Content deleted Content added
→References: Rm unused LDR |
restored unit |
||
Line 76:
===Earthquake===
The 9.0 [[moment magnitude scale|M<sub>W</sub>]] earthquake occurred at 14:46 on Friday, 11 March 2011, with the [[epicenter]] off of the east coast of the [[Tōhoku region]].<ref name="Earthquake.usgs.gov"/> It produced maximum ground [[g-force]] of 0.56, 0.52, 0.56 at units 2, 3, and 5 respectively. This exceeded the seismic reactor design tolerances of 0.45, 0.45, and 0.46 g for continued operation, but the seismic values were within the design tolerances at units 1, 4, and 6.<ref name=WWN24/>{{fact|date= June 2024 |reason= The source explicitly states there is no data for units 1, 2, and 5 so this claim cannot be verified. Unit 3 is verified as 0.52 g with design basis of 0.45. Verified siesmic values for unit 6 were within the design basis.}}
Upon detecting the earthquake, all three operating reactors (units 1, 2, and 3) automatically shut down. Due to expected grid failure and damage to the switch station as a result of the earthquake, the power station automatically started up the EDGs, isolated the reactor from the primary coolant loops, and activated the emergency shutdown cooling systems.
| |||