Status of TEPCO's Nuclear Power Stations after the Tohoku-Chihou-Taiheiyou-Oki Earthquake (Daily Report as of 3:00 PM on July 27)

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 Fukushima Daiichi Nuclear Power Station.

* 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

- Contaminated water transfer from the underground reservoirs was all completed as of July 1. However, we are continuing to take measures to prevent the expansion of contaminated water, and to conduct sampling activities.

<Measures to prevent the expansion of contaminated water>
On June 19, since the decrease of all-β radioactivity density in the leakage detection hole (northeast) at the underground reservoirs No.1 has been slow, an operation to dilute the underground reservoir No.1 by transferring desalination-system (RO) treated water (the all-β radioactivity density: approx. 1×10¹Bq/cm³) or filtered water into the reservoir was started (the all-β radioactivity density of residual water in the underground reservoir No.1: 6.6×10⁴Bq/cm³).
[Recent dilution operation] On July 25, approx. 60m³ of desalination-system (RO) treated water was injected.

On June 27, since the decrease of all-β radioactivity density in the leakage detection hole (northeast) at the underground reservoirs No.2 has been slow, an operation to dilute the underground reservoir No.2 by transferring filtered water or desalination-system (RO) treated water (the all-β radioactivity density: approx. 1×10¹Bq/cm³) into the reservoir was started.
[Recent dilution operation] On July 25, approx. 70m³ of water was transferred to a temporary tank.

On July 24, since the decrease of all-β radioactivity density in the leakage detection hole (southwest) at the underground reservoirs No.3 has been slow, an operation to dilute the underground reservoir No.3 by transferring filtered water or desalination-system (RO) treated water (the all-β radioactivity density: approx. 1×10¹Bq/cm³) into the reservoir was started.
[Recent dilution operation] On July 24, approx. 40m³ of desalination treated water was injected. On July 26, approx. 40m³ of water was transferred to a temporary tank. On July 27, approx. 60m³ of filtered water was injected.

On July 26 and 27, leaked water in the leakage detection holes at the underground reservoirs No.1-No.3 was transferred to the temporary aboveground tank, and leaked water in the drain holes at the underground reservoirs No.1 and No.2 was transferred into these underground reservoirs.

<Sampling>
On July 26, sampling was performed in the drain holes of the underground reservoirs No.1-No.7 (14 locations), the leakage detection holes of the underground reservoirs No.1-No.4 and No.6 (sample could not be collected at 2 out of 10 locations), and the observation holes of the underground reservoirs (22 locations). The analysis results showed no significant change compared to the results from sampling previously performed (on July 25).

- We installed observation holes east of the Unit 1-4 Turbine Buildings, and have been conducting sampling and analysis of groundwater from the observation holes. On June 19, we announced that tritium and strontium were detected at high densities in the observation hole located between Units 1 and 2. Therefore, we have been conducting intensified monitoring.

- The tritium density in water sampled on July 25 in the newly dug-up groundwater observation hole No.2-1 (east of the groundwater observation hole No.2) and the densities listed below were measured. The tritium density in water sampled in the groundwater observation hole No.2-1 was low compared to that in the nearby located groundwater observation hole No.2. With regards to the other densities, no significant change was found compared to the previous densities.
<Measurement in locations other than the groundwater observation hole No.2-1>
·Tritium in the groundwater observation holes No.1, No.1-2, No.1-3, No.1-4, No.2 and No.3 (samples taken on July 22)
·γ nuclides and all-β in the groundwater observation holes No.1, No.1-2, No.1-3, No.1-4, No.2, No.3 and No.3-1 (samples taken on July 25)
·Tritium in seawater inside the port (samples taken on July 22 and 23)
·γ nuclides and all-β in seawater in the Unit 1-4 water intake north side and seawater between the water intakes of Units 1 and 2 (near the surface and near the bottom) (samples taken on July 25), which are included in seawater inside the port
·γ nuclides in the groundwater observation hole No.1-2 after filtering (a sample taken on July 25)

- We measured chlorine concentration and γ nuclide and all-β densities in water sampled on July 26 from the Unit 2 water intake power cable trench (seawater piping foundation part) where a new observation hole (B1-1) was installed for the survey conducted for purposes such as identification of the contamination source of high-density contaminated water inside the sea-side trench. These measurement results on the Unit 2 seawater piping foundation part cannot be compared directly since the location is a new observation point. However, the values (chlorine concentration of 8,000ppm, cesium-134 density of 750,000,000Bq/L (750,000Bq/cm³), cesium-137 density of 1,600,000,000Bq/L (1,600,000Bq/cm³), and all-β density of 750,000,000Bq/L (750,000Bq/cm³)) were high compared to those in the sample taken on July 17 from the nearby water intake power cable trench (a sample taken on July 17, which showed chlorine concentration of 70ppm, cesium-134 density of 12,000,000Bq/L (12,000Bq/cm³), cesium-137 density of 24,000,000Bq/L (24,000Bq/cm³), and all-β density of 23,000,000Bq/L (23,000Bq/cm³)). These densities found this time are at the same levels as those found in water leaked into the Unit 2 water intake screen room in April 2011 (quality of water leaked into the vicinity of the Unit 2 water intake screen in April 2011 was such that cesium-134 and cesium-137 densities were both 1,800,000,000Bq/L (1,800,000Bq/cm³)).

End

* Revised past progress

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