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Press Release (Apr 19,2011)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 6:00 pm, April 19)
 
*Updates are underlined
 
All 6 units of Fukushima Daiichi Nuclear Power Station have been shut down.
 
Unit 1 (Shut down) -Explosive sound and white smoke were confirmed after the big quake occurred at 3:36 pm on March 12th. It was assumed to be hydrogen explosion. -At approximately 2:30 am on March 23rd, seawater injection to the nuclear reactor through the feed water system was initiated. -From 3:37 pm on March 25th, we started injecting freshwater and are now injecting fresh water by a motor driven pump powered by the off-site transmission line. -As it is suspected that hydrogen gas is accumulated inside reactor containment vessel, we commenced the valve opening operation concerning injection of nitrogen gas into the reactor container vessel at 10:30 pm April 6th and commenced injection at 1:31am April 7th.
 
Unit 2(Shut down) -At approximately 6:00 am on March 15th, an abnormal noise began emanating from nearby Pressure Suppression Chamber and the pressure within the chamber decreased. -From 10:10 am on March 26th, we started injecting freshwater to the reactor and are now injecting fresh water by a motor driven pump powered by the off-site transmission line. -From 7:35 pm on April 12th, we started transferring the high level radioactive accumulated water in the trench of the turbine building to the condenser by an underwater pump. At 5:04pm on April 13th, the scheduled transfer was completed.
 
Unit 3(Shut down) -Explosive sound and white smoke were confirmed at approximately 11:01am on March 14th. It was assumed to be hydrogen explosion. -From 6:02 pm on March 25th, we started injecting fresh water to the reactor and are now injecting fresh water by a motor driven pump powered by the off-site transmission line.
 
Unit 4 (outage due to regular inspection) -At approximately 6:00 am on March 15th, we confirmed the explosive sound and the sustained damage around the 5th floor rooftop area of the Nuclear Reactor Building. -At this moment, we do not consider any reactor coolant leakage inside the reactor happened.
 
Unit 5 (outage due to regular inspection) -Sufficient level of reactor coolant to ensure safety is maintained. -At 5:00 am on March 19th, we started the Residual Heat Removal System Pump (C) in order to cool the spent fuel pool. -At 2:30 pm on March 20th, the reactor achieved reactor cold shutdown. At around 5:24 pm on March 23rd, when we switched the temporary Residual Heat Removal System Seawater Pump, it has stopped automatically. At around 4:14 pm on March 24th we replaced the pump, and restarted cooling of reactor at around 4:35 pm. -At this moment, we do not consider any reactor coolant leakage inside the reactor happened.
 
Unit 6 (outage due to regular inspection) -Sufficient level of reactor coolant to ensure safety is maintained. -At 10:14 pm on March 19th, we started the Residual Heat Removal System Pump (B) of Unit 6 in order to cool the spent fuel pool. -At 7:27 pm on March 20th, the reactor achieved reactor cold shutdown. -In relation to the two seawater side pumps of the Residual Heat Removal System, we switched the power source from temporary to permanent at 3:38 pm and 3:42 pm, Mar 25 respectively. -From 11:00 am to 3:00 pm on April 19th, we transferred water accumulated at the underground level of the nuclear reactor building of Unit 6 to measure volume of the accumulated water. -At this moment, we do not consider any reactor coolant leakage inside the reactor happened.
 
Operation for cooling the spent fuel pools -From 10:17 am to 11:35 am on April 19th, we have sprayed water to Unit 4 by a concrete pump vehicle. -From 4:08 pm to 5:28 pm on April 19th, we injected fresh water by a motor driven pump powered by the off-site transmission line. -We will conduct further water spray depending on the conditions of spent fuel pools, if needed.
 
Others -The national government has instructed evacuation for those local residents within 20km radius of the periphery and shelter in place for those residents from 20km to 30km radius of the periphery, because it is possible that radioactive materials are discharged. -Currently, a large quantity of radioactive wastewater exists inside the turbine building of Fukushima Daiichi Nuclear Power Station. Particularly, wastewater in Unit 2 is highly radioactive. We have been planning to transfer such wastewater to the Centralized Radiation Waste Treatment Facility once measures to prevent leakage are implemented inside the facility buildings. After transfer to the Centralized Radiation Waste Treatment Facility, the wastewater will be stably stored. (Previously announced on April 15th, 2011) With this regard, on April 10th, we received direction from Minister of Economy, Trade and Industry to report on matters in connection with transfer of high level radioactive wastewater to the Centralized Radiation Waste Treatment Facility, such as necessity, assessment of safety, plans on permanent safety storage of wastewater and treatment facilities. Since we completed implementing measures to prevent leakage in the facility buildings, we have compiled the details based on the direction given and reported to Minister of Economy, Trade and Industry. The content of the report has been confirmed by Nuclear and Industrial Safety Agency. At 10:08 am on April 19th, based on the method described in the report, we started transferring high level radioactive wastewater to the Centralized Radiation Waste Treatment Facility. -From 2:30 pm to 3:45 pm on April 15th, we installed 3 sandbags containing zeolite (as an absorbent material) between the screen pump rooms of the Unit 3 and Unit 4. Also, from 9:00am to 11:15am, we threw in two sandbags between the screen pump rooms of Unit 1 and 2, and five sandbags between the screen pump rooms of Unit 2 and 3. -From 10:19 am to 5:00 pm on April 15th, we transferred distribution panels of the pumps to inject water to the reactors of Units 1 to 3 as a countermeasure against tsunami. -At 2:34pm on April 17th, power supplies to a common spent fuel pool was temporarily stopped because a breaker at the upstream side was released due to an electrical short circuit which was caused by an insufficient treatment of the end of the unused cable which was connected to the power source of the common spent fuel in parallel. However, after removal of the cable and checkups, at 5:30pm, the power supplies to the common spent fuel pool was restored. -From 11:30am to 2:00pm, we opened and closed the double doors and conducted surveys of the situation of the inside of the nuclear reactor building of Unit 3 and measured a dose of radiation, etc. by a remote control robot. Also, from 4:00pm to 5:30pm, we did the same kind of work on Unit 1. From 1:42pm to 2:33pm on April 18th, we opened and closed the double doors, measured a dose of radiation and so on, and conducted surveys of the situation of the inside of the nuclear reactor building of Unit 2, by a remote control robot. -From 11:50am to 1:05pm on April 18th, we suspended operations injecting water to the reactor of Unit 1 to 3, and replaced hoses for injecting water, to the brand new ones. -We will continue to take all measures to ensure the safety and to continue monitoring the surrounding environment around the power station.
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