Measures Implemented from the Chuetsu-Oki Earthquake
Power Plant Status at the Time of the Chuetsu-Oki Earthquake in Niigata
[Time of occurrence]
10:13 PM July 16, 2007
[Hypocenter]
- Jo-Chuetsu-Oki ,Niigata(Depth 17 km)
- Lat. 35°33.4' N. Long. 138°36.5' E.
- Horizontal distance from power station: Approx. 16 km
- Magnitude: 6.8
- Seismic intensity: Upper 6: Kashiwazaki, Kariwa
- Units 3, 4, 7 stopped operation safely.
- (Units 1, 2, 5 and 6 were undergoing periodic inspection)
Measures Implemented from the Chuetsu-Oki Earthquake
Geological Surveys and Other Reviews
Earthquake proofing was improved in light of the Chuetsu-Oki Earthquake.
Earthquake proofing improvement works implemented as a result of new standards introduced in the aftermath of the Chuetsu-Oki Earthquake in Niigata (in July 2007) were completed on all units by September 2012.
Addition/enhancement of Piping Support, etc.
Internal piping and conduit supports were added or improved at between 1,400 to 3,000 sites across each plant.
Improvements to Exhaust Tubes
Supports and vibration damping equipment were added to exhaust tubes used for building ventilation, etc.
Improved Earthquake Proofing for Facilities that Open and Close
Improvements have been made to facilities receiving power from external power sources. Anchor frames and other facilities have undergone earthquake proofing improvements.
Reinforcement of Reactor Building Roofing Truss
We reinforced the roofing of reactor buildings by adding copper materials to reinforce the supporting truss framework (steel framework).
Reactor Building/overhead Crane Enhancements
Reinforcing materials were added to, and derailment prevention fittings were enlarged on the travel rail support structure for overhead cranes used to open the reactor vessel lid to prevent them from toppling over.
Refueling Equipment
Reinforcing materials were also added to, and derailment prevention fittings were enlarged and expanded on refueling equipment in a similar manner to that for overhead cranes.