Status of TEPCO's Nuclear Power Stations after the Tohoku-Chihou-Taiheiyou-Oki Earthquake(Daily Report as of 3:00 PM on July 12)

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

-At around 9:02 AM on July 11, the right-side filter of a full-face mask being worn by a worker, who was working on construction of the main structure of the cesium absorption tower temporary storage facility (fourth facility), was found missing from the mask. A contamination survey was conducted on the facial surface of the worker, and no contamination was found. Thereafter, the worker underwent whole body counting and was found to have no abnormality. The filter missing from the full-face mask was found in a Tyvek protective suit that the worker took off in Welfare Building. We confirmed that the filter came off when the worker took off the Tyvek suit at a changing room in Welfare Building while taking a break, and that the worker did not perform any outdoor work wearing the mask without the filter.

-At 3:12 PM on July 11, accumulated water transfer from the Unit 3 Turbine Building basement to the Central Radioactive Waste Treatment Facility (Process Main Building) was started.
-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) 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 5, approx. 40m³ of filtered 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 into the reservoir was started.
[Recent dilution operation] On July 12, approx. 40m³ of desalination-system (RO) treated water was injected.

On July 11 and 12, 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 reservoir No.1 was transferred into this underground reservoir^*.

<Sampling>
On July 11, 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 that all-β densities in the 4 observation holes (A13, A 14, A16 and A19) around the underground reservoir No.1 were lower than those of the previous analysis (from the sampling on July 10). No significant change was found with the other analysis results.

-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.

Analysis for strontium was conducted on samples taken on June 7 in the groundwater observation holes No.1-No.3. No significant change was found compared to the previous result. Further, the all-β density in the groundwater observation hole No.2 water taken on June 9 after filtering was 890,000Bq/L, which is not significantly different from the density (900,000Bq/L) in the unfiltered sample (taken on July 9).
Analysis for the γ nuclides and all-β was conducted on samples taken on July 11 in the groundwater observation holes No.1, No.1-2, No.1-4, No.2, and No.3. The all-β density in the groundwater observation hole No.3 was detected at 1,400Bq/L, which is higher than the previous density (ND (18Bq/L) in the sample taken on July 4). No significant change was found with the other densities compared to the previous results.

 

* There has been a mistranslation in the part starting with "leaked water in the drain holes". This part has been corrected from "leaked water in the drain holes at the underground reservoir No.2 was transferred into this underground reservoir" (corrected on July 16). We apologize for the mistranslation.

* Revised past progress

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