Due to the Tohoku-Chihou-Taiheiyou-Oki Earthquake which occurred on March
11, 2011, TEPCO's facilities including our nuclear power stations have
been severely damaged. We deeply apologize for the anxiety and
inconvenience caused.
With regard to the accident at Fukushima Daiichi Nuclear Power Station, on
April 17, 2011, we have compiled the roadmap towards restoration from the
accident and on July 19 we accomplished the Step1 target "Radiation dose
is in steady decline". Then on December 16 we confirmed the accomplishment
of the Step 2 target "Release of radioactive materials is under control
and radiation doses are being significantly held down".
In addition, on December 21, 2011, we have compiled the "Mid-to-long-Term
Roadmap toward the Decommissioning of Fukushima Daiichi Nuclear Power
Units 1-4, TEPCO".
In addition to the maintenance of the plant's stable condition, we will
implement Mid-to-Long Term countermeasures towards the decommissioning of
Fukushima Daiichi Nuclear Power Units 1-4 to enable evacuees to return to
their homes as soon as possible and reduce the anxiety of the people in
Fukushima and the whole nation as soon as possible.
Below is the status of TEPCO's major facilities.
*The updates are underlined.
[Nuclear Power Station]
· Fukushima Daiichi Nuclear Power Station: Unit 1 to 3: shut down due to
the earthquake:
(Units 4 to 6: outage due to regular inspections before the earthquake)
- At 12:28 pm on February 6, 2012, at a group of concentrated water
storage tanks, a TEPCO employee found a leakage from on the tanks. As a
result of tightening a connecting volt of the tank, at 2:03 pm on the
same day, we confirmed stoppage of the leakage's bleed at the connecting
part. The leaked water originated from the concentrated water (salt
water) after being treated by the desalination equipment (reverse
osmosis membrane) and we evaluated a leakage amount of 0.6L. Currently,
as there still remains the bleed coming down from the connecting part on
the surface of the cement on which the tank is installed, we don't find
any water flowing into the gutter, and thus it will not flow out into
the ocean. (At 2:45 pm on the same day, we have piled sandbags just in
case). In the mean time, as a result of measuring the surface
radioactive rate at the cement basement right under the connecting part
that has the bleed, Gamma ray was 20mSv/h and Beta ray 250mSv/h.
- At 10:00 am on February 6, we started transfer of the accumulated water
at basement of turbine building of Unit 6 to the temporary tank. At 4:00
pm on the same day we stopped the transfer.
- Since February 2, as the tendency of temperature increase has grown, at
7:20 pm on February 3, 2012, we changed the injection amount into Unit 2
reactor through feed water system from approx. 2.9 m3/h to approx.
4.9 m3/h and changed that though reactor core spray system from approx.
5.8 m3/h to approx. 3.8 m3/h (which means setting them at those of
before flow adjustment on February 1, 2012). After that, we have
observed the tendency of temperature at the upper head of the bottom of
PCV. The temperature was around 70.0 °C (approx. 70.3 °C at 11:00 pm on
February 5) and in order to prevent further temperature increase, we
decided to increase the amount of water injected to the reactor. At 1:29
pm on February 6, the water injection volume to the Unit 2 reactor
through the feed water system was changed from approx. 5.8 m3/h to
approx. 6.8 m3/h (the water injection through the reactor core spray
system remains approx. 3.8 m3/h). At this moment, temperature indicates
approx. 71.0 °C (as of 11:00 am on February 6). As a result of the
sampling for the Gas Control System of the Unit 2 which we conducted on
the same day to make sure there is no re-criticality state, we confirmed
that the concentration of Xe-135 was below the detectible limit
(1.0 x 10-1 Bq/ cm3) at the system's entrance, meaning that it falls
below the re-criticality criteria, or 1 Bq/cm3. Continuing to monitor
the trend after that, as it was still showing a high value, from 0:19 am
to 3:20 am on February 7 we injected boric acid into the reactor as a
safety countermeasures against the re-criticality, and on 4:24 am we
changed the amount of the core spray system injection water from 3.7m3/h
to 6.7m3/h* (the amount of the continuing feed water system injection is
6.8m3/h). Currently, the temperature is 72.2°C (as of 5 am on February
7). We will monitor the progress continuously.
*In the Chapter 12 of Nuclear Reactor Facilities Security Regulation "The
Way of Ensuring Mid-term Security", as the treatments like "Operational
limitation" or "Measures required in case of not satisfying the
operational limitation" are determined, it is supposed the operator act
per the required measures if it fails to satisfy the operational
limitation. This time, to implement maintenance works, we changed the
amount of water injection into Unit 2 (from 3:48 am on February 7) by
conducting a planned shift beyond the range of operational limitation.
- As finding of accumulated water containing radioactive materials at the
trench between the Process Main Building and the Miscellaneous Solid
Waste Volume Reduction Treatment Building [High Temperature Incinerator
Building] (December 18, 2011), we started the inspection of other
trenches at the site on January 11.
As a result of the inspection made on February 6, the preliminary
results of the nuclide analysis and executed place are as follows:
· Inside the Unit 6 off-gas plumbing duct
I-131: below the detectible limit, Cs-134: 1.2 x 10-1 Bq/ cm3,
Cs-137: 1.9 x 10-1 Bq/ cm3
· Inside the Unit 5 pump room circulating water pump valve disorption pit
I-131: below the detectible limit, Cs-134: 1.0X10-1 Bq/ cm3,
Cs-137: 1.6 x 10-1 Bq/ cm3
· Inside the Unit 6 pump room circulating water pump valve disorption pit
I-131: below the detectible limit, Cs-134: 1.1 x 10-1 Bq/ cm3,
Cs-137: 1.4 x 10-1 Bq/ cm3
· Inside the Unit 5 off-gas duct and heavy oil plumbing trench (the
southwest side of Unit 5), we confirmed there is no puddle water
· Fukushima Daini Nuclear Power Station:
(Units 1 to 4: shutdown due to the earthquake)
· Kashiwazaki Kariwa Nuclear Power Station: Units 6: under normal operation
(Units 1 to 5 and 7: outage due to regular inspections)
[Thermal Power Station]
· Power supply has returned to normal and the facilities damaged by the
earthquake are now being handled in a timely manner.
[Hydro Power Station]
· Power supply has returned to normal and the facilities damaged by the
earthquake are now being handled in a timely manner.
[Impacts on Transmission Facilities]
· Power supply has returned to normal and the facilities damaged by the
earthquake are now being handled in a timely manner.
[Impacts on Power Supply and Demand Balance]
This winter, there are some minus factors such as the regular inspection
of Unit 5 at Kashiwazaki-Kariwa Nuclear Power Station. On the other hand,
there are several plus factors such as the recovery of the common thermal
power stations which suffered the earthquake. As a result, we expect to
secure 53.7 GW (at the end of February) supply power.
Compared to the maximum demand in the last winter, which is 51.5 GW, we
will have 2.2 GW generation reserve margin.
We expect to maintain stable power supply this winter, however, as there
remains possibilities of unplanned shutdowns at our power stations and
growth in the demand according to the rapid change in the temperature, we
would like to ask your reasonable effort to save electricity.
We will continue to make our efforts to maintain stable operation and
maintenance of the power facilities in order to "prevent in principle" the
planned blackouts and secure power supply.
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Appendix: Past Progress (As of 10:00 am, February 7, 2012) (PDF 406KB)
Appendix: Past Progress (From March 11, 2011 to July 31, 2011) (PDF 225KB)
* Revised past progress