Status of TEPCO's Nuclear Power Stations after the Tohoku-Chihou-Taiheiyou-Oki Earthquake (Daily Report as of 4:00 PM on August 19)

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 18, 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 18, 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 other analysis results showed no significant change compared to the results from the previous sampling (on August 17).

- 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 around 10:04 AM on August 19, an alarm indicating the high-high radioactivity level went off at the continuous dust monitor installed in front of the Main Anti-earthquake Building. Due to this, at 10:15 PM on the same day, an instruction was given to wear masks in the areas, within the power station site, where wearing full-face (or half-face) masks is not required. Neither abnormality on the plant data (reactor injection water amount, spent fuel pool water temperature, etc.) nor significant change in the monitoring post data has been found. Also, no significant change has been found in the readings of continuous dust monitors installed at locations other than the Main Anti-earthquake Building. For these reasons, we consider that this incident has no impact on the outside of the power station. In addition, from the two continuous dust monitors installed there, an alarm indicating the high radioactivity level went off at around 9:29 AM (from one of the monitors) and at around 9:34 AM (from the other monitor) on the same day. In response, we conducted dust sampling with a portable measurement device in front of the Main Anti-earthquake Building from 9:50 to 10:10 AM. As a result of γ nuclide density measurement, cesium-134 and cesium-137 were detected at 2.6×10^-4Bq/cm³ and at 5.8×10^-4Bq/cm³, respectively, indicating that the cesium densities have increased. Incidentally, the instruction to wear masks in the areas within the power station site where wearing full-face (or half-face) masks is not required has been kept in force. Meanwhile, at around 10:20 AM on the same day, the contamination measurement conducted through the exit monitor at the Entrance Control Facility found out that 2 people, out of those who had been waiting for a bus in front of the Main Anti-earthquake Building, had their bodies contaminated. Contaminated sections on the 2 people found to have their bodies contaminated were the upper parts of their heads alike, and the maximum dose was 13Bq/cm². This is below the screening level (40Bq/cm²), and they were therefore allowed to leave the Entrance Control Facility. However, their bodies were cleaned of contamination by being wiped down, etc, and then, at 10:56 AM on the same day, they left the Entrance Control Facility. Later, they underwent whole body counting, which indicated that they have no internal intake.

- At around 9:50 AM on August 19, a TEPCO employee on patrol found water leaking from a drain valve of a tank dike in the H4 area in the power station. Later, the drain valve was closed. No significant change has been found in the monitoring post readings. As a result of confirmation on the site conditions, a puddle of approx. 1-2cm was found inside the dike, and puddles of approx. 3m×3m×1cm and approx. 0.5m×6m×1cm were found outside of the drain valve of the dike. There is no trace of water having flowed into a public drainage ditch, etc. from the puddles found outside of the drain valve of the dike. Therefore, we consider that the water has not flowed out into the sea.
At 2:28 PM on August 19, we determined that this incident corresponds to "a case when nuclear fuel material (not in the form of gas) or the like has leaked within an area controlled by the company due to an unpredictable event such as a failure of a nuclear reactor facility for power generation" as per Article 18, item 12 of the regulations concerning the operational safety and the protection of specified nuclear fuel material at the TEPCO's Fukushima Daiichi NPS nuclear reactor facilities. The reasons for the determination are as follows:
·Although we have not yet been able to identify the source of contaminated water, water accumulated inside the dike around a tank containing contaminated water has leaked outside the dike through the drain valve.
·It cannot be denied that water stored in a tank has leaked from the tank.
·High β ray and γ ray densities were detected in the puddle of water having leaked outside the dike It cannot be denied that water stored in a tank has leaked from the tank.

- At 1:57 PM on August 19, the secondary system of the Unit 4 spent fuel pool alternative cooling system was suspended since it was required to perform an operation to pass a minute amount of water on the air fin cooler of the secondary system of the spent fuel pool alternative cooling system. Later, at 2:40 PM on the same day, the secondary system of the spent fuel pool alternative cooling system was started up after the operation was completed. No abnormality has been found in its operation status after the startup. The spent fuel pool water temperature has remained unchanged at 37℃ since the suspension of cooling. The temperature has been thus sufficiently low compared to the operational limit value of 65℃, and no problem has occurred in controlling the spent fuel pool water temperature.

* Revised past progress

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