Fukushima: The catastrophe of Japan and the future of nuclear energy

The six reactors at the nuclear plant in Fukushima-Daiichi were designed to be automatically stopped if there was an earthquake measuring over 6.2 on the Richter scale. When Japan was hit on March 11 by an earthquake of intensity 9, the strongest in its history, nuclear safety systems, as expected, stopped nuclear fission reactions in the three active reactors.
But after the nuclear shutdown, the radioactivity of the fuel is still generating about 6% of heat from the reactor at full capacity. And this heat production decreased only slowly over a period of months to years.

Fukushima and the nuclar energy

During normal operation, the core of a reactor with fuel rods is totally immersed in water and housed within a steel containment vessel. The heat produced by nuclear fission raises the temperature of boiling water to cause, and the high pressure steam produced drives a turbine to produce electricity, after passing through the turbine, the steam is condensed and cooled water returns to the core reactor, thereby achieving a constant temperature of 300 º C in the water under a pressure of about 75 atmospheres. All the reactor in the nuclear energy cooling system keeps running with power.

The earthquake crippled the grid, which was activated the emergency cooling system powered by diesel generators. Unfortunately, they were placed in a shallow part of the building complex of reactors, perhaps unwarranted confidence that the retaining walls would protect them against the sea, a tsunami and the ecology.

Future of the nuclear Energy

By the tsunami, an hour after the earthquake, the water had flooded the area where diesel generators and they stopped. Activated the emergency cooling system operated with batteries, but these were quickly exhausted.

Thereafter, he began to raise the temperature of fuel rods in the reactor core and glimpsed a disaster due to the inability to keep them fully immersed in water for losses due to boiling. Firefighters used several interconnected trucks to inject water under pressure in the reactor in the nuclear energy core affected. But the boiling water and steam became more rapidly than it could be replaced.