Status of TEPCO's Nuclear Power Stations after the Tohoku-Chihou-Taiheiyou-Oki Earthquake (Daily Report as of 3:00 PM on July 28)

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 27, approx. 60m³ of filtered water was injected.

<Sampling>
On July 27, 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 26).

-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.

-We measured chlorine concentration and γ nuclide, all-β and tritium 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 were high compared to those in the sample taken on July 17 from the nearby water intake power cable trench (B2). 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 (in terms of cesium-134 and cesium-137 densities).

<Measured densities in water of Unit 2 water intake power cable trench (B1-1: seawater piping foundation part) (sampled on July 26)>
Chlorine 8,000ppm
Cesium-134 750,000,000Bq/L (750,000Bq/cm³)
Cesium-137 1,600,000,000Bq/L (1,600,000Bq/cm³)
All-β 750,000,000Bq/L (750,000Bq/cm³)
Tritium 8,700,000Bq/L (8,700Bq/cm³)

(Reference)
<Measured densities in water of Unit 2 water intake power cable trench (B2) (sampled on July 17)>
Chlorine 70ppm
Cesium-134 12,000,000Bq/L (12,000Bq/cm³)
Cesium-137 24,000,000Bq/L (24,000Bq/cm³)
All-β 23,000,000Bq/L (23,000Bq/cm³)
Tritium 120,000Bq/L (120Bq/cm³)

<Measured densities in water leaked into the Unit 2 water intake screen room in April 2011>
Cesium-134 1,800,000,000Bq/L (1,800,000Bq/cm³)
Cesium-137 1,800,000,000Bq/L (1,800,000Bq/cm³)

* Revised past progress

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