Status of TEPCO's Nuclear Power Stations after the Tohoku-Chihou-Taiheiyou-Oki Earthquake (Daily Report as of 3:00 PM on September 18)

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 September 17 and 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 Results>
On September 17, 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), groundwater bypass observation holes a - c (sample could not be collected at 1 of the 3 locations), groundwater bypass pumping wells No.1-No.4, and seaside observation holes (1) - (4). No significant change was found in the analysis results compared to the analysis results on the previous samples (samples for groundwater bypass observation holes a - c (sample could not be collected at 1 of the 3 locations), groundwater bypass pumping wells No.1-No.4, and seaside observation holes (1) - (4) were taken on September 10, the rest taken on September 16).
There were no significant changes in the tritium analysis results from the sample taken from September 9 to September 10 at the groundwater bypass observation holes a - c (sample could not be collected at 1 of the 3 locations), groundwater bypass pumping wells No.1-No.4, and seaside observation holes (1) - (8) when compared to the previous results (seaside observation holes (5) - (8) taken on September 2, the rest taken on September 3).

-On August 19, puddles were found inside a dike around the H4 area tanks in the power station and outside of a drain valve of the dike.
We found water spread at the bottom level of tanks near Tank No.5 in the Group I in the H4 area. Therefore, we checked the water level of this tank, and found out that the water level has fallen by approx. 3m than the normal level (the amount of water: approx. 300m³). We started collecting the water remaining inside the dike and already collected some of the water. However, since it seemed that the water has flowed out of the dike through the drain valve, we are collecting soil in the surrounding area and continuing 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. The maximum surface dose equivalent rate measured at this location 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.

On August 22, transfer of water stored in Tank No.5 in Group I in the H4 area and water collected in a temporary tank (water accumulated inside the dike) into Tank No.10 in Group B in the H4 area was completed.

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. Additionally, we conducted soundness 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 conducted water transfer from inside Tank No.3 in Group II in the H4 area to Tank No.10 in Group B in the H4 area to reduce the risk of leakage.
<The latest transfer operations>
· At 3:57 PM on August 25, transfer from Tank No. 10 in Group I in the H4 area to Tank No. 10 in Group B in the H4 area was started. At 2:07 AM on August 27, the transfer was completed.
· At 10:30 AM on August 29, transfer from Tank No. 3 in Group II in the H4 area to Tank No. 10 in Group B in the H4 area was started. At 11:03 AM on September 2 water transfer was suspended due to the implementation of rainfall countermeasures.

During a patrol 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.
One of the 4 locations, the connecting pipe section between Tank No.5 and Tank No.6 in Group IV in the H5 area has the heat insulation material placed in the upper part of the pipe, and one drop of water fell to the floor surface when this heat insulation material was pressed. 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. Although water then stopped dropping from the connecting pipe, a discolored part (in a dry condition) of approx. 20cm×20cm was found on the floor surface under the pipe section. Then, 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 having been pulled out. Then, 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. In response, on the same day, 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 have been closed. On September 1, we tightened up 12 flange bolts at this flange part, and we confirmed that no water leakage was occurring. For the confirmation purpose, the water levels of Tank No.5 and Tank No.6, in Group IV in the H5 area, were measured and found unchanged.
<Results of the latest patrol>
During a patrol on September 17, no location showed a high dose equivalent rate (β and γ rays (70μm dose equivalent rate)). Locations near the dike floor continued to show low dose equivalent rates since rainwater accumulated inside the dike (approx. 3 to 4 cm deep) worked as a shield. Additionally, we conducted a visual inspection, and all of the tanks were found without any abnormality such as leakage (expect for the leaks that resulted in accumulated water inside the dike).

As a result of the full inspections (appearance inspections and dose measurement) conducted on August 22 on the tanks in the areas other than the H4 area, we found tanks (Tank No.4 in Group B and Tank No.10 in Group A, both in the H3 area) each having a part locally showing a high dose rate. Although no water dropping was found on the outside of these tanks, we have been transferring water inside the tanks to an RO waste liquid supply tank since August 29.

Following the leakage from a tank this time, we sampled water at the Fukushima Daiichi at the point near the south water outlet (T-2), at the junction of the drainage channels B and C near the H4 area (C-1),at the point of high dose rate measurement in the B drainage channel (B-1), downstream from B-1 (B-2), at the point immediately short of the junction with the drainage channel C (B-3), at the point near Fureai Intersection in the drainage channel B (B-0-1), at the point near the main gate in the drainage channel C (C-0), and at the drainage channel C OP. 35m exit (C-2) (sample taken on September 17), and conducted nuclide analysis on the water.. The analysis results showed no significant changes when compared with the previous results (sample taken on September 16).

We conducted analysis for all-β and tritium on water in observation holes (E-1: on the north of the dike that surrounds tanks including Tank No.5 in Group I in the H4 area from which water has leaked, E-2: on the south of the dike that surrounds tanks including Tank No.5 in Group I in the H4 area from which water has leaked) newly installed near the H4 area tanks.

With regards the groundwater observation hole (E-1) around the H4 area, tritium in the sample taken on September 16 was detected at 95,000Bq/L, which is decreased compared to 140,000Bq/L in the sample taken on September 15. With regards to the observation hole (E-2) area around the H4 area, the analysis from September 16 resulted in a value about the same as that in the tritium sample taken on September 15.
Although the tritium analysis results conducted on September 15 for the observation hole (E-4) around the H4 area were less than the detectable limit (detectable limit: 120Bq/L), the analysis results for the sample taken on September 16 were 410Bq/L, and will thus continue to be monitored.
The analysis results for the all-β sample taken on September 17 at the observation holes around the H4 area (E-1, E-2, E-4) showed no significant changes when compared with the previous results taken on September 16.

The all-β analysis results newly conducted on September 17 for groundwater bypass pump well No.5 and No.6 were less than the detectable limit (detectable limit: 15Bq/L). The all-β analysis results conducted on September 17 for other groundwater bypass pump wells No.7-No.12 were also less than the detectable limit (detectable limit: 15Bq/L).

Dismantling of the H4 area I group No.5 tank with verified leak began on September 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 and have been pumping up groundwater at the well point and the water collection pit (south) on 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 points and the water collection pit (south) was suspended, and the water transfer to the Unit 2 Turbine Building was started at 3:55 PM on August 31.
So that water in the Unit 2 vertical shaft B (water collected due to the closure of the trench) could be transferred to Unit 2 Turbine Building during the daytime from September 3, groundwater transfer from the well points and the water collection pit (south) was conducted while the transfer destination was sequentially changed. The work of closing the trench was almost completed, and transfer of groundwater in the well points and the water collection pit (south) to Unit 2 Turbine Building has been underway from September 7.

* Steam was verified by a camera around 8:00 AM on September 18 around the center area (equipment storage pool side) of the 5th floor of the Unit 3 reactor building. No abnormalities were found in the monitoring post indicated values or the plant situation, verified by 8:10 AM on the same day (weather data at 8:00 AM: temperature 21.7℃, humidity 82.9%). Around 10:00 AM on September 18 steam was no longer verified. No abnormalities were found in the plant situation or monitoring post indicated values at 10:15 AM (weather data at 10:00 AM: temperature: 24.0℃, humidity: 58.4%).

* It was discovered at 1:15 PM on September 17 by an employee that water (fresh water being received from the Sakashita dam) was leaking from pure water filtration facility's raw underground water tank. Leaking water was flowing to the close by drainage gutter. The leak was stopped by closing the receiving piping valve of the said tank.
Upon investigation, the employee found that after opening the inlet valve (manual valve) to receive Sakashita dam water to the raw underground water tank, water level monitoring using the control panel was neglected due to performing other work. The tank filled up with water, and the leak was found. The amount of leaked water is estimated to be approx. 20m³

* In order to conduct exhaust pipe seismic safety evaluation for Units 1 and 2 on September 18, a field investigation was held in order to verify damage such as rust, broken areas, areas that look like they are breaking, and steel materials (diagonal bracing) of the exhaust pipe. Due to the exhaust pipe area having high dosage rate points, plans to begin investigations after deliberation of detailed investigation methods. The said exhaust pipe is currently not being used. There have also been no plant data (reactor pressure vessel bottom temperature, containment vessel temperature) abnormalities or significant changes in the monitoring post indicated values verified.

* Revised past progress

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