![]() All but one of the 13 diesel generators were damaged, resulting in the loss of AC power to all facilities except reactor 6. Equipment, machinery and electrical systems in the reactor complex buildings were damaged by water filling the ground floors and any levels below. Ten minutes after the first, a 14-15 m wave arrived, surrounding the entire reactor complex.įlooding damage to the seawater intake pumps rendered all of them inoperable. The first wave (4 m) arrived in 41 minutes (A third warning update was issued a few minutes later for waves up to 10 m and all lower elevation facilities were evacuated. The Japan Meteorological Agency issued a tsunami warning for 3-4 m waves within minutes after the earthquake, soon after updating it to 6 m. After shaking subsided, emergency operations proceeded according to the facility design, including automatic reactor shutdowns, conversion to diesel generator power, setup of an emergency response center, initiation of backup reactor cooling systems, and monitoring of spent fuel pool temperature. However the violence of the ground movement damaged electrical substations and power lines, resulting in the loss of offsite power to the plant. When the earthquake struck, seismic sensors at the plant activated automatic insertion of control rods in the reactor cores to immediately stop the nuclear reactions. Photographs taken by a Fukushima Daiichi employeeĪs the second and largest wave breached the 5.7 meter sea wall. The employee testified that the company requested an alternate calculation, which returned nearly identical results, and ultimately rejected the estimate in favor of commissioning an additional engineering study. Tsunami risk had been assessed by TEPCO staff as recently as 2008, when an employee submitted a tsunami height estimate of 15.7 meters based on extensive seismic studies and the 1896 Sanriku earthquake that triggered a tsunami over 30 m high. Spent fuel pools also relied on seawater cooling to dissipate heat from continued radioactive decay. Seawater providing cooling for the reactor cores and generators was pumped in through six intakes at the shoreline. The main administration building was up slope behind the reactor complex at an elevation of 35 m. The lowest floors of the buildings were one level below ground, near sea level. ![]() Buildings for reactors 5-6 and the emergency generators were in an area 13 m above sea level. In case of emergency, 13 diesel generators provided backup power to the reactors and equipment requiring DC battery chargers.īuildings housing reactors 1-4 and facilities for waste and spent fuel were in an area 10 m above sea level. Plant facilities were powered by offsite electricity. The reactor complex was guarded by a protective seawall designed for a maximum wave height of 5.5 m. (TEPCO), contained 6 reactors, of which 3 were fully online at the time of the earthquake, generating 460-784 Mw of electricity each. The Fukushima Daiichi facility, owned by the Tokyo Electric Power Co. Locations of the 5 nuclear power plants (NPP) on the northeast coast of Honshu, Japan,Īnd tsunami run-up heights. The damage inflicted by the tsunami was not. While the earthquake damaged the external power supplies, the situation was within the capacity of normal emergency procedures. Approximately 175 km (110 mi) southwest of the epicenter, the Fukushima Daiichi power plant experienced a combination of damage from the earthquake and subsequent tsunami that set off a chain of events leading to the meltdown of three reactor cores and release of radiation into the atmosphere and ocean. Approximately 500,000 people lost their houses and were displaced.įive nuclear power plants along the northeast coast of Honshu were also affected. The Geospatial Information Authority of Japan estimated that 561 square kilometers were area inundated by the tsunami. Of the approximately 18,000 people who died, more than 90% were drowned. A t Miyako, 145 km (90 mi) NNW of the epicenter, the water reached a height of 39.7 m. Embayments on the coastline to the north saw water heights up to twice that. In the Sendai region, due west of the epicenter, the tsunami bore reached 5 km inland to a depth of 19.5 m. Protective seawalls were overrun and towns on the northeast coast of the island sustained catastrophic damage. On 11 March 2011 at 14:46 local time a Mw 9.1 earthquake near the Japan Trench triggered a massive tsunami that within 30 minutes struck the coast of Honshu, the main island of Japan. Seismic setting of the 2011 Great Japan Earthquake and nuclear power plants. The Fukushima Daiichi Nuclear Disaster - Part 1: Uncharted territory for a nuclear emergencyįor Part 2: Decades of environmental consequences, click hereġ1 March 2011, 05:46:24 UTC, 14:46:34 JST
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