Status of TEPCO's Nuclear Power Stations after the Tohoku-Chihou-Taiheiyou-Oki Earthquake (Daily Report as of 3:00 PM on September 1)

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.

·On August 31, 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 31, 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 no significant change compared to the results from the previous sampling (on August 30).

- 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.

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. Later, we found streaky traces of flows on the wall surface of a drainage channel located east of the H4 area tanks. In response, we measured surface dose equivalent rates at this location, and the maximum rate was 6.0mSv/h (γ and β rays (70μm dose equivalent rate)). As this information indicates the possibility that contaminated earth and sand, etc. may have flowed into the drainage channel, we are planning to conduct a detailed investigation and evaluation concerning these traces. Incidentally, we confirmed that no water was flowing on the surface of the ground near the above drainage channel at the time when water leaking this time was found.

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. At 9:13 PM on August 21, we completed the transfer of the water stored in the tank No.5. At 3:00 PM on August 22, we completed the transfer of the water collected in a temporary tank.

From around 11:00 AM to around 3:00 PM on August 22, we conducted full inspections (appearance inspections and dose measurement) on the flanged tanks in the other areas, which are of the same type as the tank from which water has leaked. Neither leak nor puddle was found by the appearance inspections on the tanks and the drain valves. However, 2 locations locally showing high dose rates were found around the H3 area tanks. The surfaces of these locations were dry, and we confirmed that there has been no water having flowed into the inside of the dike or the outside of the dike. We also confirmed that the water levels of these tanks remain unchanged after they received water.
[High dose rate locations, the surface dose equivalent rates at these locations (γ and β rays (70μm dose equivalent rate)), and tank water levels]
·Near the bottom flange of the tank No.4 in the group B in the H3 area: 100mSv/h and approx. 97% of the full water level
·Near the bottom flange of the tank No.10 in the group A in the H3 area: 70mSv/h and approx. 95% of the full water level
No locations around the other tanks and drain valves showed high dose rates.
We conducted nuclide analysis on water from the tank (hereinafter "Tank") No.5 in the group (hereinafter "Group") I in the H4 area from which water has leaked. Based on the analysis results shown below, we confirmed that water from this tank is RO concentrated water.
<Water from Tank No.5 in Group I in the H4 area (sampling performed at 9:00 PM on August 23)>
Cesium-134: 4.4×10¹Bq/cm³
Cesium-137: 9.2×10¹Bq/cm³
Antimony-125: 5.3×10¹Bq/cm³
All β: 2.0×10⁵Bq/cm³
Chloride concentration: 5,200ppm

Additionally, we conducted full inspections (visual appearance inspections and water level confirmation) on the flanged tanks that are in use for storage of accumulated water from Units 5 and 6. The inspections were completed on August 26 and showed no abnormality.

During our inspection of Tank No.5 in Group I in the H4 area from which water has leaked, we found out the following:
·3 tanks including this tank (Tank No.5 in Group I, Tank No.10 in Group I, and Tank No.3 in Group II in the H4 area) were initially installed in the H1 area.
·Ground subsidence occurred in the H1 area at the foundations on which these tanks had been placed, and these tanks were planned to be installed in the H2 area, but actually, have been placed in the H4 area despite our plan.
Although it is still unclear whether there is a causal relationship between the water leaking of Tank No.5 and the tank's having experienced ground subsidence occurred in the H1 area at the foundation on which it had been placed, we started to transfer water from inside Tank No.10 in Group I in the H4 area to Tank No.10 in Group B in the H4 area at 3:57 PM on August 25 to reduce the risk of leakage. At 2:07 AM on August 27, the transfer was completed. Further, at 10:30 AM on August 29, we start to transfer water from inside Tank No.3 in Group II in the H4 area to Tank No.10 in Group B in the H4 area. At 4:50 PM on the same day, water transfer to Tank No.10 in Group B, within the H4 area, was temporarily suspended (This is because the approach of Typhoon No.15 this weekend is expected to leave rainwater accumulated inside the dikes, and Tank No.10 in Group B in the H4 area may be used as a tank into which accumulated rainwater, if any, will be transferred.).

During a patrol today (on August 31), we found 4 locations showing high dose equivalent rates (γ and β rays (70μm dose equivalent rate)). We consider that there has been no leakage to the outside of the dike because the water levels of all of the relevant tanks have not decreased and also because the drainage valves have been closed. The dose equivalent rates in these locations are as follows.

·The floor surface of the connecting pipe section between Tank No.5 and Tank No.6 in Group IV in the H5 area: Approx. 230mSv/h (70μm dose equivalent rate)

·Near the bottom flange of Tank No.10 in Group A in the H3 area: Approx. 220mSv/h (70μm dose equivalent rate)
(This is the same location as the location that showed approx. 70mSv/h when the tanks were inspected on August 22.^*1)

·Near the bottom flange of Tank No.4 in Group B in the H3 area: Approx. 1,800mSv/h (70μm dose equivalent rate)
(This is the same location as the location that showed approx. 100mSv/h when the tanks were inspected on August 22.^*1)

·The bottom of Tank No.6 in Group II in the H4 area: Approx. 70mSv/h (70μm dose equivalent rate)
*1: These are locations where we measured the rates on August 22 and measured the rates again today (on August 31). The cause of the differences in values will be investigated.

With regards to the floor surface of the connecting pipe section between Tank No.5 and Tank No.6 in Group IV in the H5 area, the heat insulation material of the pipe placed above the floor surface was pressed after the high dose equivalent rate (not less than 100mSv/h (70μm dose equivalent rate)) was detected during a patrol. Then, one drop of water fell to the floor surface. The dose equivalent rate at a location on the floor surface to which the water fell was measured and confirmed to be approx. 230mSv/h (70μm dose equivalent rate). Although water then stopped dropping from the connecting pipe, a discolored part (in a dry condition) was found on the floor surface under the pipe section. The size of this part was approx. 20cm×20cm. High dose equivalent rates were not detected in locations on the floor surface that are apart from the discolored part. As emergency action concerning this location, we placed a drain pan at the discolored part on the floor surface, and wrapped the connecting pipe with an absorption mat. With regards to the other locations in the H3 and H4 areas, we confirmed that there has been no continuous water dropping.

We checked the status of water dropping from the connecting pipe between Tank No.5 and Tank No.6 in Group IV in the H5 area with the heat insulation material and absorption mat having been pulled out. At around 11:10 PM yesterday (on August 31), we found out that a flange part connecting an isolation valve on the Tank No.5 side (there are 2 isolation valves connecting these tanks and connecting pipe) and the connecting pipe was dripping one drop per approx. 90 seconds. Later, we wrapped the adsorption mat around this flange part and covered it with plastic-sheet protection, while placing a drain receiving pan under the flange part on the floor. Both of the 2 isolation valves on the respective Tanks No.5 and No.6 sides of this connecting pipe were found to be closed.

Following this leakage from a tank, we sampled water in the following locations and conducted nuclide analysis on the water (sampled on August 31). The analysis results are as follows. No remarkable change was found in the analysis results compared to those obtained the day before (in the samples taken on August 30).

<Seawater near the south water outlet (near the exit of the drainage channel)>
(Sampled at 10:40 AM on August 31)
Cesium-134: Below the detection limit value [the detection limit value: 1.3Bq/L (1.3×10^-3Bq/cm³)]
Cesium-137: Below the detection limit value [the detection limit value: 1.5Bq/L (1.5×10^-3Bq/cm³)]
All β: Below the detection limit value [the detection limit value: 22Bq/L (2.2×10^-2Bq/cm³)]

<Water at the junction of the drainage channels B and C near the H4 area (previously referred to as "water of the side ditch in front of the core warehouse")>
(Sampled at 11:13 AM on August 31)>
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: 25Bq/L (2.5×10^-2Bq/cm³)]
All β: 200Bq/L (2.0×10^-1Bq/cm³)

<Water in the drainage channel B near Fureai Intersection>
(Sampled at 1:20 PM on August 31)
Cesium-134: Below the detection limit value [the detection limit value: 19Bq/L (1.9×10^-2Bq/cm³)]
Cesium-137: 26Bq/L (2.6×10^-2Bq/cm³)]
All β: 43Bq/L (4.3×10^-2Bq/cm³)

<Water in the drainage channel C near the main gate>
(Sampled at 1:32 PM on August 31)
Cesium-134: Below the detection limit value [the detection limit value: 18Bq/L (1.8×10^-2Bq/cm³)]
Cesium-137: Below the detection limit value [the detection limit value: 26Bq/L (2.6×10^-2Bq/cm³)]
All β: Below the detection limit value [the detection limit value: 14Bq/L (1.4×10^-2Bq/cm³)]

<Water at the drainage channel C OP. 30m exit>
(Sampled at 11:00 AM on August 31)
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: 26Bq/L (2.6×10^-2Bq/cm³)]
All β: 210Bq/L (2.1×10^-1Bq/cm³)

We detected no remarkable changes in three points in the drainage channel B, compared to the results detected on August 22.

<Drainage channel B (where high dose rate was detected on August 21(B-1))>
(Sampled at 11:44 AM on August 31)
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: 26Bq/L (2.6×10^-2Bq/cm³)]
All β: 32Bq/L (3.2×10^-2Bq/cm³)

<Drainage channel B (downstream of B-1)>
(Sampled at 11:35 AM on August 31)
Cesium-134: Below the detection limit value [the detection limit value: 20Bq/L (2.0×10^-2Bq/cm³)]
Cesium-137: Below the detection limit value [the detection limit value: 32Bq/L (3.2×10^-2Bq/cm³)]
All β: 480Bq/L (4.8×10^-1Bq/cm³)

<Point before reaching the junction of the drainage channels B and C (upstream of the junction)>
(Sampled at 11:23 AM on August 31)
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: 920Bq/L (9.2×10^-1Bq/cm³)

We conducted analysis of water in the groundwater bypass pump wells No.11 and No.12. The results are as follows. The results of tritium density sampled at No.11 in February 2013 as a preparation for operating groundwater bypass was 57Bq/L, and the result of tritium density No.12 was 450Bq/L. These densities are far below the legal announcement density (60,000Bq/L).

<Pump well No.11>
(Sampled on August 30)
Tritium: 300Bq/L
All β: Below the detection limit value (16Bq/L)

<Pump well No.12>
(Sampled on August 30)
Tritium: 900Bq/L
All β: Below the detection limit value (16Bq/L)

At around 10:04 AM on August 19, the high-high radioactivity alarm at a continuous dust monitor installed in front of the Main Anti-earthquake Building was issued. Therefore, at 10:15 AM on the same day, workers were warned to wear masks in the no full-face (half-face) masks areas. On August 29, after an anti-scattering agent was sprayed, debris removal work in the upper part of Unit 3 Reactor Building was temporarily conducted from 1:15 to 2:03 PM, and dust sampling was performed in the upper part of Unit 3 in the meantime. The anti-scattering agent was spayed also after the removal work. As a result, the maximum cesium density in the upper part of Unit 3 Reactor Building was 1.7×10^-2Bq/cm³, which is 7 times higher than the density obtained from the sampling performed on August 22 while debris removal work was not being conducted. Based on these results, we confirmed that debris removal work in the upper part of Unit 3 Reactor Building causes radioactive material densities in air to increase. In the meantime, as a result of the dust sampling within Fukushima Daiichi NPS, we confirmed that the in-air densities of radioactive materials on dust increased at the slope near Units 3 and 4 and at the cooperative company building, which were on the leeward of Unit 3 Reactor Building. However, even at the slope near Unit 3 and 4 located the nearest from the Unit 3 Reactor Building, the cesium-134 density was 3.1×10^-6Bq/cm³, and the cesium-137 density was 9.1×10^-6Bq/cm³ . The densities are far below the criterion (2.0×10^-4Bq/cm³) for requiring that full-face (half-face) masks be worn, and also far below the criterion (1.0×10^-4Bq/cm³) for a continuous dust monitor to give an alarm [high-high radioactivity alarm] indicating a high radioactivity density. Given that the radioactive density in the air in the electric power plant became sufficiently below the criterion for requiring that full-face (half-face) masks be worn, we started an operation to add dust respirators (DS2/N95) to masks worn in no-mask areas at 12:00 AM on September 1.

- 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 and have been pumping up groundwater at the well point and the water collection point in the east of Unit 1 and Unit 2 Turbine Buildings.

<The latest groundwater transfer operation>
At 3:50 PM on August 31, the water transfer to the Unit 2 vertical shaft C from the well point and the water collection pit (south) was suspended, and the water transfer to the Unit 2 Turbine Building was performed at 3:55 PM.

At 2:55 PM on August 22, in order to close the trench, transfer of contaminated water in the Unit 2 branch trench (vertical shaft B and power cable trench) in the east of the Unit 2 Turbine Building to the Unit 2 Turbine Building was started. At 1:16 PM on August 24, the transfer was suspended. We completed all the transfer. From at 1:03 to 3:32 PM on August 31, accumulated water (water collected for closing the Trench) inside the Unit 2 vertical shaft B was transferred to the Unit 2 Turbine Building.

- At around 9:45 on August 30, an associated company worker, who was then transferring drum cans in the F tank area at Unit 6, complained of his bad condition. Therefore, he was examined by a doctor at the emergency medical room of the Entrance Area Management Building. Since the doctor judged that the worker needs to be transported urgently to a hospital, an ambulance was called at around 10:46 AM on the same day. At 12:20 PM, the worker was transferred to Iwaki City Iwaki-Kyoritsu General Hospital and was accumulated for the hospital for a medical checkup.

* Revised past progress

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