Status of TEPCO's Nuclear Power Stations after the Tohoku-Chihou-Taiheiyou-Oki Earthquake (Daily Report as of 3:00 PM on August 13)

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>
· Since the decreases of all-β radioactivity densities in the leakage detection holes (at the northeast side of the underground reservoir No.1, the northeast side of the underground reservoir No.2, and the southwest side of the underground reservoir No.3) have been slow, operations to dilute the underground reservoirs No.1-No.3 by transferring filtered water or desalination-system (RO) treated water (the all-β radioactivity density: approx. 1×10¹Bq/cm³) into these reservoirs have been conducted as appropriate.
[Recent dilution operations]
Underground reservoir No.1 (since June 19): On August 3, approx. 60m³ of filtered water was injected.
Underground reservoir No.2 (since June 27): On August 1, approx. 60m³ of filtered water was injected.
Underground reservoir No.3 (since July 24): On August 11, approx. 51m³ of water in the drain hole (northeast) of this underground reservoir was injected.

· On August 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 reservoirs No.1 and No.2 was transferred into these underground reservoirs.

<Sampling>
On August 12, 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), the observation holes of the underground reservoirs (22 locations), and the observation holes on the sea side (5)-(8). As a result of the analysis, no significant change was found compared to the analysis results from the sampling performed previously (on August 5 in the observation holes on the sea side (5)-(8) and on August 11 in the other locations).

-On August 10, at the underground reservoir No.3, uplift of about 40-cm centering on the center of the levee crown was found. In response, the other underground reservoirs were checked, and similar uplift of about 15-cm was found at the underground reservoir No.4. We are currently considering that the uplift was caused by an increase in buoyant force due to increases of the water levels of groundwater around the underground reservoirs. Since no significant change has been found in the analysis results on water in the underground reservoir drain holes and leakage detection holes, this uplift did not cause contaminated water to leak. We will consider measures against such uplift, and closely monitor analysis results on water in the underground reservoir drain holes and leakage detection holes.

-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.

· At 2:10 PM on August 9, we started pumping up groundwater from the water collection pit (south) installed east of Units 1 and 2 Turbine Buildings and transferring the pumped-up groundwater to the Unit 2 vertical shaft C.

-At around 12:33 PM on August 12, an alarm indicating a high radioactivity density went off at the continuous dust monitor installed in front of the Main Anti-earthquake Building. Due to this, at 12:48 PM on the same day, an instruction was given to put on masks in the areas where the wearing of full-face (or half-face) masks is not required in the power station site. Neither abnormality in the plant data (reactor injection water amount, spent fuel pool water temperature, etc.) nor significant change in the monitoring post data and in the readings of continuous dust monitors installed at other locations was found. We therefore consider that this incident has no impact on the outside of the power station. Meanwhile, we provide water mist spray in front of the Main Anti-earthquake Building to prevent heat stroke, and the contamination measurement conducted through the exit monitor at the Entrance Area Management Building found out that 10 people who had been waiting for a bus in front of the Main Anti-earthquake Building had contamination on their bodies. As their heads and faces were found contaminated (with the maximum dose being approx. 19Bq/cm²), these people were instructed to receive whole body counting. At 1:25 PM on the same day, the mist generator was stopped since we suspected that the contamination of the bodies may be attributable to contamination of mist generated by the mist generator. Further, since water (for lavatories, etc.) used in the Main Anti-earthquake Building and Units 5 and 6 comes from the same water source as water supplied to the mist generator, use of water for lavatories, etc, was prohibited at 1:16 PM on the same day. At 1:40 PM on the same day, the main valve of water supplied to the mist generator and water used in the Main Anti-earthquake Building and Units 5 and 6 was shut off.
Dust measurement conducted in front of the Main Anti-earthquake Building (with dust sampled from 1:05 to 1:25 PM) resulted in 1.4×10^-5Bq/cm³ (all-β density). Later, dust measurement conducted again in front of the Main Anti-earthquake Building (with dust sampled from 2:10 to 2:30 PM) resulted in 1.2×10^-5Bq/cm³ (all-β density). In addition, the continuous dust monitor installed in front of the Main Anti-earthquake Building indicated the value of 1.1×10^-5Bq/cm³, which is sufficiently below the full-face mask wearing standard^*1 (2.0×10^-4Bq/cm³). Therefore, at 4:17 PM on the same day, the instruction to put on masks in the areas not requiring full-face (or half face) masks in the power station site was retracted. Meanwhile, we confirmed that the contamination levels of the 10 people found contaminated were below the screening level (40Bq/cm²), and they were therefore allowed to leave the Entrance Area Management Building. However, so that contamination can be reliably cleared, their bodies were wiped down. At 2:13 PM on the same day, they left the Entrance Area Management Building. After the wiping down, the maximum contamination level among the 10 people found contaminated was 6.9Bq/cm^2*. Then, they received the whole body counting, and were all found to have no internal intake. Radioactivity analysis (for Cs-134 and Cs-137) was conducted on water supplied to the mist generator, and water from the same water source as that water (water in lavatories on the 1st floor of the Main Anti-earthquake Building, water in washrooms on the 2nd floor of the Entrance Area management Building, and water in the water treatment plant). As a result, Cs-134 and Cs-137 densities in water in all of these locations were below the detection limit values (approx. 3×10^-3Bq/cm³), and sufficiently below the threshold specified in the guideline regarding radioactive materials in the bathing area (approx. 1.0×10^-2Bq/cm³). In addition, all β densities in water of these locations were measured and found to be below the detection limit values (approx. 1.3×10^-2Bq/cm³). Consequently, at 4:45 PM on the same day, the instruction not to use water for lavatories, etc. was retracted. After the alarm went off yesterday, neither the monitoring post readings nor the values indicated by the portable continuous dust monitor installed at the south side of the Main Anti-earthquake Building showed any significant change. Therefore, we consider that a local increase of dust occurred in front of the Main Anti-earthquake Building. We will investigate the cause.
*1: One-tenth of the standard value specified by the law (2.0×10^-3Bq/cm³)
*: Earlier, we stated "contamination on the 10 people found contaminated was wiped out, and the contamination levels of their bodies were confirmed to be below the internal operation management value^*2 (4Bq/cm²)" with a supplementary note "*2: One-tenth of the screening level" given as an explanation of the internal operation management value. However, this statement should be corrected to read "we confirmed that the contamination levels of the 10 people found contaminated were below the screening level (40Bq/cm²), and they were therefore allowed to leave the Entrance Area Management Building. However, so that contamination can be reliably cleared, their bodies were wiped down. At 2:13 PM on the same day, they left the Entrance Area Management Building. After the wiping down, the maximum contamination level among the 10 people found contaminated was 6.9Bq/cm^2*". Further, the supplementary note should be deleted. We apologize for the misinformation. (Corrected on August 14)

-On August 12, as an addition to the investigation on crevice corrosion, etc. of the batch treatment tank of the multi-nuclide removal equipment system A, we conducted inspections on the flange surface of a circulation tank of the system A and the flange surfaces of the absorption towers (8A and 9A), and found crevice corrosion. We also conducted an internal inspection on the absorption tower (1A) with the absorber having been pulled out of the tower, and found no corrosion, etc. Further, we conducted an internal inspection on the absorption tower (6B) of the multi-nuclide removal equipment system B with the absorber having been pulled out of the tower, and found crevice corrosion at the flange surface, and discoloration, which seems attributable to corrosion of the inner surface of the absorption tower. We will consider causes of the corrosion, measures against corrosion, and how to repair corrosion-damaged parts, and continue investigation to identify the extent of influence of the corrosion.

-At around 3:10 PM on August 12, an associated company worker, who was taking a rest at a rest area of the registration center at Fukushima Daiichi NPS, complained of his bad condition (headache and nausea), and was treated with drip infusion, etc. at the emergency medical room in the Entrance Area management Building. However, since the worker showed no sign of recovery, a doctor decided that urgent transportation to a hospital was needed. At around 4:00 PM on the same day, an ambulance was called to transport the worker to a hospital. As a result of medical examination at the hospital, he was diagnosed with a mild symptom of dehydration, and was treated with drip infusion. However, the worker has not shown recovery, and is in hospital at present.

* Revised past progress

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