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

-Considering that the basements of Unit 3 and 4 Turbine Buildings are connected and the accumulated water in Unit 3 Turbine Building basement can be transferred by transferring the accumulated water in Unit 4 Turbine Building basement, the transfer pipe (polyethylene pipe) has been installed between Unit 4 Turbine Building basement and the Central Radioactive Waste Treatment Facility for the purpose of improving the reliability of accumulated water transfer pipeline. Upon completion of pipe installation, we started transferring the accumulated water in Unit 4 Turbine Building basement to the Central Radioactive Waste Treatment Facility (Miscellaneous Solid Waste Volume Reduction Treatment Building [High-temperature Incinerator Building]) at 4:15 PM on August 30.

-A worker of TEPCO confirmed that the fluctuation in the amount of water injection for Unit 1 - 3 reactor at 3:00 PM on August 30 at the regular data confirmation.

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

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

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

The shift supervisor judged that the condition did not satisfy the "Operational Requirements"^*1 defined by the Technical Specification^*2 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 below. As a result of site investigation, no water leakage from the reactor injection system was found. In order to check for air intrusion into regular use reactor injection water pump (B) and (C) which were in operation when the injection amounts started decreasing, regular use reactor injection water pump (A) was started at 11:08 PM on the same day and regular use reactor injection water pump (B) was stopped at 11:10 PM. Air vent operation was done on regular use reactor injection water pump (B), and no air intrusion was found as a result. At 11:30 PM, regular use reactor injection water pump (B) was started and regular use reactor injection water pump (C) was stopped at 11:31 PM. Upon conducting air vent operation on regular use reactor injection water pump (C), no air intrusion was found.

(Water injection amounts were adjusted as follows)
At 3:21 PM on August 30
[Unit 2] Feed-water system: Increased from 1.0m³/h to 2.0m³/h, Reactor core spray system: No change (4.0m³/h) (In total, the amount was increased from 5.0m³/h to 6.0m³/h.)
[Unit 3] Feed-water system: Increased from 1.4m³/h to 2.5m³/h, Reactor core spray system: Increased from 3.7m³/h to 4.3m³/h) (In total, the amount was increased from 5.1m³/h to 6.8m³/h.)

At 4:12 PM on the same day
[Unit 1] Feed-water system: Increased from 1.7m³/h to 3.0m³/h, Reactor core spray system: No change (2.0m³/h) (In total, the amount was increased from 3.7m³/h to 5.0m³/h.)
[Unit 2] Feed-water system: Increased from 0.9m³/h to 2.0m³/h, Reactor core spray system: No change (5.0m³/h) (In total, the amount was increased from 5.9m³/h to 7.0m³/h.)
[Unit 3] Feed-water system: Increased from 2.2m³/h to 2.5m³/h, Reactor core spray system: Increased from 4.2m³/h to 4.5m³/h (In total, the amount was increased from 6.4m³/h to 7.0m³/h.)

At 6:17 PM on the same day
[Unit 1] Feed-water system: Increased from 2.1m³/h to 3.0m³/h, Reactor core spray system: No change (2.0m³/h) (In total, the amount was increased from 4.1m³/h to 5.0m³/h.)
[Unit 2] Feed-water system: Increased from 1.1m³/h to 2.1m³/h, Reactor core spray system: Increased from 4.4m³/h to 5.0m³/h (In total, the amount was increased from 5.5m³/h to 7.1m³/h.)
[Unit 3] Feed-water system: Increased from 1.9m³/h to 2.5m³/h, Reactor core spray system: Increased from 3.8m³/h to 4.5m³/h (In total, the amount was increased from 5.7m³/h to 7.0m³/h.)

At 10:30 PM on the same day
[Unit 1] Feed-water system: Increased from 2.0m³/h to 3.0m³/h, Reactor core spray system: Increased from 1.8m³/h to 2.0m³/h (In total, the amount was increased from 3.8m³/h to 5.0m³/h.)
[Unit 2] Feed-water system: Increased from 1.8m³/h to 2.0m³/h, Reactor core spray system: Increased from 4.0m³/h to 5.0m³/h (In total, the amount was increased from 5.8m³/h to 7.0m³/h.)
[Unit 3] Feed-water system: Increased from 1.6m³/h to 2.5m³/h, Reactor core spray system: Increased from 3.4m³/h to 4.2m³/h (In total, the amount was increased from 5.0m³/h to 6.7m³/h.)

At 12:09 AM on August 31
[Unit 1] Feed-water system: Increased from 2.7m³/h to 3.0m³/h, Reactor core spray system: Increased from 1.5m³/h to 2.0m³/h (In total, the amount was increased from 4.2m³/h to 5.0m³/h.)
[Unit 3] Reactor core spray system: Increased from 4.4m³/h to 4.5m³/h, Feed-water system: No change (2.5m³/h) (In total, the amount was increased from 6.9m³/h to 7.0m³/h.)

At 3:50 AM on the same day
[Unit 1] Feed-water system: Increased from 2.8m³/h to 3.0m³/h, Reactor core spray system: No change (2.0m³/h) (In total, the amount was increased from 4.8m³/h to 5.0m³/h.)
[Unit 2] Feed-water system: Increased from 1.6m³/h to 2.0m³/h, Reactor core spray system: No change (5.0m³/h) (In total, the amount was increased from 6.6m³/h to 7.0m³/h.)
[Unit 3] Feed-water system: Increased from 2.3m³/h to 2.5m³/h, Reactor core spray system: No change (4.5m³/h) (In total, the amount was increased from 6.8m³/h to 7.0m³/h.)

At 7:24 AM on the same day
[Unit 1] Feed-water system: Increased from 2.9m³/h to 3.0m³/h, Reactor core spray system: Decreased from 2.1m³/h to 2.0m³/h (In total, the amount maintained at 5.0m³/h.)
[Unit 2] Feed-water system: Increased from 1.6m³/h to 2.0m³/h, Reactor core spray system: Decreased from 5.1m³/h to 5.0m³/h (In total, the amount was increased from 6.7m³/h to 7.0m³/h.)
[Unit 3] Feed-water system: Increased from 2.3m³/h to 2.5m³/h, Reactor core spray system: Decreased from 4.6m³/h to 4.5m³/h (In total, the amount was increased from 6.9m³/h to 7.0m³/h.)

At 11:05 AM on the same day
[Unit 1] Feed-water system: Increased from 2.4m³/h to 3.0m³/h, Reactor core spray system: Increased from 1.9m³/h to 2.0m³/h (In total, the amount was increased from 4.3m³/h to 5.0m³/h.)
[Unit 3] Feed-water system: Increased from 2.3m³/h to 2.5m³/h, Reactor core spray system: Increased from 4.3m³/h to 4.5m³/h (In total, the amount was increased from 6.6m³/h to 7.0m³/h.)

At 2:47 PM on the same day
[Unit 1] Feed-water system: Increased from 2.4m³/h to 3.0m³/h, Reactor core spray system: Increased from 1.9m³/h to 2.0m³/h (In total, the amount was increased from 4.3m³/h to 5.0m³/h.)
[Unit 2] Feed-water system: Increased from 1.7m³/h to 2.0m³/h, Reactor core spray system: Increased from 4.9m³/h to 5.0m³/h (In total, the amount was increased from 6.6m³/h to 7.0m³/h.)
[Unit 3] Feed-water system: Decreased from 2.8m³/h to 2.5m³/h, Reactor core spray system: Increased from 4.1m³/h to 4.5m³/h (In total, the amount was increased from 6.9m³/h to 7.0m³/h.)

The cause of this matter will be investigated and the water injection amounts will be continuously monitored. No change has been seen with the bottom of RSV of each unit, and no significant change is found in the monitoring post data.

*1 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 an equipment subject to the technical specification and the operational requirements cannot be satisfied temporarily, appropriate measures must be implemented.

*2 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.

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

 

Appendix: Past Progress (As of 3:00 pm, on August 31, 2012) (PDF 503KB)
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.