The U.N. agency concerned with the safety and peaceful use of nuclear technology is:

International Atomic Energy Agency

The International Atomic Energy Agency (IAEA) was established in 1957. It came into being to implement US President Dwight Eisenhower’s “Atoms for Peace” proposal. It seeks to promote the peaceful use of nuclear energy and to prevent its use for military purposes. IAEA teams regularly inspect nuclear facilities all over the world to ensure that civilian reactors are not being used for military purposes.