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.
* 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)
* With regard to the water injection volume for Unit 2 reactor, which was
increased with temperature figure raising, we have gradually adjusted it
to the original volume before temperature increasing (Feed water system:
approx. 3.0m3/h, core spray system: approx. 6.0m3/h). During our
observing the plant parameter after the decreasing the flow rate of feed
water system on February 22, we found that one thermometer in the lower
part of the RPV indicated the different movement from others. From 0:21
pm to 2:48 pm on February 23, we investigated the concerned device. As
the result of the measurement of DC resistance, we found no breaking
wire and availability of the thermometer. But we confirmed that the DC
resistance of it became higher than the previous measurement test data.
We will evaluate the soundness of the concerned device and examine
correspondence in future. We make sure no re-criticality state because
there were no significant changes at the monitoring post and as the
result of the sampling for the Gas Control System of the Unit 2, we
confirmed that the concentration of Xe-135 was below the detectible
limit.
· At 5:00 am on February 24, the temperature of the lower part of the
RPV (top of the lower head)(135°) : approx. 48.9 °C (approx. 41.7°C
at 5:00 am on February 23)
(Reference)
· At 5:00 am on February 24, the temperature of the lower part of the
RPV (top of the lower head)(270°) : approx. 38.1 °C (approx. 35.9°C
at 5:00 am on February 23)
- At 3:11 pm on February 23, in the alternative cooling system of the
spent fuel pool of Unit 4, as the inhale pressure of the primary
circulating pump showed the tendency of decrease, we stopped the pump in
order to conduct flushing of the strainer on its entry side and
suspended cooling of the spent fuel pool (the temperature of the pool at
the time of the suspension was approx. 25°C) After the flushing, at 5:18
pm on the same day we resumed the pump and cooling of the spent fuel
pool of Unit 4. (the temperature of the pool at the time of the resuming
was approx. 26°C)
- At 6:00 am on February 24, in order to change the delivery valve of the
pump (A) of the reactor sea water system of Unit 5, we stopped the pump
(C) of the reactor sea water system. As a result, the cooling of the
spent fuel pool was stopped. (the temperature of the spent fuel pool at
the time : approx 17.4°C) The temperature of the spent fuel pool will
increase approx. 0.3°C per hour during the stoppage.
- At 8:21 am on February 24, water flow at the 2nd Cesium adsorption
apparatus tends to decrease, so we stopped it to wash the filters device
by reversing the water flow.
- At 9:40 am on February 24, we started the work to add the flow-meters to
the nitrogen injection line at the side of Primary Containment Vessel of
Unit 1 in order to improve the reliability of nitrogen injection
activity. Due to this work, we suspended the nitrogen injection task
temporarily (*).
* 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
have suspended the work of nitrogen injection at the side of Primary
Containment Vessel of Unit 1 by conducting a planned shift beyond the
range of operational limitation (at 9:40 am on February 24).
·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.
Appendix: Past Progress (As of 10:00 am on February 24, 2012) (PDF 739KB)
Appendix: Past Progress (From March 11, 2011 to July 31, 2011) (PDF 225KB)
* Revised past progress
