* The updates from the previous press release 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 a
big quake occurred at 3:36 pm on March 12, 2011. It was
assumed to be hydrogen explosion.
- At 3:37 pm on March 25, 2011, we started injecting
freshwater to the reactor and are now injecting fresh water
by a motor driven pump powered by the off-site transmission
line.
- At 10:11 am on December 10, 2011, in addition to water
injection from water feeding system, we started water
injection from piping of core spray system to the
reactor.
The current amount of water injection from the feed water
system is approx. 4.8 m3/h and that from the reactor core
spray system is approx. 2 m3/h.
- At 1:31 am on April 7, 2011, we commenced injection of
nitrogen gas into Primary Containment Vessel.
- At 11:22 am on August 10, 2011, we started cyclic cooling
for the water in the spent fuel pool by an alternative
cooling equipment of the Fuel Pool Cooling and Filtering
System.
- At 4:04 pm on November 30, 2011, we started operation to
inject nitrogen into the reactor pressure vessel.
- At 6:00 pm on December 19, 2011, a full-scale operation
of the PCV gas management system started.
Unit 2 (Shut down)
- At approximately 6:00 am on March 15, 2011, an abnormal
noise began emanating from nearby Pressure Suppression
Chamber and the pressure within the chamber decreased.
- At 10:10 am on March 26, 2011, we started injecting
freshwater to the reactor and are now injecting fresh water
by a motor driven pump powered by the off-site transmission
line.
- At 2:59 pm on September 14, 2011, in addition to water
injection from feed water system, we started water
injection from piping of core spray system to the
reactor.
The current water injection amount from the reactor feed
water system is approx. 2.7 m3/h and that from the core
spray system is approx. 6m3/h.
- At 5:21 pm on May 31, 2011, we started cyclic cooling for
the water in the spent fuel pool by an alternative cooling
equipment of the Fuel Pool Cooling and Filtering
System.
- At 8:06 pm on June 28, 2011, we started injecting
nitrogen gas into the Primary Containment Vessel.
- At 6:00 pm on October 28, 2011, a full operation of the
PCV gas control system started.
- From 9:40 am to 12:30 pm on March 26, the water level and
water temperature inside the PCV of Unit 2 was investigated
with the industrial endoscope. As a result, the water level
was confirmed to be 60 cm from the bottom of the PCV and
the water temperature was confirmed to be in the range of
approx. 48.5 °C to 50.0 °C. From 9:30 am to 10:30 am on
March 27, we measured ambient dose rates of inside of PCV
by inserting a dose rate meter around the upper part of
grating through one of the penetration points of PCV (X-53
Pene). We confirmed that an ambient dose rate was 31.1 to
48.0 Sv/h at the point of approx. 50 cm inside from the
edge of the penetration point (PCV side) towards the
center. Another was 39.0 to 72.9 Sv/h at the point of
approx. 1m inside from the edge towards the center.
- At 10:46 am on December 1, 2011, we started the nitrogen
injection to the Reactor Pressure Vessel.
- At 11:50 am on January 19, 2012, we started the operation
of the spent fuel pool desalting facility.
Unit 3 (Shut down)
- Explosive sound and white smoke were confirmed at
approximately 11:01 am on March 14, 2011. It was assumed to
be hydrogen explosion.
- At 6:02 pm on March 25, 2011, we started injecting fresh
water to the reactor and are now injecting fresh water by a
motor driven pump powered by the off-site transmission
line.
- At 2:58 pm on September 1, 2011, we started water
injection by core spray system in addition to water
injection by the reactor feed water system piping
arrangement.
The current water injection amount from the reactor feed
water system is approx 1.8m3/h and that from the core spray
system is approx. 4.9m3/h.
- At 7:47 pm on June 30, 2011, we started cyclic cooling
for the water in the spent fuel pool by an alternative
cooling equipment of the Fuel Pool Cooling and Filtering
System.
- At 8:01 pm on July 14, 2011, injection of nitrogen gas
into the Primary Containment Vessel started.
- At 4:26 pm on November 30, 2011, we started operation to
inject nitrogen into the reactor pressure vessel.
- At 7:00 pm on March 14, 2012, the regular operation of
the PCV gas control system started.
Unit 4 (Outage due to regular inspection)
- At around 6 am on March 15, 2011, we confirmed an
explosive sound and the sustained damage around the 5th
floor rooftop area of Reactor Building.
- At 12:44 pm on July 31, 2011, we started cyclic cooling
for the water in the spent fuel pool by an alternative
cooling equipment of the Fuel Pool Cooling and Filtering
System.
- From 2:00 pm to 4:40 pm on March 27, Hydrazine injection
into the Unit 4 reactor well through the instrument pipes
inside the reactor was conducted.
- At 10:58 am on November 29, 2011, in order to decrease
more salinity, we installed Ion exchange equipment and
started the operation of such equipment.
- At 5:41 am on March 27, the cooling of the spent fuel
pool of Unit 4 was stopped (water temperature at the time
of stoppage: approx. 24 °C) in order to implement the
replacement of flexible hose in the primary coolant system
and pump inlet strainer in the secondary coolant system.
Stoppage is scheduled to continue till March 28. The
increasing rate of the water temperature is estimated to be
approx. 0.5 °C/h, therefore no material issue in the
management of the pool temperature is expected.
- At this moment, we don't think there is any reactor
coolant leakage inside the primary containment vessel.
Unit 5 (Outage due to regular inspection)
- Sufficient level of reactor coolant to ensure safety is
maintained.
- At 5:00 am on March 19, 2011, we started the Residual
Heat Removal System Pump in order to cool the spent fuel
pool.
- At 2:45 pm on July 15, 2011, we started the operation of
the original Residual Heat Removal System (System B) by its
original seawater pump.
- At 10:11 am on December 22, 2011, since we finished the
recovery work of seawater pump (System B) of equipment
water cooling system, we made a trial run. At 11:25 am on
the same day, we confirmed no abnormalities and restarted
the operation.
- At 7:05 am on March 28, 2012, we stopped Shutdown Cooling
System due to suspension of power supply for construction
work regarding power supply cars installation in case of
outage of AC power source of Unit 5 and 6. Due to this
work, cooling the reactor stopped (water temperature of the
reactor when sftopped: approx. 32.3°C). At 2:56 pm on the
same day, we restarted Shutdown Cooling System and
re-started cooling the reactor. (water temperature of the
reactor when restarted: approx. 38.2°C)
Unit 6 (Outage due to regular inspection)
- Sufficient level of reactor coolant to ensure safety is
maintained.
- At 10:14 pm on March 19, 2011, we started the Residual
Heat Removal System Pump of Unit 6 to cool down Spent Fuel
Pool.
- At 2:33 pm on September 15, 2011, we started separately
cooling the reactor through the Residual Heat Removal
System and the spent fuel pool through Equipment Cooling
Water System and Fuel Pool Cooling System.
Others
- At around 10:00 am on June 13, 2011, we started the
operation of the circulating seawater purification facility
installed at the screen area of Unit 2 and 3.
- At 8:00 pm on June 17, 2011, we started operation of
Water Treatment Facility against the accumulated water. At
6:00 pm on July 2, we started the circulating injection
cooling to inject the water, which was treated by the
accumulated water treatment system, to the reactors through
the buffer tank.
- At 7:41 pm on August 19, 2011, we started treatment of
accumulated water by parallel operation of one line from
the cesium adsorption instrument to the decontamination
instrument and the other treatment line of the cesium
adsorption instrument No.2.
- At 2:06 pm on October 7, 2011, we started to spray
purified accumulated water brought from Unit 5 and 6
continually in order to prevent dust scattering and
potential fire outbreaks from the cut down trees.
- On October 28, 2011, we started installation of the water
proof wall at the sea side, in front of the existing shore
protection, Units 1-4, in order to contain marine pollution
by underground water.
- At 12:25 pm on December 13, 2011, we started the
re-circulating operation of desalination facility (reverse
osmosis membrane) for the purpose of suppression of
condensed water after desalination treatment.
- At around 8:30 on March 26, 2012, in the area of
condensed water tanks for water desalinations (reverse
osmosis membrane) of Fukushima Daiichi Nuclear Power
Station, a partner company worker found that water was
leaked from a pipeline (anti-pressure hose) which
transferred the condensed water from the water
desalinations to the condensed water tanks. In order to
stop the water leakage, we stopped the transfer pumps of
the water desalinations (reverse osmosis membrane) and then
the leakage stopped. After that, we closed the valves at
the both sides to the leakage point of the pipeline
(anti-pressure hose). When we checked the leakage on the
site later, we found that a part of the leaked water had
been poured into a nearby drainage for general draining
water. And then, we conducted sampling surveys on the
leaked water, the water which was poured into the drainage,
and the seawater around the exit of the drainage. As a
result, we judged that some water including radioactive
materials was poured into the sea from the exit of the
drainage located at about 300 m south from the discharge
channel of Unit 1-4 of Fukushima Daiichi Nuclear Power
Station. At this moment, the water desalinations (reverse
osmosis membrane and evaporative concentration apparatus)
are not in service. However, because we have much treated
fresh water, it does not affect water injection to the
reactors. Total amount of leaked water is estimated to be
approx 120 m3 in accordance with the operation hour of the
pump. Approx. 80 L out of 120 m3 is estimated to flow into
the sea at maximum. Thereafter, the cesium adsorption
apparatus was stopped at 5:00 pm and the second cesium
adsorption apparatus was stopped at 5:29 pm.
At 9:10 am on March 28, 2012, we restarted the 2nd Cesium
Adsorption Apparatus after having completed the work
against the leakage and it reached to the rated flow
(approx 40 m3/h) at 9:20 am on the same day. At the 12:07
pm and 12:13 pm on the same day, we restarted the two lines
of the desalination facility (reverse osmosis membrane). As
for the Cesium Adsorption Apparatus, power retrofitting
work had been conducted in order to establish 2 lines of
power sources for accumulated water treatment facility.
Thus, after having completed the work, at 2:32 pm on the
same day, we restarted the Cesium Adsorption Apparatus and
it reached the rated flow (approx. 19.1 m3/h).
- From 10:00 am to 4:00 pm on March 27, we transferred
accumulated water from the basement of Unit 6 T/B to the
temporary tank. At 10:00 am on March 28, we restarted the
transfer.
distributed by | This press release was issued by TEPCO - Tokyo Electric Power Company Inc. and was initially posted at http://www.tepco.co.jp/en/press/corp-com/release/2012/12032802-e.html . It was distributed, unedited and unaltered, by noodls on 2012-03-28 14:51:48 PM. The issuer is solely responsible for the accuracy of the information contained therein. |