*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.
- 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.
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 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.
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 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 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.
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
- Water spraying by the concrete pump truck to Unit 4 was conducted from
8:28 am to 2:14 pm.
- From 2:56 pm April 1st, freshwater injection to Unit 2 was conducted
by a temporary motor driven pump, and finished at 5:05 PM on the same
day.
- 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, work began at 0:00 pm
March 31st.
- In regard with transferring water from a condensate storage tank to a
suppression pool water surge-tank in unit 2 from 4:45 pm March 29th to
11:50 am, April 1st.
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 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.
- On March 28th, a puddle of water was found at a centralized
environmental facility process main building. As a result of a
radioactivity analysis, on March 29th, we detected approximately
1.2 x 10Bq/cm3 in a full dose at a radiation controlled area and
2.2 x 10Bq/cm3 in a full dose at a non-controlled area.
- At 12:03 pm, March 29th, when taking off the flange of the pipe of the
seawater piping of the Residual Heat Removal System, 3 workers from our
subcontractor were soaked with water in the pipe. After wiping the
water off, we confirmed that there was no radioactive contamination to
their bodies.
- At 12:21 pm, March 31st, campaigner's sound truck (1 driver) tried to
enter the site form the site's main gate, however it left after it was
blocked to enter. We reported this incident to Fukushima Prefectural
Police Department.
- A barge of the U.S. Forces with freshwater to be used to cool down
reactors etc. was towed by a ship of Maritime Self-Defense Force and at
3:42 pm on March 31st 2011, came alongside the pier. We began to
replenish the water with filtrate tanks at around 3:58 pm April 1st.
- 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.
- 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.
