Other Press Conferences
Other Press Conferences
March 2012 Federation of Electric Power Companies of Japan Press Conference with Chubu Electric President
March 16, 2012
Chubu Electric Power Co.,Inc.
- March 11 marked the passage of one year since the Tohoku-Pacific Ocean Earthquake. The serious accident that took place at Tokyo Electric Power Co., Inc.'s Fukushima Daiichi Nuclear Power Station forced large numbers of people to live as evacuees, a circumstance that many are still facing today. They are also undergoing great hardships as they engage in efforts for reconstruction. I offer my heartfelt prayer that the victims of the earthquake may return to their normal lives as soon as possible.
- Today, I will be talking about:
- Tsunami countermeasures at Hamaoka Nuclear Power Station
Tsunami countermeasures at Hamaoka Nuclear Power Station
- In July of last year, Chubu Electric Power coordinated and organized tsunami countermeasures in order to pursue the still greater safety of Hamaoka Nuclear Power Station. Construction work is steadily proceeding at present.
- Now I will talk about tsunami countermeasures at the Hamaoka Nuclear Power Station using the references.
- Please look at page 2 of the references.
The Tohoku-Pacific Ocean Earthquake is said to have featured the simultaneous occurrence of "ordinary earthquake interlocking" and a "tsunami earthquake" that is not accompanied by strong tremors.
- Interlocking occurred over a very wide area, extending from the Sanriku coast to the Ibaraki Prefecture coast. This caused the magnitude (M), a measure of earthquake energy, to rise as high as 9.0. Large-scale slippage also occurred at shallow places along the plate boundaries, and it is thought that this could have caused an extremely large tsunami to occur.
- Please look at page 3 of the references.
In light of the accident at the Fukushima Daiichi Nuclear Power Station caused by a tsunami that was larger than had been envisioned, we considered the occurrence of interlocking over a very wide area that is a characteristic of an M9.0 tsunami, and added the Sea of Hyuga coast as a hypocenter area to the triple-interlocked Tokai/Tonankai/Nankai earthquake.
- We further took into account the slipping in shallow areas along the plate boundaries that is a characteristic of an M9.0 tsunami, and created a virtual M9 tsunami model in which the tsunami source area was expanded to include the area along the Nankai Trough.
- Please look at page 4 of the references.
The virtual M9 tsunami model that we hypothesized yielded calculations showing that the runup height of the virtual tsunami would be about T.P.+10 m. This would not exceed the height of the dune embankment in front of the power station, which is T.P.+10 to 15 m.
- In addition, the height of the sea wall that is presently under construction is T.P.+18 m. We consider this height to have an ample margin above the runup height of the virtual tsunami.
- As regards seismic resistance, we considered these points:
① Construction was performed to reinforce seismic resistance with the aim of withstanding ground motion as large as approximately 1,000 gal.
Even envisioning an earthquake according to the virtual M9 tsunami model, we found that:
② The Sea of Hyuga coast that was added as a hypocenter area is located far from the Hamaoka Nuclear Power Station, so that the tremors would be so attenuated that it would be unlikely to extend as far as the station.
③ The sedimentation at the shallow areas along the plate boundaries is relatively soft, making strong tremors less likely to occur.
For reasons such as these, we believe that the impact on the station site would be slight, so that the station can be assured of safety in terms of seismic resistance.
- The Central Disaster Management Council is presently carrying out studies and other examinations of tsunamis and earthquakes, and we will respond appropriately to future new findings.
- I will now talk about the specific content of tsunami countermeasures.
Chubu Electric Power has acted to incorporate the findings obtained to date regarding various events, including the accident that took place at Tokyo Electric Power Co., Inc.'s Fukushima Daiichi Nuclear Power Station due to the Tohoku-Pacific Ocean Earthquake, in formulating tsunami countermeasures at the Hamaoka Nuclear Power Station. Our aim with these tsunami countermeasures was to further heighten the safety of the Hamaoka Nuclear Power Station.
- Please look at page 7 of the references.
Our tsunami countermeasures include, first of all, the placement of a sea wall, the addition of embankments to a portion of the dune embankment in front of the power station and at either end of the sea wall as well as other such work to prevent flooding within the power station site. We also decided to take steps to assure the reliability of the waterproof doors in the building exterior walls in order to prevent the building interiors from flooding even if flooding occurred on the station site.
- We also took steps so that the nuclear reactor could be positively and safely brought to a cold shutdown even if the power station were to lose all AC power and the seawater cooling function as well. This was done by working to strengthen emergency countermeasures in terms of redundancy and diversity so as to assure the cooling function
- Now, therefore, I will explain the current status of work on the principal
Please look at page 9 of the references.
The construction work on tsunami countermeasures amounts to 30 items. The work to install sea wall and emergency seawater intake systems and so on is large in scale and lengthy in terms of time. The work was begun in the autumn of last year and is progressing steadily toward completion in December of this year.
- As to the status of sea wall construction, please look at page 10 of the
A total of 1.6 km in length of sea wall was installed to a height of T.P.+18 m on the reverse side of the dune embankment that is on the ocean side of the power station site, as well as on some parts of the side surfaces. The two ends were made with embankments to a height of T.P.+18 to 20 m. This connected the sea wall to ground that is T.P.+20 m or more in height.
- Construction of the main body of the sea wall began on November 11 of last year.
- Page 11 of references: Work is presently proceeding both day and night on a foundation with steel and other reinforcement at the Hamaoka site. As of yesterday (March 15), 94 of a total of 218 foundation sections had been completed.
- Page 12 of references: Work on fabricating the vertical walls is also underway at a manufacturing plant. These will be delivered to the power station site, and will begin to be installed successively from around mid-April, starting where the foundation work has been completed.
- Please look at page 13 of the references.
We will install new emergency seawater intake systems (EWS) for alternative seawater cooling function on Reactors No. 3 to 5. By installing seawater intake pumps in newly built waterproof pump rooms, we will maintain the seawater cooling function without being affected by flooding. We will also place connecting tunnels to link them with the intake water ponds for Reactors No. 2 to 5 in order to provide multiple water intake sources.
- Page 14 of references: Work is presently underway on placing the steel reinforcement for the new pump rooms at Reactors No. 3 and 4, as well as excavation of the new pump room for Reactor No. 5.
- Please look at page 15 of the references.
In addition to this work, construction has also been underway since November of last year to reinforce emergency countermeasures. This includes the installation of gas turbine generators and power panels to provide electric power to equipment that cools the reactor core and other such facilities. We have also begun construction work to prepare high ground for installation of an emergency materials and equipment storehouse and other such facilities.
- Page 16 of references: Chubu Electric Power will proceed meticulously and conscientiously to carry out tsunami countermeasure construction work with the goal of completion in December of this year.
- Finally, I will talk about disaster management measures.
- Please look at page 17 of the references.
We are presently studying the revision of our disaster management system to anticipate combined disaster with the simultaneous occurrence of earthquake, tsunami, and nuclear accident.
- The gist of the present study can be summarized in these two main points:
- In addition to preparing a system for accident prevention, we will also strengthen disaster prevention systems that anticipate the occurrence of serious accidents.
- We will take steps to strengthen our coordination with national and local governments in order to enable smoother implementation of measures to broadcast information to local communities, to conduct screening of evacuees, and so on.
- These points are still under study, and we are not at the stage where we can describe the substance of our new measures.
- Please look at page 18 of the references.
On March 13, we conducted an emergency response drill at Hamaoka Nuclear Power Station that assumes the loss of all AC power so that the function of water injection into the reactor core was lost. The purpose was to improve our capabilities for responding to emergency situations. Going forward, we will conduct repeated training exercises that incorporate the progress we make on physical tsunami countermeasure facilities as it occurs, and as we heighten our effectiveness, we will also identify problem points and take steps for further improvement.
That is all for me. Thank you.