Status of TEPCO's Nuclear Power Stations after the Tohoku-Chihou-Taiheiyou-Oki Earthquake (Daily Report as of 3:00 PM on August 2)

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 August 1, approx. 72m³ of water was transferred to a temporary tank.

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 August 1, approx. 60m³ of filtered water was injected.

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 30, approx. 70m³ of water was transferred to a temporary tank. On July 31, approx. 60m³ of filtered water was injected.

On August 1, 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 August 1, 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 31).

-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.

Radiation dose rate distribution measurement was conducted on the boring core of the groundwater observation hole No.5-1 (the whole boring core, which was sampled between the ground surface and 16 meter-depth level, was divided into 160 segments each corresponding to 10 cm along the depth). As a result, the highest dose rate was found in a core part sampled at depths of 1.5-2.0m from the ground surface. We consider that the peaks in core parts sampled at depths of 0.5-1m, at depths of 2.5-3.0m, and at depths of 3.5-4.0m from the ground surface were affected as those core parts were placed next to the core part sampled at depths of 1.5-2.0m that showed the highest dose rate. Therefore, we will conduct the measurement again with the core segments separated from each other. A part of the core that corresponds to depths of 2.7-5.9m from the ground surface had been solidified in a concrete-like state as a result of the foundation improvement, and there was found no trace of groundwater passing through this part.
On August 1, we conducted the measurement again while eliminating the influences of neighboring core segments by separating the core segments from each other. As a result, the peak was found only in the core part sampled at depths of 1.5-2.0m from the ground surface (OP 2.5-2.0m), and no significant values were found in the core at depths of 2.7m (OP 1.3m) and below.
We will conduct the same measurement on other groundwater observation holes to find out underground radiation dose rate distributions.

The tritium density in water sampled on July 31 in the newly installed groundwater observation hole No.1-5 (west of the groundwater observation hole No.1-3) was measured.
<Groundwater observation hole No.1-5>
- Sampling on July 31:Tritium 28,000Bq/L

The γ nuclide and all-β densities in water sampled on August 1 in the groundwater observation holes No.1, No.1-2, No.1-3, No.1-4, No.2, No.3, and No.3-1 were measured. The measured all-β density in the groundwater observation hole No.3-1 was 180Bq/L this time, up from the value of the previous sampling (on July 25), which was below the detection limit value (18Bq/L). With regards to the other measured densities, no significant change was found compared to the previous densities.

-At 11:40 AM on August 1, accumulated water transfer from the Unit 1 Turbine Building basement to Unit 1 Waste Treatment Building was started. At 4:30 PM on the same day, the transfer was stopped. At 9:38 AM on August 2, the transfer was started.

-At 2:00 PM on July 31, accumulated water transfer to the Central Radioactive Waste Treatment Facility (Process Main Building) was started. At 9:50 AM on August 2, the transfer was stopped. At 10:28 AM on the same day, accumulated water transfer from the Unit 3 Turbine Building basement to the Central Radioactive Waste Treatment Facility (Miscellaneous Solid Waste Volume Reduction Treatment Building [High Temperature Incinerator Building]) was started.

* Revised past progress

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