Short answers, pulled from the story.
The Baruch Plan was a United States proposal presented on the 14th of June 1946 to the United Nations Atomic Energy Commission. It offered to decommission all American atomic weapons and share nuclear technology in exchange for an international control authority and a universal pledge against producing atomic weapons.
Bernard Baruch wrote the bulk of the proposal, drawing on the Acheson-Lilienthal Report of March 1946. That earlier report was drafted by Undersecretary of State Dean Acheson and David E. Lilienthal at President Truman's request.
The Soviet Union rejected the Baruch Plan in December 1946, arguing that the United Nations was dominated by the United States and its Western European allies and could not be trusted to oversee atomic weapons impartially. The USSR counter-proposed that America dismantle its nuclear arsenal before any inspection system was discussed.
The International Atomic Development Authority was a body proposed under the Baruch Plan that would hold a monopoly over all nuclear activities, including mining uranium and thorium, refining ores, owning materials, and constructing and operating nuclear plants. It would fall under the United Nations Atomic Energy Commission.
Russell initially felt hopeful when the Baruch Plan was proposed. By 1961, when he published Has Man a Future?, he acknowledged the plan's merits but concluded that Congress had inserted clauses it knew the Russians would not accept, casting doubt on the proposal's good faith.
In his 2014 book Superintelligence: Paths, Dangers, Strategies, Nick Bostrom cited the Baruch Plan on page 89 as a historical example of how a power with a decisive strategic advantage might use that position to establish a benign form of global governance.