Status of TEPCO's Nuclear Power Stations after the Tohoku-Chihou-Taiheiyou-Oki Earthquake(Daily Report as of 3:00 PM on July 31)

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>
On June 19, since the decrease of all-β radioactivity density in the leakage detection hole (northeast) at the underground reservoirs No.1 has been slow, an operation to dilute the underground reservoir No.1 by transferring desalination-system (RO) treated water (the all-β radioactivity density: approx. 1×10¹Bq/cm³) or filtered water into the reservoir was started (the all-β radioactivity density of residual water in the underground reservoir No.1: 6.6×10⁴Bq/cm³).
[Recent dilution operation] On July 30, approx. 60m³ of filtered water was injected.

On June 27, since the decrease of all-β radioactivity density in the leakage detection hole (northeast) at the underground reservoirs No.2 has been slow, an operation to dilute the underground reservoir No.2 by transferring filtered water or desalination-system (RO) treated water (the all-β radioactivity density: approx. 1×10¹Bq/cm³) into the reservoir was started.
[Recent dilution operation] On July 31, approx. 72m³ of water was transferred to a temporary tank.

On July 24, since the decrease of all-β radioactivity density in the leakage detection hole (southwest) at the underground reservoirs No.3 has been slow, an operation to dilute the underground reservoir No.3 by transferring filtered water or desalination-system (RO) treated water (the all-β radioactivity density: approx. 1×10¹Bq/cm³) into the reservoir was started.
[Recent dilution operation] On July 30, approx. 70m³ of water was transferred to a temporary tank. On July 31, approx. 60m³ of filtered water was injected.

On July 30 and 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 July 30, 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 July 23 in the observation holes on the sea side (1)-(4), and on July 29 in the other locations). Further, analysis for tritium was performed on water sampled on July 22 and 23 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 July 15 in the observation holes on the sea side (5)-(8), and on July 16 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.

The measured all-β density in water sampled on July 29 in the groundwater observation hole No.2-1 was 380Bq/L and at about the same level as that in the groundwater observation hole No.2, showing an increase from the previous density (in water sampled on July 25), which was below the detection limit value. With regards to the other measured densities, no significant change was found compared to the previous densities.

<Measurement results obtained on July 30>
·Tritium in the groundwater observation holes No.1, No.1-2, No.1-3, No.1-4, No.2 No.3, and No.3-1 (samples taken on July 25)
·γ nuclides and all-β in the groundwater observation holes No.1, No.1-2, No.1-3, No.1-4, No.2, and No.2-1 (samples taken on July 29)
·γ nuclides and all-β in seawater inside the port (other than seawater in the Unit 1-4 water intake north side, seawater between the water intakes of Units 1 and 2 (near the surface and near the bottom), seawater at the port entrance, and seawater at the port entrance (east side and west side)) (samples taken on July 29)
·γ nuclides in the groundwater observation hole No.1-2 after filtering (a sample taken on July 29)

-At around 9:53 AM on July 30, an alarm went off indicating suspension of a booster pump and detection of leakage, and the second cesium adsorption apparatus (SARRY) was suspended. A TEPCO employee checked the site and did not find any problem such as leakage. Later, the alarm panel at the site was checked, which gave us information that the suspended booster pump was in the system B, and that an alarm indicating an abnormality of the cesium adsorption tower had been going off. Incidentally, water treatment and reactor water injection will be unaffected by the suspension of treatment operation of the second cesium adsorption apparatus (SARRY) as we have confirmed that the Central Radioactive Waste Treatment Facility (High Temperature Incinerator Building and Process Main Building used in combination) has sufficient room to receive water in transfer of accumulated water and that water to be injected into the reactors has been secured in a sufficient amount through condensate water storage tanks and the desalination system used in combination. On July 31, a detailed investigation was conducted, which revealed that this was an incident where the alarm went off due to a faulty instruction from a pressure reading transmitter placed at the absorption tower entrance and resulted in the suspension. We are scheduled to replace the pressure reading transmitter on August 1 and then start up the second cesium adsorption apparatus (SARRY). Meanwhile, the booster pump (A) has been set in the standby state so that an on-site investigation can be continued as to whether there is no problem in starting up the pump.

-At 11:10 AM on July 31, upon completion of installation of a new water injection line of the Unit 1 feed water system, we switched to the new line. At the time of the switching, the injection amount from the feed water system was adjusted from approx. 2.4m³/h to approx. 2.5m³/h. The injection amount from the reactor core spray system was maintained at approx. 1.9m³/h.

-At 2:18 PM on July 25, accumulated water transfer from the Unit 3 Turbine Building basement to the Central Radioactive Waste Treatment Facility (Miscellaneous Solid Waste Volume Reduction Treatment Building [High Temperature Incinerator Building]) was started. At 1:28 PM on July 31, the transfer was stopped due to change in the water treatment plan after operation of the second cesium adsorption apparatus (SARRY) was suspended. At 2:00 PM on the same day, transfer to the Central Radioactive Waste Treatment Facility (Process Main Building) was started.

* Revised past progress

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