search



Corporate Information

 
Press Release (Apr 12,2011)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 7:00 pm, April 12)
  
*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. 
 
Unit 3(Shut down) 
-Explosive sound and white smoke were confirmed at approximately 11:01am 
 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, March 19th, we started the Residual Heat Removal System Pump 
 (C) in order to cool the spent fuel pool. 
-At 2:30 pm, 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, 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, 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, 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 4:26 pm to 5:16 pm on April 12th, we conducted water spraying to 
 Unit 3 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. 
-At around 11:35 am April 1st, a worker fell into the sea when he got 
 into a barge of the U.S. Forces to repair a hose of the ship. The worker 
 was rescued immediately, and was not injured and not contaminated. The 
 worker will be checked using the whole-body counter to ensure his health. 
-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, April 4, 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, 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. 
-Below is the status of TEPCO's major facilities due to the 7.1 magnitude 
 earthquake centered in the Fukushima-Hama-dori earthquake which occurred 
 at approximately 5:16 pm, April 11th 2011. Due to the shutdown of the 
 off-site power, water injection to the reactor of the units 1-3 was 
 suspended and was resumed at approximately 6:04 pm after restoration of 
 off-site power. No abnormalities were detected in the parameter of each 
 of the Units. Nitrogen gas injection to the reactor containment vessel 
 of Unit 1 was suspended and resumed at 11:34 pm. In addition, we 
 confirmed that the water level of Units 1-3's pit did not change 
 significantly and there were no injured workers inside of the buildings. 
-In regard to the earthquake occurred at 2:07 pm on April 12th with a 
 magnitude of 6.3, epicenter in the Fukushima-Hama-dori, no trouble were 
 detected in the plant units after the earthquake. Safety of workers has 
 also been confirmed. 
-At approximately 6:38 am, April 12th, a fire broke out at the distribution 
 switchboard containing batteries located in the sampling equipment 
 switchbox situated close to the south water discharge channel for Units 
 1-4. The self defense fire fighting team began extinguishing this fire 
 soon after it broke out. At approximately 6:45 am, this incident was 
 reported to the Futaba fire authorities. The Futaba fire authorities 
 confirmed the fire was extinguished as a result of site survey as of 
 9:12 am. This incident did not impact the external release of radioactive 
 substances and the cooling capability of the reactor. The data taken from 
 the monitoring of the environment in the area did not change. 
-Today, in order to confirm the conditions of the fuels stored in the 
 spent fuel pool of Unit 4, we sampled the water in the spent fuel pool. 
 We will be conducting nuclide analysis on these samples. 
-We will continue to take all measures to ensure the safety and to 
 continue monitoring the surrounding environment around the Power Station. 
back to page top


to TOP