This March 30, 1979, file photo shows an aerial view of the Three Mile Island nuclear power plant in Middletown, Pa. The small dome at center is where a partial meltdown occurred 32 years ago on March 28, 1979. A presidential commission later said the accident was 'the result of a series of human, institutional, and mechanical failures.' Barry Thumma/AP/File
On March 15, a sign marks the Three Mile Island nuclear power plant, where the US suffered its most serious nuclear accident in 1979, in Middletown, Pa. Energy Secretary Steven Chu has said that US regulators should press ahead with approving construction licenses for new nuclear power plants despite Japan's nuclear crisis. Jonathan Ernst/Reuters
A Pennsylvania state policeman and plant security guards stand outside the Metropolitan Edison nuclear power plant on Three Mile Island on March 23, 1979. On March 28, a pressure relief valve failed and stayed open for two hours. Operators thought it had closed and shut off an automatic emergency flow of water, exposing the fuel rods. Paul Vathis/AP/File
President Jimmy Carter talks in the control room of Three Mile Island nuclear plant with (from l.) Harold Denton, director of the US Nuclear Agency, Pennsylvania Gov. Dick Thornburgh, and an unidentified employee on April 1, 1979. 'TMI was a piece of cake compared to what they're facing over there in Fukushima,' says Mr. Denton. AP/File
John Sweitzer helps his neighbor, Mrs. David Neel, daughter Danielle, and pet dog leave the residential area next to the Three Mile Island nuclear power plant near Harrisburg, Pa., on March 30, 1979. The partial meltdown at Three Mile Island nuclear plant in 1979 routed more than 180,000 people living within 50 miles of the plant. Paul Vathis/AP/File
A cooling tower of the Three Mile Island nuclear power plant stands behind an abandoned playground in Harrisburg, Pa., on March 30, 1979. Barry Thumma/AP/File
An employee of the Three Mile Island nuclear power plant checks a radiation monitor tape across the Susquehanna River from the disabled Three Mile Island nuclear power plant, testing for possible nuclear radiation leaks on Feb. 11, 1980. Paul Vathis/AP/File
A crowd of antinuclear demonstrators holds a candlelight vigil on the 32nd anniversary of the 1979 meltdown of the Three Mile Island Unit 2 nuclear reactor outside the plant's main gate at 3:53 a.m. in Middletown, Pa., on March 28. Bradley C. Bower/AP
Antinuclear demonstrators Mary Stamos (l.), Joyce Corradi (c.), and Paula Kinary (r.) hold a candlelight vigil on the 32nd anniversary of the 1979 meltdown of the Three Mile Island Unit 2 nuclear reactor outside the plant's main gate on March 28. Bradley C. Bower/AP
Antinuclear demonstrators Raymond Cole (l.) and Kristin Cole (r.) hold a candlelight vigil on the 32nd anniversary of the 1979 meltdown of the Three Mile Island Unit 2 nuclear reactor outside the plant's main gate on March 28. Bradley C. Bower/AP
The Three Mile Island nuclear power plant in Middletown, Pa., is shown in 2005.The power plant is nestled on an island in the middle of the Susquehanna River. Carolyn Kaster/AP/File
Hardline Islamist insurgents, including the Al Qaeda-linked Nusra Front, now control a second Syrian province after Raqqa, the stronghold of the Islamic State group. But ISIS isn't allied with the Islamists who tookover Idlib.
ByMariam Karouny, Reuters
Islamist groups including Al Qaeda's Nusra Front - but not ISIS - have seized the city of Idlib for the first time in Syria's civil war, fighters and a monitoring group said on Saturday.