Status of TEPCO's Nuclear Power Stations after the Tohoku-Chihou-Taiheiyou-Oki Earthquake (Daily Report as of 3:00 PM on August 21)

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 12, approx. 107m³ of water in the drain hole (northeast) of this underground reservoir was injected.
* Approx. 60m³, approx. 51m³, and approx. 107m³ of water were injected on August 5, 11, and 12, respectively, for the purposes of dilution and reduction of the water pressure (uplift pressure) acting on the bottom surface of the underground reservoir.

<Sampling>
On August 20, 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), the groundwater bypass investigation holes a-c (sample could not be collected at 1 out of 3 locations), the groundwater bypass pump wells No.1-No.4, and the observation holes on the sea side (1)-(4). No significant change was found with the analysis results compared to the analysis results from the sampling performed previously (on August 13 in the observation holes on the sea side (1)-(4), and on August 19 in the other locations). Further, analysis for tritium was performed on water sampled on August 12 and 13 in the groundwater bypass (investigation holes a-c and pump wells No.1-No.4; sample could not be collected at 1 investigation hole out of 3 investigation holes) and the observation holes on the sea side (1)-(8). As a result, no significant change was found compared to the previous analysis results (from the sampling on August 5 in the observation holes on the sea side (5)-(8), and on August 6 in the other locations).

- 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 γ nuclides and all-β was conducted on water in the newly installed groundwater observation hole No.1-8 (located approx. 18m east of the groundwater observation hole No.1, approx. 2m west of the ground improvement area, and approx. 7m from the bank protection) (sampled on August 20).
<Groundwater observation hole No.1-8>
Cesium-134 21Bq/L
Cesium-137 45Bq/L
All-β 1,100Bq/L

- 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 11:00 AM on the same day, the readings of the two continuous dust monitors installed in front of the Main Anti-earthquake Building fell below the point at which to give a high radioactivity level alarm. This allowed us to conduct dust sampling there, and we conducted dust sampling with a portable dust sampler (from 11:10 to 11:30 AM on the same day). As a result, cesium-134 and cesium-137 were detected at 1.2×10^-5Bq/cm³ and 3.0×10^-5Bq/cm³, respectively, indicating that the cesium densities were on the decrease. Later, we found that the reading of one of the continuous dust monitors temporarily exceeded, but soon became lower than, the point at which to give a high radioactivity level alarm. In response, we conducted dust sampling with a portable dust sampler again (from 4:09 to 4:29 PM on the same day), thereby founding out that the cesium-137 density was 8.9×10^-6Bq/cm³ and below the level at which masks are required (2.0×10^-4Bq/cm³).
As part of the investigation, we conducted dust sampling (from 12:48 to 1:08 PM and from 1:50 to 2:10 PM on the same day) in a location east of the Units 1 and 2 switching station, which was on the windward side of the Main Anti-earthquake Building when the incident occurred. As a result, cesium-134 and cesium-137 were detected.
・Sampling from 12:48 to 1:08 PM on the same day
Cesium-134: 3.2×10^-5Bq/cm³
Cesium-137: 7.2×10^-5Bq/cm³
・Sampling from 1:50 to 2:10 PM on the same day
Cesium-134: 8.0×10^-6Bq/cm³
Cesium-137: 2.1×10^-5Bq/cm³
In addition, no significant change has been found in the reading of the monitoring post-2, which was on the leeward of the Main Anti-earthquake Building. However, when we made detailed confirmation with a 1,000 times higher monitoring precision, we saw increases in the reading during the following time periods, but to the extent not measurable with the normal monitoring precision.
・From 10:00 to 10:20 AM on the same day, an increase of 42/1000μSv/h
・From 1:30 to 1:50 PM on the same day, an increase of 31/1000μSv/h
(With the normal monitoring precision, dose rates in μSv/h are measured to two significant figures.)
Further, dust sampling was conducted at the monitoring post-2 with a portable dust sampler (from 7:55 to 8:25 PM on the same day). The results of the dust sampling are as follows:
・Cesium-134: 3.1×10^-7Bq/cm³
・Cesium-137: 4.5×10^-7Bq/cm³
Please note that the above values are sufficiently low compared to the density limit in the air breathed by a radiation worker and the density limit in the air outside the surrounding monitored areas, which are specified in the public notice to determine radiation dose limits, etc. under the provisions of the regulations concerning the installment, operation, etc. of nuclear reactors for practical power generation.

Later, at appropriate points in time, we conducted dust sampling with a portable dust sampler. Provided below are results from the dust sampling inside the power station premises, including the latest results from the dust sampling in front of the Main Anti-earthquake Building.
<West of the construction area No.1 of the Main Anti-earthquake Building>
- From 11:40 AM to 12:00 PM on August 20 (sampling time and date)
Cesium-134: Below the detection limit value (the detection limit value: 3.3×10^-6Bq/cm³)
Cesium-137: Below the detection limit value (4.7×10^-6Bq/cm³)
<East of the Units 1 and 2 switching station>
- From 11:30 to 11:50 AM on August 20 (sampling time and date)
Cesium-134: 4.6×10^-6Bq/cm³
Cesium-137: 8.6×10^-6Bq/cm³
<Monitoring post-2>
- From 11:58 AM to 12:28 PM on August 20 (sampling time and date)
Cesium-134: 3.1×10^-7Bq/cm³
Cesium-137: 4.2×10^-7Bq/cm³

All of the analysis results obtained this time were found to be below the level at which masks are required (2.0×10^-4Bq/cm³).

- 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.
Later, at 7:00 PM on the same day, we started collecting water accumulated inside the dike. The water collection was carried out by pumping up the water with a temporary pump into a temporary tank, and placing absorbent inside the dike. Water collected until around 12:00 AM on August 20 amounts to approx. 4m³. In addition, the nuclide analysis results of already analyzed water samples are as follows:

<Water leaked from an H4 area tank (sampling performed at 4:00 PM on August 19)>
Cesium-134: 4.6×10¹Bq/cm³
Cesium-137: 1.0×10²Bq/cm³
Iodine-131: Below the detection limit value (the detection limit value: 3.1×10⁰Bq/cm³)
Cobalt-60: 1.2×10⁰Bq/cm³
Manganese-54: 1.9×10⁰Bq/cm³
Antimony-125: 7.1×10¹Bq/cm³
All β: 8.0×10⁴Bq/cm³
Chloride concentration: 5,200ppm

<Sand sedimentation pond (sampling performed at 3:10 PM on August 19)>
Cesium-134: Below the detection limit value (the detection limit value: 2.0×10^-2Bq/cm³)
Cesium-137: Below the detection limit value (the detection limit value: 2.6×10^-2Bq/cm³)
Iodine-131: Below the detection limit value (the detection limit value: 1.3×10^-2Bq/cm³)
Cobalt-60: Below the detection limit value (the detection limit value: 1.3×10^-2Bq/cm³)
All β: 4.1×10¹Bq/cm³

<Water of the side ditch in front of core warehouse (sampling performed at 3:00 PM on August 19)>
Cesium-134: Below the detection limit value (the detection limit value: 1.9×10^-2Bq/cm³)
Cesium-137: Below the detection limit value (the detection limit value: 2.7×10^-2Bq/cm³)
Iodine-131: Below the detection limit value (the detection limit value: 1.0×10^-2Bq/cm³)
Cobalt-60: Below the detection limit value (the detection limit value: 1.4×10^-2Bq/cm³)
All β: 1.3×10^-1Bq/cm³

We found water spread at the bottom level of tanks near the tank No.5 (H4-I-5) in the area. Therefore, we checked the water level of this tank, and found out that the water level has fallen to approx. 3m 40cm from the top of the tank. We confirmed that the current water level is lower by approx. 3m than the normal level, given that the water levels of the neighboring tanks are approx. 50cm from the top of the tanks. Further, we are checking the water levels of the surrounding tanks. Note that the amount of water corresponding to this approx. 3m fall in water level is approx. 300m³. With regards to water considered to have leaked, we started collecting the water remaining inside the dike and already collected some of the water. However, since the water seems to have flowed out of the dike through the drain valve, we will collect soil in the surrounding area and continue to conduct an investigation to find out the range reached by the water.
At 9:55 PM on August 20, we started transferring water stored in the tank No.5 in the group I in the H4 area and water collected in a temporary tank (water accumulated inside the dike) into the tank No.10 in the same area.

The latest nuclide analysis results on water are as follows:

<Seawater of the south water outlet (near the exit of the side ditch)>
- 2:20 PM on August 20 (sampling time and date)
Cesium-134: Below the detection limit value [the detection limit value: 1.1Bq/L (1.1×10^-3Bq/cm³)]
Cesium-137: 1.8Bq/L (1.8×10^-3Bq/cm³)
All β: Below the detection limit value [the detection limit value: 19Bq/L (1.9×10^-2Bq/cm³)]

<Water of the side ditch in front of the core warehouse>
- 11:40 AM on August 20 (sampling date and time)
Cesium-134: Below the detection limit value [the detection limit value: 19Bq/L (1.9×10^-2Bq/cm³)]
Cesium-137: Below the detection limit value [the detection limit value: 27Bq/L (2.7×10^-2Bq/cm³)]
All β: 93Bq/L (9.3×10^-2Bq/cm³)

As a result of the analysis this time, the densities in seawater near the exit of the side ditch of the south water outlet were found to fall within the fluctuation ranges of the past densities measured on a regular basis in seawater near the exit of the side ditch of the south water outlet. The densities in water of the side ditch in front of the core warehouse were found almost unchanged from the results obtained on August 19.
* Revised past progress

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