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.
At 10:42 AM on September 11, the set value for the alarm indicating a decrease of Unit 1-3 reactor injection water amounts has been set to the current decay heat equivalent water injection amount. The set value will be changed as necessary.

Since no significant flow rate decrease was found after the previous report (as of 3:00 PM on September 10), 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 10:00 AM on September 11, we started transferring the accumulated water in Unit 6 Turbine Building basement to the temporary tank. At 3:00 PM on the same day, the transfer was stopped.

- At 10:22 AM on September 11, we started transferring the accumulated water in Unit 3 Turbine Building basement to the Central Radioactive Waste Treatment Facility (Miscellaneous Solid Waste Volume Reduction Treatment Building [High Temperature Incinerator Building]).

- At around 12:19 PM on June 19, a TEPCO employee found damages (at 8 locations) on the PCV gas control system duct near the feed-water heating room entrance on the first floor of Unit 3 Turbine Building, with a strange sound coming out from the damaged areas. At around 2:40 PM, it was found that the damaged areas were maintained at negative pressure and the gas has not leaked out of the duct. No change was found with the PCV pressure, the hydrogen concentration inside the PCV and the exhaust gas flow rate of the PCV gas control system at Unit 3. At 4:30 PM, the damaged areas were covered up with tape as an emergency repair. As the preparation for a duct replacement was completed, the PCV gas control system was stopped^* for duct replacement at 10:26 AM on September 11. At 11:30 AM on the same day, the PCV gas control system was restarted as the replacement was completed. At 1:06 PM on the same day, the measurement utilizing the noble gas monitor was restarted. No change was found with monitoring parameters while the system was stopped.
* The facility management policy in accordance with Article 12 of the technical specification for the nuclear reactor facility "Policy on the Mid-term Security" stipulates "operational requirements" and "required measures in the case that the operational requirements are not fulfilled". When the operational requirements are not fulfilled, the required measures must be implemented. In this case, Unit 3 PCV gas control system was intentionally stopped (transition out of the scope of operational requirements) for maintenance (From 10:26 AM to 1:06 PM on September 11).

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

Appendix: Past Progress (As of 3:00 pm, on September 11, 2012) (PDF 525KB)
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.