*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 Mar 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.
-At approximately 11:30 am on March 24th, lights in the main control room
was restored.
-We had been injecting seawater into the reactor, but from 3:37 pm on
March 25th, we started injecting freshwater.
-At 8:20 am on March 29th, we switched injection of fresh water from using
fire engine to temporary electrical pump.
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.
-At 6:20 pm on March 21st, white smoke was confirmed arising from the top
of the reactor building. As of 7:11 am on March 22nd, smoke decreased to
the level to nearly non-existent.
-We have been injecting seawater into the reactor, but from 10:10 am on
March 26th, we started injecting fresh water (with boric acid).
-At approximately 4:46 pm on March 26th, the light in the main control
room was restored.
-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.
Unit 3(Shut down)
-Explosive sound and white smoke were confirmed at 11:01am March 4th. It
was assumed to be hydrogen explosion.
-At 8:30am on March 16th, fog like steam was confirmed arising from the
reactor building.
-At approximately 6:15 am on March 17th the pressure of the Suppression
Chamber has temporarily increased. We were preparing to implement
measures to reduce the pressure of the reactor containment vessel
(partial discharge of air containing radioactive material to outside) in
order to fully secure safety. However, at present, it is not a situation
to immediately implement measures and discharge air containing
radioactive material to outside. We will continue to monitor the status
of the pressure of the reactor containment vessel.
-At approximately 4:00 pm, March 21st, light gray smoke was confirmed
arising from the floor roof of the Unit 3 building. On March 22nd, the
color of smoke changed to somewhat white and it is slowly dissipating.
-At approximately 10:45 pm on March 22nd, the light in the main control
room was turned on.
-At around 4:20 pm on March 23rd, our staff confirmed light black smoke
belching from the Unit 3 building. At approximately 11:30 pm on March
23rd and 4:50 am on March 24th, our employee found no signs of smoke.
-We had been injecting sea water 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.
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.
-On March 15th and 16th, we respectively confirmed the outbreak of fire at
the 4th floor of the northwestern part of the Nuclear Reactor Building.
We immediately reported this matter to the fire department and the
related authorities. TEPCO employees confirmed that each fire had already
died down by itself.
-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.
-We completed the repair work on the emergency diesel generator (A).
-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.
Today's work for cooling the spent fuel pools
-We are considering further spraying subject to the conditions of spent fuel
pools.
Casualty
-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 3:30PM, March 27th, we found that there was water in the trenches of
Units 1 to 3. The radioactive emission at the surface of the water was
0.4mSv/h for Unit 1 and over 1,000mSv/h for Unit 2. As for Unit 3, we
couldn't have access to the surface because of debris. We will continue
to monitor water in the trenches.
-We will continue to take all measures to ensure the safety and to
continue monitoring the surrounding environment around the Power Station.
