What Went Wrong at Fukishima? 24 Hours to Meltdown
A report by the IEEE (Institute of Electrical and Electronics Engineers) takes a close look at what went wrong at the Fukishima Nuclear Power Plant following the March 11, 2011 earthquake and tsunami.
With billions of dollars in research and technology invested in nuclear energy, the report identified six common-sense and seemly obvious lessons which could have minimized or prevented the impending meltdown.
A massive 9.0 quake struck at 2:46 pm on March 11, 2011 off the east coast of Japan. At the Fukushima Dai-ichi Nuclear Plant, operated by Tokyo Electric Power Co. (TEPCO), Unit numbers 1,2 and 3 of the six reactors were operating. #4, 5 and 6 were down for scheduled maintenance. The quake caused the plant to perform a routine auto-shutdown without incident.
Power outages caused by quake were widespread. Within 10 seconds, twelve diesel generators activated to power water pumps for cooling to the fuel rods. So far, all emergency procedures are working as planned.
At 2:52 pm Unit 1 using a non-electrical isolation condenser (IC) backup cooling system was cooling the reactor too quickly and a plant supervisor shut it down, per normal procedure.
Tsunami alerts predicted a 3 meter (9.8ft) high wave would strike the Fukushima prefecture. The Dai-ichi Plant is 10 meters above sea level (33 ft). For safety, non-essential personnel began evacuating plant.
The first wave struck at 3:27. With a second set of much bigger waves arriving at 3:35 pm. It has been approximately fifty minutes since the quake.
The second huge wave topped seawalls and surged through plant. It destroyed heat removal seawater pumps and inundated the control rooms controlling valves, pumps and other crucial equipment. Later, TEPCO employees would estimate the killer wave at 14 meters high (46 ft) from water stains on the walls.
Six generators located in basements were drowned and five more shut down when control rooms were flooded. Only one generator serving reactors 5 and 6, not located in a basement, continued operating. This lone functioning generator helped units 5 and 6 survive the disaster while the other reactors spiraled out of control.Continued on the next page