Status of TEPCO's Nuclear Power Stations after the Tohoku-Chihou-Taiheiyou-Oki Earthquake (Daily Report as of 3:30 PM, April 11)

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 nuclear power stations (Fukushima Daiichi and Fukushima Daini).

* 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

-As for the underground reservoir No.2 installed within the power station site, 10¹Bq/cm³ level of radiation was detected as a result of analyzing the water accumulated between the sheet on the outside (bentonite sheet) and the ground (the underground reservoir is made of three layers of impermeable sheets) on April 3. On April 5, radiation was detected in the water between the sheet on the outside (bentonite sheet) and the sheet on the inside (double-layered permeable sheet) as a result of analysis. The radioactivity density of all β detected was approx. 5.9×10³Bq/cm³. Considering that there is no drain ditch in the surrounding area, it is considered that there is no possibility of the leaked water flowing into the sea. At 5:10 AM on April 6, the incident was judged to be a leakage which is subject to the application of Article 19-17, Item 10 of the Rule for the Installation, Operation, etc. of Commercial Nuclear Power Reactors (Rule for Commercial Nuclear Power Reactors). At 5:43 AM on April 6, we started transferring the water stored in the underground reservoir No.2 to the underground reservoir No.1 utilizing a permanent pump. Considering that the amount of leaked water is approx. 120m³, all γ radioactivity density is approx. 1.5×10⁰Bq/cm³ and all β radioactivity density is approx. 5.9×10³Bq/cm³, the γray radiation dose leaked is estimated to be approx. 1.8×10⁸Bq and the β radiation dose leaked is estimated to be approx. 7.1×10¹¹Bq. Details are currently being investigated.
As three temporary pumps were added and no problem was found with the temporary water transfer line, we started transferring the water from the underground reservoir No.2 to No.1 at 9:38 AM on the same day. In order to add another temporary pump, the pumps other than the permanent pump (3 temporary pumps) were temporarily suspended at 12:27 PM on the same day. Since no problem was found with the temporary pipeline of the newly added temporary pump, the water transfer from the underground reservoir No.2 to No.1 was started at 12:52 PM. The three temporary pumps suspended were restarted at 12:57 PM for water transfer from the underground reservoir No.2 to No.1.
In order to use the permanent facility for water transfer to the underground reservoir No.6, the water transfer to the underground reservoir No.1 was suspended at 3:33 PM on the same day. At 4:10 PM, water transfer from the underground reservoir No.2 to No.6 was started. Water transfer from the underground reservoir No.2 to No.1 utilizing temporary pumps is continued. On April 6, sampling was performed in the underground reservoirs (No.1 drain hole, No.2 leakage detection hole (northeast/southwest) and drain hole (northeast/southwest), No.3 drain hole and No.4 drain hole) as well as in the leakage detection hole (northeast/southwest) of the underground reservoir No.3.
While enhancing the monitoring of the water level of the underground reservoir No.3, on April 7, sampling was performed on the water in the drain hole (southwest) and the leakage detection hole (southwest) of the underground reservoir No.3 for the purpose of investigating the leakage location.
Considering that all β nuclides were detected in the water in the leakage detection hole and the drain hole of the underground reservoir No.3 as a result of sampling, it was judged at 8:53 AM on the same day that there may be a small amount of leakage from the impermeable sheet on the outside (bentonite sheet) of the reservoir to the outside and that the incident may be subject to the application of Article 19-17, Item 10 of the Rule for the Installation, Operation, etc. of Commercial Nuclear Power Reactors (Rule for Commercial Nuclear Power Reactors). On the same day, sampling was performed in the drain hole (northeast) and leakage detection hole (southwest: by vacuuming method^*) of the underground reservoir No.3.
On April 7, sampling was performed in the drain holes (at 14 locations) and in the leakage detection holes (sampling could not be performed at 3 out of 10 locations) of the underground reservoirs No.1-No.7. At 6:25 AM on April 8, water transfer from the underground reservoir No.2 to No.1 utilizing temporary pumps was suspended since the water level of the underground reservoir No.1 had increased.
On April 8, sampling was performed in the drain holes (at 14 locations) and in the leakage detection holes (sampling could not be performed at 2 out of 10 locations) of the underground reservoirs No.1-No.7. At 10:00 AM on April 9, water transfer from the underground reservoir No.2 to No.1 utilizing 4 temporary pumps was restarted. The samples collected in the morning of April 9 in the drain hole (at 2 locations) and the leakage detection hole (at 2 locations) of the underground reservoir No.1 have been analyzed. As a result, the chloride concentration of the water in the leakage detection hole (northeast) has increased from 4ppm (on the previous day) to 910ppm. At 12:47 PM, water transfer from the underground reservoir No.2 to No.1 utilizing temporary pumps was suspended. Considering that all βnuclides were detected as a result of sampling performed in the leakage detection hole of the underground reservoir No.1 for the purpose of investigating the leakage location, it was judged at 4:34 PM on the same day that there may be a small amount of leakage from the sheet on the inside (double -layer impermeable sheet) to the impermeable sheet on the outside (bentonite sheet) of the reservoir and that the incident may be subject to the application of Article 19-17, Item 10 of the Rule for the Installation, Operation, etc. of Commercial Nuclear Power Reactors (Rule for Commercial Nuclear Power Reactors) although the water level of the underground reservoir No.1 has not decreased and the analysis results of the drain hole water of the underground No.1 have not yet been confirmed.
In the morning on April 9, sampling was performed in the drain hole (northeast, southwest) and the leakage detection hole (southwest) of the underground reservoir No.1.
In the afternoon on April 9, sampling was performed in the drain hole (northeast, southwest) and the leakage detection hole (northeast, southwest) of the underground reservoir No.1.
Also, sampling was performed in the drain holes of the underground reservoirs No.2-7 (at 12 locations) and the leakage detection holes of the underground reservoirs No.2-4 and 6 (sample could not be collected at 2 out of 8 locations). As a result, no significant change was found compared to the results obtained on April 8.
On April 10, sampling was performed in the groundwater bypass pump wells No.1-4 located in the east of the underground reservoirs No.1-3 for the purpose of evaluating the impact of the contaminated water leakage from the underground reservoirs on the surrounding environment. As a result, no radioactive material was detected.
On the same day, in order to prevent the leaked water in the leakage detection hole of the underground reservoir No.1 from leaking into the ground in the surrounding area, the temporary pump was put in operation from 3:40 PM to 3:41 PM (approx. 1 minute) in the northeast side of the leakage detection hole and at 4:05 PM (approx. 30 seconds) in the southwest side of the leakage detection hole to return the leaked water to the underground reservoir. Also, the soil covering the leakage detection hole (northeast) penetration of the underground reservoir No.2 was removed to perform a visual inspection of the penetration. The removal of the impermeable sheet, gravels, etc. will continue on April 11 and later. Furthermore, equipment installation and trial drilling were performed to prepare for the boring investigation to confirm the contamination condition of the surrounding area of the underground reservoirs and contamination expansion to the sea side. The work will be continued on April 11 and later.
As a result of analyzing the sampling results (chloride concentration and allβ) performed on April 10 in the drain holes of the underground reservoirs No.1-7 (at 14 locations) and the leakage detection holes of the underground reservoirs No.1-4 and 6 (sample could not be collected at 2 out of 10 locations), no significant change in the chloride concentration and allβwas found compared to the results obtained on the previous day (April 9).
The water transfer from the underground reservoir No.2 to No.6 which had been performed since 4:10 PM on April 6 was suspended at 1:06 PM on April 11 as scheduled. Though water transfer from the underground reservoir No.3 to No.6 was started at 2:00 PM on the same day, the transfer pump was stopped at 2:03 PM as water leakage from the connection part (flange) of the transfer pump outlet pipe was found. The leakage stopped after stopping the transfer pump. The area affected by the leakage was 2m x 3m on the soil (embankment) covering the upper part (near the manhole) of the underground reservoir No.3. Since the leaked water was absorbed into the covering soil, there is no possibility of the leaked water flowing out of the site boundary. The amount of leakage (calculation value) is assumed to be approx. 22L. Though the incident has occurred in the controlled area, the condition has been judged to be subject to the application of Article 19-17, Item 10 of the Rule for the Installation, Operation, etc. of Commercial Nuclear Power Reactors (Rule for Commercial Nuclear Power Reactors) ("in the case that leakage of radioactive materials, etc. occurs in the controlled area due to a reactor facility failure or other unexpected incidents") at 2:35 PM^*1 on April 11. This incident is reported in accordance with Article 168 of the Technical specification for nuclear reactor facility at Fukushima Daiichi Nuclear Power Station (Report).
< Reference: Underground reservoir No.3 >
Water quality analysis result: 2.9×10⁵Bq/cm³
Leakage amount: Approx. 22L
Value stipulated by law: 3.7×10⁶Bq
*Vacuuming method: A method to collect samples by utilizing a suction machine and a hose.

-On April 11, sampling was conducted at the charcoal filter and the particulate filter of Unit 3 PCV gas control system.^*2

-On April 11, dust sampling was performed in the upper part of Unit 3 Reactor Building.^*2

-At 3:38 PM on April 10, Unit 3 reactor injection water amount was adjusted as follows since the amount had decreased.
Feed water system: increased from approx. 1.9m³/h to approx. 2.0m³/h, reactor core spray system: increased from approx. 3.3m³/h to approx. 3.5m³/h.

-At 12:50 PM on April 11, Units 1-3 reactor injection water amounts were adjusted as follows since the amounts were confirmed to have decreased at 12:10 PM due to the switching of the regular reactor water injection pump on the hill.
[Unit 1] Feed water system: increased from approx. 2.4m³/h to approx. 2.5m³/h, reactor core spray system: maintained at approx. 2.0m³/h.
[Unit 2] Feed water system: increased from approx. 1.8m³/h to approx. 2.0m³/h, reactor core spray system: increased from approx. 3.4m³/h to approx. 3.5m³/h.
[Unit 3] Feed water system: increased from approx. 1.9m³/h to approx. 2.0m³/h, reactor core spray system: increased from approx. 3.4m³/h to approx. 3.5m³/h.

[Fukushima Daini Nuclear Power Station]
·Unit 1 to 4: Shutdown due to the earthquake.

*1 Regarding the water leakage from the connection part (flange) of the transfer pump outlet pipe which occurred at 2:03 PM on April 11 during the water transfer from the underground reservoir No.3 to No.6 which started at 2:00 PM on the same day, it said in the daily report previously announced that the incident was judged to be subject to application of Article 19-17, Item 10 of the Rule for the Installation, Operation, etc. of Commercial Nuclear Power Reactors (Rule for Commercial Nuclear Power Reactors) at "2:43 PM on April 11". However, the time has been corrected to "2:35 PM on April 11". We apologize for the mistake. (Corrected on April 15, 2013)

*2 In the daily report previously announced, the updates on the sampling performed at the charcoal filter/particulate filter of Unit 3 PCV gas control system and in the upper part of Unit 3 Reactor Building were missing. We apologize for the mistake. (Corrected on April 21, 2013)

* Revised past progress

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