Kirsten Larson - Nuclear Meltdowns

Nuclear Meltdowns

Kirsten W. Larson

On March 11, 2011, Japanese nuclear worker Takashi Sato wrote reports on his computer. It was just another day at the Fukushima Daiichi nuclear power plant about 160 miles (267 kilometers) northeast of Tokyo. The skies were clear. The sun shone. But at 2:46 p.m. everything changed.

An enormous earthquake rattled Japan. Centered 80 miles (129 kilometers) offshore in the Pacific, the Tohoku Earthquake measured 9.0 on the Richter Scale. It shook buildings for a full five minutes, sending workers ducking for cover.

That colossal quake was just the beginning. Forty-five minutes later, a wall of water struck the shore, engulfing the nuclear plant. It was a .

Japan sits in an area known as the Ring of Fire. This part of the Pacific Ocean experiences frequent volcanic eruptions, earthquakes, and tsunamis. The Tohoku Earthquake was one of many devastating earthquakes that have affected the country.

After the initial earthquake, workers rushing from buildings saw pipes bursting. Some pipes carried water to cool three nuclear reactors. The power went out, plunging the entire plant into darkness. Without power, pumps couldnt circulate cool water through the reactor. When temperatures climb high enough, the fuel rods melt. This is a nuclear meltdown. During a meltdown, the fuel may melt through the floor and dump stay hot.

A powerful explosion ripped the roof off reactor Number 1 at the Fukushima Dai-ichi nuclear power plant. The meltdown damaged four of the six reactors at the plant beyond repair.

Fast Fact

At Fukushima, temperatures reached 4,800 degrees Fahrenheit (2,649 Celsius).

Fortunately, the power plants backup power system came on after the earthquake. Diesel-fuel-powered switched on to make electricity and keep the cooling pumps operating. Unfortunately, those backup generators were located in the plants basement. When the tsunami waves struck, they ruined the generators.

Diesel generators use diesel fuela form of gasolineto create electricity. Aside from these bus-sized generators, nuclear power plants in the United States also have portable steam generators.

The earthquake and tsunami killed almost 16,000 people and injured another 5,000. The nuclear meltdown of three reactors at the plant lasted for more than a week. During that time, the Japanese government ordered people living within 12 miles (19 kilometers) of the plant to leave their homes as explosions at the plant spewed radioactive material into the sky. More than 80,000 people left, not returning home for months. Some still have not been able to return.

The nuclear meltdown was not the only disaster Japan faced after the massive earthquake. The tsunami washed away many towns and ports in a 216 square mile (560 square kilometer) area. It destroyed more than a million buildings.

The former Soviet Union built nuclear-powered submarines like this one in the 1970s. Today, the United States Navy has 74 nuclear-powered submarines.

Today, is all around us. In the United States, nuclear power plants generate 20 percent of the countrys electricity. Nuclear power also is used to diagnose and treat cancer and power submarines and spacecraft. How do we make sure nuclear power stays safe? And how can we protect ourselves when meltdowns happen?