount of water injection: 4.3m³/h.)

Unit 2: The amount of water injection decreased from 7.0m³/h (at 2:00 PM) to 5.5m³/h.
(The required amount of water injection: 6.1m³/h.)

Unit 3: The amount of water injection decreased from 7.0m³/h (at 2:00 PM) to 5.6m³/h.
(The required amount of water injection: 6.1m³/h.)

The shift supervisor judged that the condition did not satisfy the "Operational Requirements" defined by the Technical Specification" for Unit 2 at 3:00 PM, for Unit 3 at 3:05 PM and for Unit 1 at 3:07 on the same day. Though we attempted to increase the water injection amounts at the site, the amounts kept decreasing. The water injection amounts were continuously monitored and have been adjusted as necessary. As a result of site investigation, no water leakage from the reactor injection system was found. Upon checking the regular reactor injection water pump on the hill (B) and (C) which were in operation when the injection amounts started decreasing, no air intrusion was found in the pumps.
Since there was a possibility of dust or substance attached to the flow rate adjustment valves, flushing was done on these valves on August 31.
(The required amounts of water injection for each unit were changed as follows on September 1. Unit 1: 3.8m³/h, Unit 2: 5.4m³/h, Unit 2: 5.4 m³/h)
On September 2, the opening amounts of the flow rate adjustment valves were increased to prevent substances from being attached on them as a part of investigating the cause of the flow rate decrease. The injection water amounts are continuously monitored and adjusted as necessary.

From 11:55 AM to 1:00 PM on September 4, the spool installed on the inlet side of the regular reactor injection water pump on the hill (C) on stand-by was removed for inside inspection. From 12:00 PM to 12:50 PM, investigation on the substances attached on the strainers installed at the entrance of the refrigerators used for buffer tank water cooling (2 out of 6 refrigerators). Though no substance was found inside the inlet pipe of the regular reactor injection water pump on the hill (C), some (brown and white) were found on the strainers installed at the entrance of refrigerators for buffer tank water cooling. On September 5, a camera was inserted into the buffer tank from the man hole above the buffer tank and white suspended materials were found in the tank as a result. On September 6, the substances attached on the filter used for buffer tank water sampling were analyzed, and it was found that the metal composition of the substances was mostly iron, which is of no risk. From around 9:32 AM on September 8, purification of the buffer tank water (to eliminate the suspended materials in it) was started using an underwater pump. At 1:40 PM on the same day, the purification was completed.
At 9:00 AM on September 9, purification of the buffer tank water (to eliminate the suspended materials in it) was started using an underwater pump. At 1:30 PM on the same day, the purification was completed.
At 9:00 AM on September 10, purification of the buffer tank water (to eliminate the suspended materials in it) was started using an underwater pump. At 1:00 PM on the same day, the purification was completed.

Since no significant flow rate decrease was found after the previous report (as of 3:00 PM on September 9), the water injection amounts have not been adjusted.

We will continue to investigate on the cause of this matter and monitor the water injection amounts. No significant change has been found with the bottom of RPV of each unit, other plant parameters and the monitoring post data.

- At around 3:03 PM on September 9, a TEPCO employee found that a strange sound was coming out from the duct of Unit 2 PCV gas control system installed on the first floor of Unit 2 Turbine Building. As a small hole was found on the duct upon site investigation, the hole was covered up with tape as an emergency repair. As a result, the sound stopped at 3:28 PM. No change was found with the plant parameters and monitoring post data. The PCV gas control system is continuing its operation.

- At 2:35 PM on August 27, as the salinity concentrations of Unit 4 Reactor Well and the Spent Fuel Pool had decreased, the desalination system (mobile RO) was stopped. At 11:10 AM on September 10, the ion exchanger started operating in order to further decrease the salinity concentrations.

[Fukushima Daini Nuclear Power Station]
・Unit 1 to 4: Shutdown due to the earthquake.

- On September 10, Unit 4 reactor was opened with its concrete hatch* removed. The PCV lid, the RPV lid, the steam dryer and the steam-water separator will be removed in order.
* Concrete hatch: Approx. 2m-thick concrete lid installed on top of the PCV

Appendix: Past Progress (As of 3:00 pm, on September 10, 2012) (PDF 640KB)
Appendix: 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.