Chinese Foreign Minister Wang Yi stands with Russian Deputy Foreign Minister Sergey Ryabkov (left) and Iranian Deputy Foreign Minister Kazem Gharibabadi (right) before a meeting regarding the Iranian nuclear issue at Diaoyutai State Guest House in Beijing on Thursday. Pool Photo/via AP hide caption
Hayden Station, a coal-fired power plant, dominates part of the landscape between Hayden and Steamboat Springs in northwest Colorado. The power plant is expected to start shutting down before the end of the decade. Scott Franz/KUNC hide caption
A tunnel in the underground PULSE laboratory in Nevada, where scientists conduct experiments to test nuclear weapons without detonating them. NNSS/NNSA hide caption
The flag of the International Atomic Energy Agency flies in front of its headquarters during an IAEA Board of Governors meeting in Vienna, Austria. Heinz-Peter Bader/AP hide caption
The bridge of the NS Savannah, equipped with weather and communication instruments, would send orders to the reactor control room. Meredith Rizzo for NPR hide caption
Japan plans to release more than a million tons of nuclear waste water into the Pacific. Christopher Furlong/Getty Images hide caption
A woman in Simferopol, Crimea, watches a TV broadcast of Russian President Vladimir Putin's annual state of the nation address on Tuesday. Putin announced Russia is suspending participation in the New START nuclear weapons treaty. AFP via Getty Images hide caption
The Diablo Canyon nuclear power plant was scheduled to be shuttered in 2025. But California Governor Gavin Newsom now wants to expand its lifespan. Michael Macor/The San Francisco Chronicle via Getty Images hide caption
North Korea's flag is seen on a TV screen during a South Korean news program in this file photo from Oct. 10, 2020. Lee Jin-man/AP hide caption
The Doomsday Clock reads 100 seconds to midnight, a decision made by the Bulletin of the Atomic Scientists that was announced Thursday. The clock is intended to represent the danger of global catastrophe. Eva Hambach/AFP via Getty Images hide caption
A historical sign memorializes the March 28, 1979, partial meltdown at Three Mile Island nuclear power plant. Brett Sholtis/WITF hide caption
U.S. Ambassador to the International Atomic Energy Agency Jackie Wolcott at a board of governors meeting in Vienna, Austria on Wednesday. Alex Halada/AFP/Getty Images hide caption
Entering the control room at Three Mile Island Unit 1 is like stepping back in time. Except for a few digital screens and new counters, much of the equipment is original to 1974, when the plant began generating electricity. Jeff Brady/NPR hide caption
Secretary of Energy Rick Perry testifies during a House Energy and Commerce Committee hearing on Capitol Hill in Washington, D.C., on Oct. 12. Perry's proposed rule to benefit nuclear and coal power plants has been rejected by a federal regulatory commission. Drew Angerer/Getty Images hide caption
A Hawaii Civil Defense Warning Device, which sounds an alert siren during natural disasters, is shown in Honolulu on Nov. 29, 2017. The alert system is tested monthly, but now Hawaii residents will hear a new tone designed to alert people of an impending nuclear attack by North Korea. Caleb Jones/AP hide caption
A sign warns people not to enter the town of Ozersk, Chelyabinsk region, Russia, which houses the Mayak nuclear facility. In 1957, the nuclear reprocessing plant was the site of one of the world's worst nuclear accidents. Katherine Jacobsen/AP hide caption
The core of the RBT-3 reactor at the Research Institute of Atomic Reactors in Dimitrovgrad, Russia. Some scientists suspect the institute's work on medical isotopes might explain radioactivity detected over Europe. Sovfoto/UIG via Getty Images hide caption
A map from French authorities suggests that the release came from the east, near the border of Russia and Kazakhstan. IRSN hide caption
Cooling towers at the Three Mile Island nuclear power plant in Middletown, Pa., earlier this month. Matt Rourke/AP hide caption
Kikue Takagi, left, narrowly survived the Hiroshima atomic bombing as a schoolgirl. She's now 83. Her second cousin is U.S. Rep. Mark Takano, a Democrat from southern California. His grandparents and parents were all placed in U.S. internment camps in World War II. In this photo from last year, they are at a restaurant in Hiroshima, where he visited her. Courtesy of Mark Takano hide caption
Members of the 320th Missile Squadron missile combat crew work through a scenario in the 90th Operations Support Squadron's Missile Procedure Trainer on F.E. Warren Air Force Base, Wyo., in June 2014. The MPT is a simulator that allows missile crews to practice contingencies they might face while on alert. R.J. Oriez/U.S. Air Force hide caption
South Korean people watch a television broadcast at the Seoul Railway Station earlier this month reporting North Korea's surface-to-air missile launch. Woohae Cho/Getty Images hide caption
The Doomsday Clock stayed fixed at three minutes to midnight — the closest it has been to midnight since 1984. Saul Loeb/AFP/Getty Images hide caption
Castle Romeo was an American hydrogen bomb test in March 1954 at Bikini Atoll in the Pacific. It was 11 megatons, or roughly 1,000 times more powerful than North Korea's test on Wednesday. North Korea says it was a hydrogen bomb test, though the White House says it doubts the claim. Galerie Bilderwelt/Getty Images hide caption