The following is the known status as of Monday morning of each of the six reactors at the Fukushima Daiichi nuclear power plant and the four reactors at the Fukushima Daini plant, both in Fukushima Prefecture, which were crippled by the magnitude 9.0 earthquake and ensuing tsunami on March 11.
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 6:55 PM on November 29, Units 2-3 reactor injection water amounts were adjusted as follows since the amounts had fluctuated.
[Unit 2] Feed water system: Increased from approx. 1.8m3/h to approx. 1.9m3/h, Reactor core spray system: Decreased from approx. 4.1m3/h to approx. 3.9m3/h.
[Unit 3] Feed water system: Increased from approx. 1.8m3/h to approx. 2.1m3/h, Reactor core spray system: Increased from approx. 3.6m3/h to approx. 4.0m3/h.
-At 1:54 PM on November 25, Unit 1 spent fuel pool alternative cooling system was stopped in prior to the common power supply modification which suspends the power supply to the system from November 27 to 28 (the pool water temperature when the system was stopped: 16.0°C). Though cooling was originally planned to be restarted on November 28, it has been postponed to November 29 due to the schedule change of the power supply suspension. Upon checking the spent fuel pool alternative cooling system in prior to restart after the power supply to the system was recovered on November 29, an alarm indicating an abnormality with the heat exchanger secondary system radiation monitor had gone off and the radiation monitor reading had been downscaled. For this reason, the radiation monitor will be inspected on November 30 before cooling is restarted. Unit 1 spent fuel pool water temperature increase rate is approx. 0.088°C/h and the pool water temperature as of 12:00 AM on November 30 was approx. 25.3°C. There is no problem with the spent fuel pool water temperature control considering the sufficient margin to the maximum allowed temperature (65°C).
-On October 4, Unit 3 spent fuel pool desalination system (mobile RO) was stopped due to an alarm indicating the buffer tank water level being too high. Also on October 24, hydrochloric acid leaked from 25% hydrochloric acid tank when the system was under suspension. As the increase in the buffer tank water level was assumed to have been caused by some of the water gauges not working properly due to scale* stuck in them, acid cleaning was done of the water gauges. The effectiveness of the acid cleaning (scale removal) was checked by putting the system in hydrochloric acid injection operation. Since the cause of the hydrochloric acid leakage was identified to be the joint part not resistant to 25% hydrochloric acid being damaged (dissolved), the part has been replaced with a hydrochloric acid resistant material. As preparation for trial operation was completed, the system was restarted. At 10:50 AM on November 30, the full-scale operation of the system was started since no problem had been found with its operation.
* Calcium carbonate which originates from the calcium dissolved in the spent fuel pool water
[Fukushima Daini Nuclear Power Station]
·Unit 1 to 4: Shutdown due to the earthquake.