Status of TEPCO's Nuclear Power Stations after the Tohoku-Chihou-Taiheiyou-Oki Earthquake (Daily Report as of 3:00 PM, April 7)

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 10:29 AM on April 5, we started transferring the accumulated water in Unit 2 Turbine Building basement to the Central Radioactive Waste Treatment Facility (Miscellaneous Solid Waste Volume Reduction Treatment Building [High Temperature Incinerator Building]). At 5:53 PM on April 6, the transfer was stopped.

-At 6:43 PM on April 6, we started transferring the accumulated water in Unit 2 Turbine Building basement to Unit 3 Turbine Building basement.

-As for the underground reservoir No.2 installed within the power station site on April 3, 10¹Bq/cm³ level of radiation was detected as a result of analyzing the water accumulated between the sheet on the outside (bentonite sheet) and the ground (the underground reservoir is made of three layers of impermeable sheets). On April 5, radiation was detected in the water between the sheet on the outside (bentonite sheet) and the sheet on the inside (double-layered permeable sheet) as a result of analysis. The radioactivity density of all β detected was approx. 5.9×10³Bq/cm³. Considering that there is no drain ditch in the surrounding area, it is considered that there is no possibility of the leaked water flowing into the sea. At 5:43 AM on April 6, we started transferring the water stored in the underground reservoir No.2 to the underground reservoir No.1 utilizing a permanent pump. Considering that the amount of leaked water is approx. 120m3, all γ radioactivity density is approx. 1.5×10⁰Bq/cm³ and all β radioactivity density is approx. 5.9×10³Bq/cm³, the γray radiation dose leaked is estimated to be approx. 1.8×10⁸Bq and the β radiation dose leaked is estimated to be approx. 7.1×10¹¹Bq. Details are currently being investigated.
As three temporary pumps were added and no problem was found with the temporary water transfer line, we started transferring the water from the underground reservoir No.2 to No.1 at 9:38 AM on the same day. In order to add another temporary pump, the pumps other than the permanent pump (3 temporary pumps) were temporarily suspended at 12:27 PM on the same day. Since no problem was found with the temporary pipeline of the newly added temporary pump, the water transfer from the underground reservoir No.2 to No.1 was started at 12:52 PM. The three temporary pumps suspended were restarted at 12:57 PM for water transfer from the underground reservoir No.2 to No.1. In order to use the permanent facility for water transfer to the underground reservoir No.6, the water transfer to the underground reservoir No.1 was suspended at 3:33 PM on the same day. At 4:10 PM, water transfer from the underground reservoir No.2 to No.6 was started. Water transfer from the underground reservoir No.2 to No.1 utilizing temporary pumps is continued. On April 6, sampling was performed in the underground reservoirs. The results are as follows.

[Underground reservoir No.1: Water in the drain hole] (Sample collected at 9:15 AM on April 6)
[Analysis results]
- All β: 6.9×10^^-2Bq/cm³ (Detection limit: 3.3×10^^-2Bq/cm³)
- Chloride concentration: 13ppm

[Underground reservoir No.2: Water in the leakage detection hole in the northeast side] (Sample collected at 1:56 PM on April 6)
[Analysis results]
- All β: 6.9×10^^-3Bq/cm³ (Detection limit: 3.1×10^^-0Bq/cm³)
- Chloride concentration: 500ppm

[Underground reservoir No.2: Water in the leakage detection hole in the southwest side] (At 2:17 PM on April 6)
*Sampling was not performed since the amount of sample necessary for analysis could not be collected.

[Underground reservoir No.2: Water in the drain hole in the southwest side] (Sample collected at 9:20 AM on April 6)
[Analysis results]
- All β: 4.8×10^^-2Bq/cm³ (Detection limit: 3.3×10^^-2Bq/cm³)
- Chloride concentration: 8ppm

[Underground reservoir No.2: Water in the drain hole in the northeast side] (Sample collected at 9:25 AM on April 6)
[Analysis results]
- All β: 4.3×10^^-1Bq/cm³ (Detection limit: 3.3×10^^-2Bq/cm³)
- Chloride concentration: 14ppm

[Underground reservoir No.3: Water in the drain hole] (Sample collected at 9:30 AM on April 6)
[Analysis results]
- All β: 1.1×10^^-1Bq/cm³ (Detection limit: 3.3×10^^-2Bq/cm³)
- Chloride concentration: 10ppm

[Underground reservoir No.4: Water in the drain hole] (Sample collected at 9:45 AM on April 6)
[Analysis results]
- All β: Below the detection limit (Detection limit: 3.3×10^^-2Bq/cm³)
- Chloride concentration: 9ppm

On the same day, sampling was performed on the water in the leakage detection holes of the underground reservoir No.3 located in the east of No.2. The results are as follows.

[Underground reservoir No.3: Water in the leakage detection hole in the northeast side] (Sample collected at 9:50 PM on April 6)
[Analysis results]
- All β: 1.8×10^^-1Bq/cm³ (Detection limit: 3.1×10^^-2Bq/cm³)
- Chloride concentration: 1ppm or less

[Underground reservoir No.3: Water in the leakage detection hole in the southwest side] (Sample collected at 10:20 PM on April 6)
[Analysis results]
- All β: 1.8×10^³Bq/cm³ (Detection limit: 3.1×10^⁰Bq/cm³)
- Chloride concentration: 350ppm

While enhancing monitoring of the water level of the underground reservoir No.3, on April 7, sampling was performed on the water in the drain hole (in the southwest side) and the leakage detection hole (in the southwest side) of the underground reservoir No.3 for the purpose of investigating the leakage location. The results are as follows.

[Underground reservoir No.3: Water in the drain hole in the southwest side] (Sample collected at 3:15 AM on April 7)
[Analysis results]
- All β: 4.5×10^^-2Bq/cm³ (Detection limit: 3.2×10^^-2Bq/cm³)
- Chloride concentration: 1ppm

[Underground reservoir No.3: Water in the leakage detection hole in the southwest side] (Sample collected at 3:45 AM on April 7)
[Analysis results]
- All β: 2.2×10^³Bq/cm³ (Detection limit: 3.2×10^⁰Bq/cm³)
- Chloride concentration: 380ppm

Considering that all β nuclides were detected in the water in the leakage detection hole and the drain hole of the underground reservoir No.3 as a result of sampling, it is assumed that there has been a small amount of leakage from the impermeable sheet on the outside (bentonite sheet) of the reservoir to the outside though no water level decrease has been found at the underground reservoir No.3. On the same day, sampling was performed on the water in the drain hole (in the northeast side) and the leakage detection hole (southwest side: by vacuuming method^*) of the underground reservoir No.3. The results are as follows.

[Underground reservoir No.3: Water in the drain hole in the northeast side] (Sample collected at 3:20 AM on April 7)
[Analysis results]
- All β: Below the detection limit (Detection limit: 3.2×10^^-2Bq/cm³)
- Chloride concentration: 10ppm

[Underground reservoir No.3: Water in the leakage detection hole in the southwest side] (Sample collected at 4:15 AM on April 7)
[Analysis results]
- All β: 2.1×10^³Bq/cm³ (Detection limit: 3.2×10^⁰Bq/cm³)
- Chloride concentration: 380ppm

As for the water in the leakage detection hole (in the southwest side) of the underground reservoir No.3, the chloride concentration and all β nuclides that are equivalent to those of the sample collected at 3:45 AM on the same day were detected.

*Vacuuming method: A method to collect samples by utilizing a suction machine and a hose.

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

* Revised past progress

The aforementioned attachments are only available in Japanese.
We apologize for any inconvenience this may cause.