Chernobyl Shelter Stabilization and New Safe Confinement Structure to confine the Chernobyl Nuclear Power Plant in Ukraine, which exploded in 1986 in the worst nuclear accident in history.[1] The confinement is designed to last 100 years and replaces the original "sarcophagus" erected to contain radiation following the Chernobyl disaster.[15] Bechtel began repairs in 1998 and is now part of the team overseeing construction of the arch, which is planned to be installed over Unit 4 of the reactor in 2017.[15][16]