Print

Language



Corporate Information

 
Press Release (Apr 07,2011)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 7:00 pm, April 7)
*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.
-We had been injecting seawater into the reactor, but from 3:37 pm on
 March 25th, we started injecting freshwater.
-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.
-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. 
-We have been injecting seawater into the reactor, but from 10:10 am on
 March 26th, we started injecting freshwater (with boric acid).
-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.
-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 
-From 6:53am to 8:53am on April 7th, spraying water to Unit 3 by the
 concrete pump vehicle was conducted. 
-From 1:29 pm to 2:34 pm, April 7th, freshwater injection to Unit 2 by a 
 temporary motor-driven pump was conducted. 
-From 6:23am, April 7th, spraying water to Unit 4 by the concrete pump 
 vehicle was conducted.  
-We will conduct further water spray depending on the conditions of spent
 fuel pools. 
Draining water from underground floor of turbine buildings 
-At 1:55 pm April 3rd, in Unit 1, water transfer from a condensate storage
 tank to a suppression pool water surge-tank was initiated.
-At 5:10 pm, April 2nd, in Unit 2, water transfer from a condensate
 storage tank was to a suppression pool water surge-tank was initiated. 
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.
-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 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.
-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.
-As a countermeasure against outflow of radioactive water into the sea
 near the cooling water intake at unit 2 of Fukushima Daiichi Nuclear
 Power Station, we have injected coagulant into the pit from April 5th and
 we have observed stoppage of spilling of water from the crack on the
 concrete lateral of the pit at 5:38 am, April 6th.
-Continued work from yesterday, we have put 6,000 litters of coagulant
 into the breakage and surrounding ground after investigation of the
 leakage route by putting tracer into the 9 holes drilled around
 electrical conduit and the pit. As at 9:30 am, we have been observing
 there is no leakage of water into the sea from the pit..
-For the sake of completeness, we put further reinforcement for the
 stoppage of leakage and consider countermeasure including continuous
 injection of coagulant. We will also note the water level of turbine
 building of unit 2 remain unchanged. We will further investigate if there
 is any other leakage.
                                       (Previously announced on April 6th)
 On April 6th, we installed rubber boards as a countermeasure against
 outflow from the intake. We will further investigate if there is any
 other leakage.
-There is plenty of radioactive wastewater in the turbine buildings.
 Especially, Unit 2's wastewater is very highly radioactive. To store this
 stably, it was decided that this needed to be transferred to the Central
 Radioactive Waste Disposal Facility. However, within that facility, we
 are storing ten thousand tons of low level radioactive wastewater. In
 order to transfer more wastewater, we need to discharge the low level
 radioactive wastewater. In addition, as low radioactive subsurface water
 is piling up in sub-drain pits of Units 5 and 6 and a part of subsurface
 water is running into buildings. We are concerned that important
 equipment to secure the safety of reactors may be submerged. Based on the
 Section 1 of the Article 64 of the Nuclear Reactor Regulation Law, we
 have decided to discharge to the sea approximately ten thousand tons of
 the accumulated low level radioactive water and a total of fifteen
 hundred tons of the low level radioactive subsurface water stored in the
 sub drain pits of Unit 5 and 6 as soon as we get ready.
-We evaluate the impact on the discharge of the low radioactive wastewater
 to the sea as approximately 0.6 mSv per year per an adult if an adult
 eats adjacent fish and seaweeds everyday. The amount (0.6 mSv of
 effective radioactive doses per year) is one-forth of annual radioactive
 dose to which the general public is exposed from nature.
                                       (Previously announced on April 4th)
-At 7:03 pm, April 4th, discharge of low radioactive wastewater
 (approximately 10,000 ton in total) from Central Radioactive Waste
 Disposal Facility to the sea was initiated. 
-At 9:00 pm, April 4th, discharge of low radioactive subsurface water
 (1,500 ton in total) from sub-drain pits of Units 5 and 6 to the sea was
 initiated.
-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.
-At 2:33 pm, April 7th, one of the workers in charge of stuffing sandbags 
 at the soil disposal situated at the northern part of the site became ill 
 and was brought to J-Village. After we confirmed that he was not 
 contaminated, he was brought to Iwaki City Kyoritsu Hospital by an 
 ambulance. 
-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