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
- As for the installation of Unit 2 RPV alternative thermometer, the RPV pressure was found to be higher than that measured during the mockup testing. At 10:33 PM on October 1, the flow rate of the nitrogen injected into Unit 2 PCV was changed from 5m3/h to 0m3/h. As the amount of nitrogen injection into the RPV has been maintained at 15m3/h while the necessary minimum flow rate is 9m3/h, there should be no impact on safety. Due to the change in nitrogen injection amount, monitoring of the hydrogen concentration in the PCV, PCV pressure, PCV ambient temperature and reactor pressure has been enhanced. As the RPV pressure has been decreasing (6kPa as of 5:00 AM on October 2), insertion of the coil guide (which functions as a guide for thermometer installation) was started at 9:39 AM on October 2. The insertion was completed at 11:57 AM on the same day.
- At 4:47 PM on October 1, Units 1-3 reactor injection water amounts were adjusted as follows since the amounts had fluctuated after a regular switching of the reactor water injection pumps.
[Unit 1] Feed water system: Increased from approx. 2.7m3/m to approx. 3.0m3/h, Reactor core spray system: Increased from approx. 1.9m3/h to approx. 2.0m3/h.
[Unit 2] Feed water system: Increased from approx. 1.7m3/m to approx. 2.0m3/h, Reactor core spray system: Maintained at approx. 5.0m3/h.
[Unit 3] Feed water system: Increased from approx. 2.4m3/m to approx. 2.5m3/h, Reactor core spray system: Maintained at approx. 4.5m3/h.
- At 10:05 AM on September 29, we started transferring the accumulated water in Unit 2 Turbine Building basement to Unit 3 Turbine Building basement. At 10:12 AM on October 2, the transfer was stopped.
- At around 9:40 AM on October 2, a worker of a cooperative company found white smoke coming out from the motor of the vacuum pump for vessel ventilation*1 at the outdoor cesium absorption tower temporary storage facility*2 in the south of the Central Environment Facility. After turning off the power of the pump, the smoke stopped coming out. At around 10:20 AM on the same day, the incident was reported to the fire department and the fire department judged that the incident was not a fire at 12:54 PM on the same day. The pump and its motor were replaced with another vacuum pump for vessel ventilation and its motor not in use. As no problem was found as a result of trial operation, full-scale operation was started at 3:50 PM on the same day. The cause of the smoke coming out will be investigated. There has been no impact found on the surrounding equipments or change in the monitoring post data due to this incident.
*1 Vacuum pump for vessel ventilation: Pump to suck in the hydrogen generated by water radiolysis in the vessel through the vent valve. Since the amount of hydrogen generated in the vessel is quite small, there is no immediate safety issue even if the pump is stopped.
*2 Outdoor cesium absorption tower temporary storage facility: Facility to store the vessels used in the cesium absorption apparatus. The facility has no impact on reactor water injection and accumulated water treatment.
- On September 13, Unit 5 residual heat removal system seawater pump A was stopped for inspection to investigate the cause of its performance degradation, and the residual heat removal system was switched from A to B accordingly. As the inspection was completed on October 2, the residual heat removal system seawater pump A was started at 10:33 AM on the same day. At 11:57 AM, the residual heat removal system B was stopped and the residual heat removal system A was started at 12:26 PM on the same day (the reactor water temperature when the system B was stopped: 29.4℃, the reactor water temperature when the system A was started: 30.0℃). As a result of inspection, pieces of vinyl and plastic were found in the suction part of the residual heat removal system seawater pump A which have been removed. These pieces of vinyl and plastic are considered to be the cause of performance degradation of the residual heat removal system seawater pump A.
[Fukushima Daini Nuclear Power Station]
・Unit 1 to 4: Shutdown due to the earthquake.
- At 12:10 PM on October 1, we started moving the fuel in Unit 4 reactor to the spent fuel pool.
* An update on adjustment of reactor injection amounts performed at 4:47 PM on October 1 has been added since it was missing in the daily report announced on October 2, 2012. We apologize for the mistake. (Correction made on January 18, 2013)
Past Progress (As of 4:00 pm, on October 2, 2012) (PDF 544KB)
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.