The long-term damage from an accident at the Chernobyl nuclear power plant more than 30 years ago is still unknow. When explosions ripped through the reactor in rural Ukraine, then part of the Soveit Union, they spewed huge amounts of radioactive material into the atmosphere and caused the worst nuclear disaster in history. About 10,000 people have died or will die because or their exposure to radiation. WIth international help, Ukraine has enclosed the damaged reactor, giving scientists time to figure out what our future holds.