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Top > Releases ・ Announcements > Press Releases > 2013 > Status of TEPCO's Nuclear Power Stations after the Tohoku-Chihou-Taiheiyou-Oki Earthquake(Daily Report as of 4:00 PM, January 25)

Press Releases 2013

Press Release (Jan 25,2013)Status of TEPCO's Nuclear Power Stations after the Tohoku-Chihou-Taiheiyou-Oki Earthquake(Daily Report as of 4:00 PM, January 25)

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

- From 1:54 PM to 2:22 PM on January 24, Unit 1 spent fuel pool alternative cooling system was suspended while feeding water to the skimmer surge tank of Unit 1 spent fuel pool by a fire pump car. The spent fuel pool water temperature when the cooling system was restarted was 10.0℃, which was the same as that of when the cooling was suspended. (Though usually water is fed into Unit 1 spent fuel pool skimmer surge tank via the filtrate water pipe, a fire pump car was used instead since the main valve of the filtrate water pipe is closed due to leakage from the valve installed on the filtrate water pipe header found on January 19.) While feeding water into the skimmer surge tank by a fire pump car, water (filtrate water) leakage was found at the flange of the water feeding pipe installed in the large carry-in entrance at Unit 1 Reactor Building. The amount of leaked water is approx.2L (Affected area: Approx. 2mx1m with a small depth). The leakage stopped after water feeding into the skimmer surge tank was stopped. From 2:42 PM to 3:05 PM on January 25, Unit 1 spent fuel pool alternative cooling system was suspended in order to feed water into the skimmer surge tank by a fire pump car after the leakage area was repaired. The spent fuel pool water temperature when the cooling was restarted was 10.5℃ (the same as when the cooling was suspended). No problem was found with the leakage location.

- At around 1:15 PM on January 19, a TEPCO employee found filtrate water leaking in the form of a mist from the filtrate water header valve used for feeding water to the spent fuel pool which is installed in the former Water Treatment Building. The area affected by leakage is approx. 1mx1m when the leakage was first found. The leaked water is kept in the building and has not flowed to the outside. After closing the valve located in the upstream side of the filtrate water pipe, the leakage amount was reduced to 2 drops per second. As a result of inspection, a crack was found on the filtrate water header valve where the leakage was found. As a result of investigation performed afterwards, it was found that though the valve of concern is installed inside the building, the installation condition is the same as those installed outside considering that the outer walls of the building were damaged due to the earthquake and no insulation material was installed on or near the valve. Under such installation conditions, the water remaining in the pipe froze and the pipe got expanded causing the valve to be damaged. As the valve and the pipe on which the valve is installed are not planned to be used, the valve has been removed and a closure panel has been installed on the flange in the upstream side of the pipe. Insulation material was also installed on the pipe to prevent freezing. After implementing these measures, water dripping was stopped. We will check the valve for leakage and install insulation material on the valves installed in the building. The incident has no impact on feeding water to the spent fuel pool.

- On January 24, after replacing the gasket of the flange on the pipe which feeds water into the chemical tank of the decontamination equipment (flange located on the tank side of the reducer), a TEPCO employee found filtrate water leaking from the reducer at around 3:10 PM while checking for leakage using fire hydrant water (filtrate water). The leakage stopped after closing the main valve of the fire hydrant. The amount of leakage was approx. 20L (affected area: approx. 3mx3mx2mm in depth) and the leaked water remains in the dam of the chemical tank. Considering that a crack was found on the reducer and no insulation material was attached on it, the crack is assumed to have been caused by freezing. The damaged reducer will be repaired with insulation material attached on it.

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

* Revised past progress

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