TEPCO April 19th UPDATE
Plant Status of Fukushima Daiichi Nuclear Power Station
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 quakeoccurred at 3:36 pm on March 12th. It was assumed to be hydrogenexplosion.-At approximately 2:30 am on March 23rd, seawater injection to the nuclearreactor through the feed water system was initiated.-From 3:37 pm on March 25th, we started injecting freshwater and are nowinjecting fresh water by a motor driven pump powered by the off-sitetransmission line.-As it is suspected that hydrogen gas is accumulated inside reactorcontainment vessel, we commenced the valve opening operation concerninginjection of nitrogen gas into the reactor container vessel at 10:30 pmApril 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 emanatingfrom nearby Pressure Suppression Chamber and the pressure within thechamber decreased. -From 10:10 am on March 26th, we started injecting freshwater to thereactor and are now injecting fresh water by a motor driven pump poweredby the off-site transmission line.-From 7:35 pm on April 12th, we started transferring the high levelradioactive accumulated water in the trench of the turbine building tothe condenser by an underwater pump. At 5:04pm on April 13th, thescheduled transfer was completed. Unit 3(Shut down)-Explosive sound and white smoke were confirmed at approximately 11:01amon March 14th. It was assumed to be hydrogen explosion.-From 6:02 pm on March 25th, we started injecting fresh water to thereactor and are now injecting fresh water by a motor driven pump poweredby the off-site transmission line.Unit 4(outage due to regular inspection)-At approximately 6:00 am on March 15th, we confirmed the explosive soundand the sustained damage around the 5th floor rooftop area of the NuclearReactor Building.-At this moment, we do not consider any reactor coolant leakage inside thereactor 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 SystemPump (C) in order to cool the spent fuel pool.-At 2:30 pm on March 20th, the reactor achieved reactor cold shutdown. Ataround 5:24 pm on March 23rd, when we switched the temporary ResidualHeat Removal System Seawater Pump, it has stopped automatically. Ataround 4:14 pm on March 24th we replaced the pump, and restarted coolingof reactor at around 4:35 pm.-At this moment, we do not consider any reactor coolant leakage inside thereactor 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 SystemPump (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 RemovalSystem, we switched the power source from temporary to permanent at 3:38pm and 3:42 pm, Mar 25 respectively.-At this moment, we do not consider any reactor coolant leakage inside thereactor 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 4by a concrete pump vehicle.-We will conduct further water spray depending on the conditions of spentfuel pools, if needed.Others-The national government has instructed evacuation for those localresidents within 20km radius of the periphery and shelter in place forthose residents from 20km to 30km radius of the periphery, because it ispossible that radioactive materials are discharged.-Currently, a large quantity of radioactive wastewater exists inside theturbine 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 CentralizedRadiation Waste Treatment Facility once measures to prevent leakage areimplemented inside the facility buildings. After transfer to theCentralized Radiation Waste Treatment Facility, the wastewater will bestably stored. (Previously announced on April 15th, 2011)With this regard, on April 10th, we received direction from Minister ofEconomy, Trade and Industry to report on matters in connection withtransfer of high level radioactive wastewater to the CentralizedRadiation Waste Treatment Facility, such as necessity, assessment ofsafety, plans on permanent safety storage of wastewater and treatmentfacilities.Since we completed implementing measures to prevent leakage in thefacility buildings, we have compiled the details based on the directiongiven and reported to Minister of Economy, Trade and Industry. Thecontent of the report has been confirmed by Nuclear and Industrial SafetyAgency.At 10:08 am on April 19th, based on the method described in the report,we started transferring high level radioactive wastewater to theCentralized Radiation Waste Treatment Facility.-From 2:30 pm to 3:45 pm on April 15th, we installed 3 sandbags containingzeolite (as an absorbent material) between the screen pump rooms of theUnit 3 and Unit 4.Also, from 9:00am to 11:15am, we threw in two sandbags between the screenpump rooms of Unit 1 and 2, and five sandbags between the screen pumprooms of Unit 2 and 3.-From 10:19 am to 5:00 pm on April 15th, we transferred distributionpanels of the pumps to inject water to the reactors of Units 1 to 3 as acountermeasure against tsunami.-At 2:34pm on April 17th, power supplies to a common spent fuel pool wastemporarily stopped because a breaker at the upstream side was releaseddue to an electrical short circuit which was caused by an insufficienttreatment of the end of the unused cable which was connected to the powersource of the common spent fuel in parallel. However, after removal ofthe cable and checkups, at 5:30pm, the power supplies to the common spentfuel pool was restored.-From 11:30am to 2:00pm, we opened and closed the double doors andconducted surveys of the situation of the inside of the nuclear reactorbuilding of Unit 3 and measured a dose of radiation, etc. by a remotecontrol robot. Also, from 4:00pm to 5:30pm, we did the same kind of workon Unit 1. From 1:42pm to 2:33pm on April 18th, we opened and closed thedouble doors, measured a dose of radiation and so on, and conductedsurveys of the situation of the inside of the nuclear reactor building ofUnit 2, by a remote control robot.-From 11:50am to 1:05pm on April 18th, we suspended operations injectingwater to the reactor of Unit 1 to 3, and replaced hoses for injectingwater, to the brand new ones.-We will continue to take all measures to ensure the safety and tocontinue monitoring the surrounding environment around the power station.