Press Release (Apr 15,2011) Plant Status of Fukushima Daiichi Nuclear Power Station (as of 6:00 pm, April 15)

Press Release (Apr 15,2011) Plant Status of Fukushima Daiichi Nuclear Power Station (as of 6:00 pm, April 15)

*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. -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. -At this moment, we do not consider any reactor coolant leakage inside the reactor happened. Operation for cooling the spent fuel pools -From 2:08PM, April 15th, we began spraying water to Unit 4 by the concrete pumping vehicle. -We will conduct further water spray depending on the conditions of spent fuel pools, if needed. Others -We measured radioactive materials (iodine etc.) inside of the nuclear power station area (outdoor) by monitoring car and confirmed that radioactive materials level is getting higher than ordinary level. As listed below, we have determined that specific incidents stipulated in article 15, clause 1 of Act on Special Measures Concerning Nuclear Emergency Preparedness (Abnormal increase in radiation dose measured at site boundary) have occurred. ·Determined at 4:17 pm Mar 12th (Around Monitoring Post 4 ) ·Determined at 8:56 am Mar 13th (Around Monitoring Post 4 ) ·Determined at 2:15 pm Mar 13th (Around Monitoring Post 4 ) ·Determined at 3:50 am Mar 14th (Around Monitoring Post 6 ) ·Determined at 4:15 am Mar 14th (Around Monitoring Post 2 ) ·Determined at 9:27 am Mar 14th (Around Monitoring Post 3 ) ·Determined at 9:37 pm Mar 14th (Around main entrance ) ·Determined at 6:51 am Mar 15th (Around main entrance ) ·Determined at 8:11 am Mar 15th (Around main entrance ) ·Determined at 4:17 pm Mar 15th (Around main entrance ) ·Determined at 11:05 pm Mar 15th (Around main entrance ) ·Determined at 8:58 am Mar 19th (Around MP5) Hereafter, if the measured figure fluctuates and goes above and below 500 micro Sv/h, we deem that as the continuous same event and will not regard that as a new specific incidents stipulated in article 15, clause 1 of the Act on Special Measures Concerning Nuclear Emergency Preparedness (Abnormal increase in radiation dose measured at site boundary) has occurred. In the interim, if we measure a manifestly abnormal figure and it is evident that the event is not the continuous same event, we will determine and notify. -The national government has instructed evacuation for those local residents within 20km radius of the periphery and evacuation to inside for those residents from 20km to 30km radius of the periphery, because it is possible that radioactive materials are discharged. -From April 2nd, we began to transfer the radioactive water we collected from the Central Environmental Facility to the Unit 4 turbine building. On April 4th, water level of the pit in the trench of Unit 3 increased by 15cm from previous day. Pathway of water flow is unknown. We can not deny the possibility that water in the turbine building of Unit 4 flows into the trench of Unit 3. So, we stopped transferring water to the Unit 4 turbine building to make assurance. Present water level of the pit in the trench of Unit 3 is not changed from the time we stopped transferring, and is being stable. -From 7:03 pm on April 4th, we started to discharge to the sea approximately ten thousand tons of the accumulated low level radioactive water in the Central Radioactive Waste Disposal Facility. We are confirming the amount of discharged water. From 9:00 pm on April 4, we conducted discharging a total of 1,500 tons of the low level radioactive subsurface water stored in the sub drain pits of Unit 5 and 6. The amount of discharged water was approximately 1,323 tons. -From 3:00 pm to 4:30 pm, April 5th, in order to prevent diffusion of radioactive contaminated water out from the site port facility to breakwater area which is south to the power station, we began repair of breakwater by founding the large sandbag around it to replace damaged steel water bar. We will continue the operation to prevent diffusion. From 8:45 am to 10:45 am on April 11, in order to prevent water containing radioactive material from spilling from a plant's port to the sea, we conducted works to install 120m wide double silt fences around a breakwater on the south of the station. From 8:45 am to 1:50 pm on April 13, we installed silt fences (double layered) in front of Unit 3 and 4 screens, and from 7:45 am to 0:20 pm on April 14 we also installed the same in front of Unit 1 and 2 screens, and around the north of south breakwater. -We took a sample from Unit 4 spent fuel pool on 12th April, in order to understand the fuel condition stored within the spent fuel pool. We are planning to conduct a nuclide analysis. -From 8:02 to 9:55 am on April 15th, an unmanned helicopter was flown over Unit 1 to 4, in order to check the condition of the reactor buildings. -We will continue to take all measures to ensure the safety and to continue monitoring the surrounding environment around the Power Station.