Tepco Press Release (Apr 04,2011) Plant Status of Fukushima Daiichi Nuclear Power Station (as of 6:00 PM, April 4)

Press Release (Apr 04,2011) Plant Status of Fukushima Daiichi Nuclear Power Station (as of 6:00 PM, April 4)

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. -At approximately 10:50 am on March 24th, white fog-like steam arising from the roof part of the reactor building was observed. -We had been injecting seawater into the reactor, but from 3:37 pm on March 25th, we started injecting freshwater. -We had been injecting fresh water to the reactor using fire engines; however we switched over utilizing temporary electrical pump at 8:32 am on March 29th. -Some of turbine building lights were turned on April 2nd. -We injected fresh water to the reactor by a temporary motor driven pump, but, from 10:42am to 11:52am on April 3rd we temporarily switched the pump to the fire fighting pump to inject fresh water to use power through off-site transmission line. We're now injecting fresh water to the reactor by a motor driven pump powered by off-site transmission line. 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. -We have been injecting seawater into the reactor, but from 10:10 am on March 26th, we started injecting freshwater (with boric acid). -We had been injecting fresh water in to the reactor utilizing fire pump, however, we switched over to utilizing temporary electrical pump from 6:31 pm on March 27th. -Some of turbine building lights were turned on April 2nd. -We injected fresh water to the reactor by a temporary motor driven pump, but, from 10:22am to 0:06pm on April 3rd, we temporarily switched the pump to the fire fighting pump to inject fresh water to use power through off-site transmission line. We're now injecting fresh water to the reactor by a motor driven pump powered by off-site transmission line. Unit 3(Shut down) -Explosive sound and white smoke were confirmed at 11:01am March 14th. It was assumed to be hydrogen explosion. -We had been injecting seawater into the reactor pressure vessel, but from 6:02 pm on March 25th, we started injecting freshwater. -We had been injecting fresh water in to the reactor utilizing fire pump, however, we switched over to utilizing temporary electrical pump from 8:30 pm on March 28th. -Some of turbine building lights were turned on April 2nd. -We injected fresh water to the reactor by a temporary motor driven pump, but, from 10:03am to 0:16pm on April 3rd, we temporarily switched the pump to the fire fighting pump to inject fresh water to use power through off-site transmission line. We're now injecting fresh water to the reactor by a motor driven pump powered by off-site transmission line. Unit 4(outage due to regular inspection) -At approximately 6 am on March 15th, we confirmed the explosive sound and the sustained damage around the 5th floor rooftop area of the Nuclear Reactor Building. -Some of turbine building lights were turned on March 31st . -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 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 3:42PM, 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 -Water spray by the concrete pump truck to Unit 4 was conducted from 5:14 pm to 10:16 pm on April 3rd. -From 11:05 am to 1:37 pm on April 4th, fresh water injection by the temporarily electric pump to Unit 2 was conducted. -At 5:03 pm on April 4th, spray water by the concrete pumping vehicle to Unit 3 was initiated. -We are considering further spraying subject to the conditions of spent fuel pools. Draining water from underground floor of turbine buildings -In regard with transferring water from a condensate storage tank to a suppression pool water surge-tank in unit 1, the work began at 1:55 pm April 3rd. -Water transfer from a condenser to a condensate storage tank in unit 2, began at approximately 5:10 pm, April 2nd. Casualties -Presence of 2 TEPCO employees at the site is not confirmed on March 11th. -On March 24th, it was confirmed that 3 workers from cooperative companies who were in charge of cable laying work in the 1st floor and the underground floor of turbine building were exposed to the radiation dose of more than 170 mSv. 2 of them were confirmed that their skins on legs were contaminated. After they were decontaminated, since there was a possibility of beta ray burn injury, they were transferred to Fukushima Medical University Hospital. The third worker was also transferred to Fukushima Medical University Hospital on March 25th. Later, the 3 workers were transferred to National Institute of Radiological Sciences in Chiba Prefecture. They all left the hospital on March 28th. Regarding this event, TEPCO has reported to the related government ministries and agencies on measures to be taken to assure appropriate radiation dose control and radiation exposure related operations. We will inform the related parties of countermeasures and continue to take all possible measures to future management. 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) From now on, 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 10:37 am March 21st, water spraying to common spent fuel pool and finished at 3:30 pm (conducted by TEPCO). -At around 3:37 pm, March 24th, electricity supply to common spent fuel pool has started from external power source. At around 6:05 pm, fuel pool cooling pump was started to cool the pool. -We found no signs of abnormal situation for the casks by visual observation during the patrol activity. A detailed inspection is under preparation. -At Units 5 and 6, in order to prevent hydrogen gas from accumulating within the buildings, we have made three holes on the roof of the reactor building for each unit. -In total 12 fire engines are lent for the water spraying to the spent fuel pools and water injection to the nuclear reactors by various regional fire departments* as well as Tokyo Fire Department. Also, instruction regarding the setting and operation of large scale decontamination system was provided by Niigata City Fire Headquarter and Hamamatsu City Fire Headquarter. *:Koriyama Fire Department, Iwaki Fire Brigade Headquarters, Fire Headquarters of Sukagawa District Wide Area Fire-fighting Association, Yonezawa City Fire Headquarters, Utsunomiya City Fire Headquarters, Fire Headquarters of Aizu-Wakamatsu wide area municipal association, Saitama City Fire Bureau, and Niigata City Fire Bureau. -By March 22nd, Units 1 through 6 were started to be energized from the external power source. -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. -The second barge of the U.S. Forces with freshwater to be used to cool down the reactors etc. was towed by a ship of Maritime Self-Defense Force and came alongside the pier at 9:10 am on April 2nd. We began to replenish the filtrate tanks with water of a barge (the first barge) at around 10:20 am on April 2nd and continued until 4:40 pm. -We began to transfer fresh water from the second barge to the first barge on April 3rd at 9:52 am and continued until 11:15 am on April 3rd. -We also began to transfer the radioactive water we collected from the building of Radioactive Waste Treatment Facilities to the Unit 4 turbine building. On April 4th, water level of the pit in the trench of Unit 3 increased in 15cm. 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. -We also began to transfer the radioactive water we collected from the building of Radioactive Waste Treatment Facilities to the Unit 4 turbine building. -Today at around 9:30 am, we detected water containing radiation dose over 1,000 mSv/h in the pit* where supply cables are stored near the intake channel of Unit 2. Furthermore, there was a crack about 20 cm on the concrete lateral of the pit, from where the water in the pit was out flowing (previously announced). During the same day, we injected fresh concrete to the pit, but we could not observe a reduction in the amount of water spilling from the pit to the sea. Therefore, we considered that a new method of stopping the water and determined to use the polymer. Necessary equipment and experts of water shutoff will be dispatched to the site and after checking the condition, we're doing continuous work to stop water by injecting polymer (April 3rd). From 7:08 am to 7:11 am on April 4th, we put the tracer from the pit and began an investigation for flows of water. -Monitoring posts of No.1 - No.8 set up near the boundary of power station area have been restored. We will periodically monitor the data and announce the results of monitoring. -We will continue to take all measures to ensure the safety and to continue monitoring the surrounding environment around the Power Station.