Status of TEPCO's Nuclear Power Stations after the Tohoku-Chihou-Taiheiyou-Oki Earthquake (Daily Report as of 3:00 PM, March 20)

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 6:57 PM on March 18, there was an incident where the power supply facilities in the Main Anti-earthquake Building momentarily stopped. Upon investigation, it was found that part of the power supply facilities at Fukushima Daiichi Nuclear Power Station have stopped due to the incident and the following facilities were suspended accordingly.
- Cesium adsorption apparatus of the water treatment facility
- Unit 1 spent fuel pool alternative cooling system^* (Secondary system)
- Unit 3 spent fuel pool alternative cooling system (Primary and secondary systems)
- Unit 4 spent fuel pool alternative cooling system (Primary and secondary systems)
- Unit 3 PCV gas control system (A system)
- Common pool cooling purification system
- Nitrogen separator (B)
* The primary system of Unit 1 spent fuel pool alternative cooling system was manually stopped at 9:10 PM for the purpose of protecting the pumps of the system.
No problem was found with the following facilities due to the incident.
- Units 1-3 reactor water injection systems
- Monitoring posts
- Units 1-3 PCV gas control systems (being monitored)
- Unit 2 spent fuel pool alternative cooling system
- Units 1-3 nitrogen injection equipment
- Nitrogen separator (A)
The later updates on the incident are provided as below.
- Nitrogen separator (B) was started at 3:00 AM on March 19 and nitrogen supply was started at 3:10 AM on the same day.
- The regular M/C in the Process Building has received power from the backup M/C in the Process Building at 9:03 AM on March 19. The common M/C4A has received power from the regular M/C in the Process Building at 10:01 AM on the same day.
- The cesium adsorption apparatus of the water treatment facility was started at 12:01 PM on March 19 and the steady flow rate was achieved at 12:17 PM on the same day. No problem has been found with its operation.
- The primary system of Unit 4 spent fuel pool alternative cooling system was started at 1:20 PM on March 19. No problem has been found with its operation.
- The primary and secondary systems of Unit 1 spent fuel pool alternative cooling system were started at 2:20 PM on March 19. No problem has been found with its operation.
- 4:13 PM on March 19, Unit 4 spent fuel pool alternative cooling system secondary system was restarted by utilizing a temporary power supply (diesel generator). No problem has been found with its operation.
- At 5:00 PM on March 19, Unit 3 PCV gas control system A system has been recovered.
- At 6:48 PM on March 19, Unit 4 spent fuel pool alternative cooling system secondary system was temporarily suspended in order to switch to the permanent power supply.
- At 10:26 PM on March 19, Unit 4 spent fuel pool alternative cooling system secondary system was restarted utilizing the permanent power supply. No problem has been found with its operation.
- At 10:43 PM on March 19, the primary and secondary systems of Unit 3 spent fuel pool alternative cooling system have been restarted. No problem has been found with their operation.
- At 12:12 AM on March 20, the common pool cooling purification system was restarted. No problem has been found with its operation.
At around 12:36 PM on March 20, during the investigation of the power supply facilities failure, a TEPCO employee found soot on the terminals and the wall surfaces inside Units 3-4 temporary M/C (A). The incident was reported to Futaba Fire Department at 12:45 PM. Upon investigation, the fire department judged that the incident was not a fire at 1:57 PM.

-At 10:27 AM on March 15, we started transferring the accumulated water in Unit 3 Turbine Building basement to the Central Radioactive Waste Treatment Facility (Process Main Building). At 10:34 AM on March 19, the transfer was stopped since the accumulated water level monitoring has been disabled after the power supply of the Main Anti-earthquake Building being momentarily stopped at around 6:57 PM on March 18. At 9:56 AM on March 20, the transfer has been restarted as the accumulated water level monitoring was recovered.

-At 10:20 AM on March 20, systems A and B of Unit 1 PCV gas control system were suspended^* in accordance with Article 136 Section 1 of the technical specification in order to relocate the power supply related facilities and modify the control system (transition out of the scope of the operational requirements for maintenance work). After the work was completed, systems A and B were started and the application of Article 136 Section 1 was lifted at 11:50 AM on the same day as no problem was found with their operation. No abnormality was found with the monitoring parameters during the system suspension.
*The facility management policy based on Chapter 12 of the technical specification for the nuclear reactor facility "Policy on the Mid-term Security" stipulates "operational requirements" and "necessary measures to be implemented in the case that the operational requirements are not fulfilled" (When the operational requirements are not fulfilled, the required measures must be implemented).

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

*Regarding Unit 1 PCV gas control system being suspended in order to relocate the power supply related facilities and modify the control system from 10:20 AM to 11:50 on March 20, it said in the daily report previously released that "system B was suspended and started as the work had completed", however, it has been corrected to "systems A and B were suspended and started as the work had completed". We apologize for the mistake. (Correction made on March 21, 2013)

*In the daily report previously announced, it said "at 10:20 AM on March 20, systems A and B of Unit 1 PCV gas control system were suspended in order to relocate the power supply related facilities and modify the control system. At 11:50 AM on the same day, systems A and B were started as the work had completed", however, the statement has been corrected to "- At 10:20 AM on March 20, systems A and B of Unit 1 PCV gas control system were suspended^* in accordance with Article 136 Section 1 of the technical specification in order to relocate the power supply related facilities and modify the control system (transition out of the scope of the operational requirements for maintenance work). After the work was completed, systems A and B were started and the application of Article 136 Section 1 was lifted at 11:50 AM on the same day as no problem was found with their operation". We apologize for the mistake. (Correction made on March 23, 2013)

* Revised past progress

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