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

-At around 8:20 AM on July 18, an associated company worker, investigating the site using a camera ahead of debris removal work, encountered a steam-like gas wafting through the air near the central part of the fifth floor (equipment storage pool side) of Unit 3 Reactor Building. No significant change was found in the main parameters related to the plant (temperature, pressure and xenon density of PCV/RPV). Neither was any significant fluctuation found in the monitoring post readings or the continuous dust monitor amounts. At 9:20 AM on the same day, the subcritical state was found being maintained. With regards the measurement result of ambient dose on the upper part of the spent fuel pool protection at Unit 3 Reactor Building, no remarkable change was found compared to the measurement result so far obtained every day before work. We are planning to measure ambient dose in a space over Unit 3 Reactor Building and conduct dust sampling near that space.

-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) 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 5, approx. 40m³ 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 into the reservoir was started.
[Recent dilution operation] On July 17, approx. 40m³ of desalination-system (RO) treated water was injected.

<Sampling>
Analysis was conducted on water taken on July 17 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). Among the analysis results, the chloride concentration and all-β density in water of the leakage detection hole (northeast) of the underground reservoir No.2 showed decreasing trends compared to the analysis results from the sampling previously performed (on July 16). This is considered attributable to the dilution that is currently underway. The other analysis results showed no significant change compared to the previous results. Further, analysis for tritium was conducted on water taken on July 10 in the drain holes and leakage detection holes of the underground reservoirs No.1-No.4 and No.6. The analysis results showed no significant change compared to the previous results (from sampling performed on July 3)

-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.

* Revised past progress

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