Breakdown: How and Why Japan's Nuclear Reactors Failed to Cool Down
POSTED: Tuesday, March 15, 2011 - 3:38pm
UPDATED: Thursday, March 17, 2011 - 3:06am
FUKUSHIMA DAI-ICHI PLANT, JAPAN— Friday's earthquake and tsunami have left this island nation devastated, and recent after-shocks are only raising fears of radiation after a nuclear plant started experiencing problems.
Reports have said radiation is leaking from the nuclear plant after an explosion and a fire at the Fukushima Nuclear Power Complex quickly increased the crisis. Japanese officials said the fire was located in a fuel storage pond in reactor number four, causing radiation to be released directly into the atmosphere. Hydrogen gas caused the explosion in the unit, and Japanese operators were trying to keep the fuel rods in the nuclear plant cool.
Officials said they were going to use helicopters to spray water onto the rods from above.
The nuclear reactors are kept cool with water so that they maintain their temperature at around 500 degrees Fahrenheit. When the cooling fails, the temperature could rise to around 2,200 degrees, a temperature hot enough to melt the fuel rods.
So what happened when the earthquake hit Japan?
After the earthquake hit, the first safety system to prevent a melt-down was activated. Control rods rose into the nuclear reactor to stop the nuclear fission— but the fuel rods were still hot. Because of the power outage that occurred after the earthquake, water was not circulated to cool down the rods.
The second safety system turned on, and the generator began spraying the rods with coolant. An hour later, that emergency generator stopped— possibly because the tsunami hit the country at that time.
The third safety system then turned on. This system converts steam traveling through the pipes into water. But the water level dropped, and temperatures continued to rise.
All thee safety measures failed.
A professor from Japan's Atomic Energy Commission, whom was involved in the construction of the Fukushima plants, said he thinks the cooling water somehow leaked from the reactor.
“The reactor's coolants must have leaked somewhere in the building,” he said Tuesday. “We thought we had taken adequate precautions for a tsunami, but what happened was beyond our expectations.”
The Japanese government warned 140,000 people to stay within their homes on Tuesday, and an estimated 70,000 people have been evacuated from a 12-mile area around the nuclear plant.
Watch the video for a full breakdown of the above.