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 the regular plant parameter data check at 11:00 AM on November 26, a TEPCO employee found that Unit 3 reactor injection water amount had increased from 5.8m³/h (as of 10:00 AM on the same day) to 7.0m³/h (as of 11:00 AM). The technical specification for the nuclear reactor facility^*1 stipulates that an increase amount of reactor injection water from the regular use reactor injection system must be 1.0m³/h or less during any given 24 hours as an "operational requirement"^*2. Since the increase of Unit 3 reactor injection water exceeded 1.0m³/h, the shift supervisor on duty judged that the condition did not fulfill the "operational requirement" stipulated by the technical specification for the nuclear reactor facility at 11:00 AM on the same day. As the "required measure to be taken" for this incident is to start implementing measures to reduce the increase amount of reactor injection water down to the allowed range, the reactor injection water amounts at Unit 3 were adjusted as follows at 11:10 AM. Feed water system: Decreased from approx. 4.0m³/h to approx. 2.0m³/h, Reactor core spray system: Increased from approx. 3.0m³/h to approx. 4.0m³/h. Unit 3 PCV gas control system indicates no change in xenon 135 density which is below the detection limit (3.4×10^-1 [Bq/cm³]) and subcritical. There has been no significant change in the monitoring post data and no leakage around the injection line between the regular use reactor injection system and the building entrance. The reactor injection water amounts at Units 1 and 2 remain stable. Upon investigation, the cause of the increase in the reactor injection water amount was identified to be a worker unintentionally touching the handle to operate the flow rate adjustment valve while removing the heat insulating material near the flow rate adjustment valve to prepare for replacing the reactor injection water flowmeter. As a result of site investigation, no abnormality was found with the reactor water injection system and there has been no significant change in the reactor injection water amount and related parameters^*3 during the period from when the amount was adjusted to 9:00 PM on November 26. Thus, at 9:35 PM on the same day, it was judged that the condition had recovered to the state which fulfills the operational requirements.

*1 Technical specification for the nuclear reactor facility
Government-approved fundamental rules for nuclear power station operators to follow in order to maintain safe operation and stable condition of nuclear power stations (including operation management, fuel management, radiation management, emergency measures and equipment/facility management based on the "Policy on the Mid-term Security"), which are stipulated by Article 37 Section 1 of the Act on the Regulations of Nuclear Source Material, Nuclear Fuel Material and Reactors.

*2 Operational requirements
In accordance with the technical specification for the nuclear reactor facility, operational requirements are stipulated to ensure safety and stability of power stations (such as the number of available equipments, temperatures and pressures). In the case that an issue arises with equipment subject to the technical specification and the operational requirements cannot be satisfied temporarily, appropriate measures must be implemented.

*3 Related parameters
- RPV bottom temperature
- PCV inside temperature
- Radioactivity density inside the RPV (Xenon 135)
- Monitoring post data (within the grounds of the power station)

- At 9:47 AM on November 21, Unit 6 spent fuel pool cooling system was stopped for repairing the strainer changeover valve of the component seawater system (the pool water temperature when the system was stopped: 18.8℃). An alternating operation between the shutdown cooling system (for cooling the reactor) and the emergency heat load operation (for cooling the spent fuel pool) of the residual heat removal system was started. At 4:00 PM on November 26, the shutdown cooling system was stopped (the reactor water temperature when it was stopped: 26.4℃) and the emergency heat load operation was started at 4:18 PM on the same day (the pool water temperature when it was started: 26.5℃).

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

- On November 27, visual inspection of the structure inside Unit 4 reactor was started for the purpose of collecting further findings on the impact of earthquake.

Appendix: Past Progress (As of 3:00 pm, on November 27, 2012) (PDF 599KB)
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.