News / Asia

    What is a Nuclear Meltdown?

    Japanese officials and nuclear experts have said they cannot rule out the possibility of a nuclear meltdown at a Japanese nuclear power plant that was badly damaged by last week's earthquake and tsunami.  Here is a quick guide to the nuclear process, what can go wrong, and how to prevent catastrophe.

    -- Nuclear power is produced by harnessing the heat produced by the splitting of atoms inside uranium - a process known as fission.

    -- Rods packed with uranium are submerged into water, and the heat produced by the nuclear reaction creates steam, which is used to power turbines that produce electricity.

    -- The nuclear reaction can be controlled utilizing rods made of neutron-absorbing material, such as boron, essentially shutting down the fission process.  But the rods still produce heat, even when control rods are in place, requiring a cooling system to maintain temperatures.

    -- When the cooling system failed at Japan's Fukushima Dai-Ichi reactor Number 2, the fuel rods boiled through the available water and were for a period of hours exposed to the air.

    -- If the rods get too hot, they can eventually melt, thus the term "meltdown."

    -- In the event of a complete meltdown, the still-burning hot nuclear fuel could drip to the floor of the reactor.  If the containment structure around the reactor is not strong enough, the fuel potentially could be exposed to the outside environment, and can have devastating consequences for nearby communities.

    -- The world's worst nuclear power disaster was in Chernobyl, Ukraine in 1986.  After an explosion at the plant, a cloud of radioactive dust spread for hundred of kilometers and was blamed for a surge of cancer deaths and birth defects. It has left some nearby towns uninhabitable to this day.

    -- People also can be exposed to radiation poisoning through contaminated food and water.  A recent U.N. study estimates the Chernobyl disaster caused 6,000 cases of thyroid cancer in children, largely through contaminated milk.

    -- Workers at the Fukushima plant are pumping seawater, treated with boron, to try to cool the overheating reactor cores.  This process, if successful, will completely shut down and destroy the reactor.

    -- After the reactors are brought under control, nuclear technicians will either have to remove the spent fuel, or try to bury the remnants in a concrete "sarcophagus" that will prevent the excess radiation from leaking out, until they can be safely removed.

    You May Like

    UN Observes International Day of Peacekeepers

    The U.N. honors 3,400 peacekeepers killed since first mission in 1948

    Video Rolling Thunder Tribute to US Military Turns into a Trump Rally

    Half-million motorcycles are expected to rumble Sunday afternoon from Pentagon to Vietnam War Memorial for rally in event group calls Ride for Freedom

    The Struggle With Painkillers: Treating Pain Without Feeding Addiction

    'Wonder drug' pain medications have turned out to be major problem: not only do they run high risk of addicting the user, but they can actually make patients' chronic pain worse, US CDC says

    This forum has been closed.
    Comments
         
    There are no comments in this forum. Be first and add one

    Featured Videos

    Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
    Chinese-Americans Heart Trump, Bucking National Trendi
    X
    May 27, 2016 5:57 AM
    A new study conducted by three Asian-American organizations shows there are three times as many Democrats as there are Republicans among Asian-American voters, and they favor Hillary Clinton over Donald Trump. But one group, called Chinese-Americans For Trump, is going against the tide and strongly supports the business tycoon. VOA’s Elizabeth Lee caught up with them at a Trump rally and reports from Anaheim, California.
    Video

    Video Chinese-Americans Heart Trump, Bucking National Trend

    A new study conducted by three Asian-American organizations shows there are three times as many Democrats as there are Republicans among Asian-American voters, and they favor Hillary Clinton over Donald Trump. But one group, called Chinese-Americans For Trump, is going against the tide and strongly supports the business tycoon. VOA’s Elizabeth Lee caught up with them at a Trump rally and reports from Anaheim, California.
    Video

    Video Reactions to Trump's Success Polarized Abroad

    What seemed impossible less than a year ago is now almost a certainty. New York real estate mogul Donald Trump has won the number of delegates needed to secure the Republican presidential nomination. The prospect has sparked as much controversy abroad as it has in the United States. Zlatica Hoke has more.
    Video

    Video Drawings by Children in Hiroshima Show Hope and Peace

    On Friday, President Barack Obama will visit Hiroshima, Japan, the first American president to do so while in office. In August 1945, the United States dropped an atomic bomb on the city to force Japan's surrender in World War II. Although their city lay in ruins, some Hiroshima schoolchildren drew pictures of hope and peace. The former students and their drawings are now part of a documentary called “Pictures from a Hiroshima Schoolyard.” VOA's Deborah Block has the story.
    Video

    Video Vietnamese Rapper Performs for Obama

    A prominent young Vietnamese artist told President Obama said she faced roadblocks as a woman rapper, and asked the president about government support for the arts. He asked her to rap, and he even offered to provide a base beat for her. Watch what happened.
    Video

    Video Roots Run Deep for Tunisia's Dwindling Jewish Community

    This week, hundreds of Jewish pilgrims are defying terrorist threats to celebrate an ancient religious festival on the Tunisian island of Djerba. The festivities cast a spotlight on North Africa's once-vibrant Jewish population that has all but died out in recent decades. Despite rising threats of militant Islam and the country's battered economy, one of the Arab world's last Jewish communities is staying put and nurturing a new generation. VOA’s Lisa Bryant reports.
    Video

    Video Meet Your New Co-Worker: The Robot

    Increasing numbers of robots are joining the workforce, as companies scale back and more processes become automated. The latest robots are flexible and collaborative, built to work alongside humans as opposed to replacing them. VOA’s Tina Trinh looks at the next generation of automated employees helping out their human colleagues.
    Video

    Video Wheelchair Technology in Tune With Times

    Technologies for the disabled, including wheelchair technology, are advancing just as quickly as everything else in the digital age. Two new advances in wheelchairs offer improved control and a more comfortable fit. VOA's George Putic reports.
    Video

    Video Baby Boxes Offer Safe Haven for Unwanted Children

    No one knows exactly how many babies are abandoned worldwide each year. The statistic is a difficult one to determine because it is illegal in most places. Therefore unwanted babies are often hidden and left to die. But as Erika Celeste reports from Woodburn, Indiana, a new program hopes to make surrendering infants safer for everyone.
    Video

    Video California Celebration Showcases Local Wines, Balloons

    Communities in the U.S. often hold festivals to show what makes them special. In California, for example, farmers near Fresno celebrate their figs and those around Gilmore showcase their garlic. Mike O'Sullivan reports that the wine-producing region of Temecula offers local vintages in an annual festival where rides on hot-air balloons add to the excitement.
    Video

    Video US Elementary School Offers Living Science Lessons

    Zero is not a good score on a test at school. But Discovery Elementary is proud of its “net zero” rating. Net zero describes a building in which the amount of energy provided by on-site renewable sources equals the amount of energy the building uses. As Faiza Elmasry tells us, the innovative features in the building turn the school into a teaching tool, where kids can't help but learn about science and sustainability. Faith Lapidus narrates.

    Special Report

    Adrift The Invisible African Diaspora