AHC: The Acheson-Lilienthal Plan Succeeds

With a PoD during or after the Trinity nuclear test in 1945, have the Acheson-Lilienthal plan - or some approximation of it - succeed. The key metric of success is whether any nation or other entity is stockpiling nuclear weapons or weapons material.

For those unfamiliar with the plan: after WW2, there was a very brief window - finally closing completely with the Berlin Crisis - where it seemed that international control of atomic energy and the elimination of atomic weapons might actually be achieved through the UN. The effort foundered on mutual distrust, the USSR's demand that the US give up its bombs before negotiating an inspection agreement, and the US's demand that the USSR negotiate an inspection agreement before we would give up our bombs.
 
This is a first crack at it...

Trinity fails; manufacturing errors in the detonators means that the weapon fizzles. Therefore, only the Little Boy bomb is released for use while the failure is studied to determine the cause and how to mitigate it. Then, the USS Indianapolis is torpedoed and sunk before reaching Tinian, with the crucial nuclear weapons components on board. With the invasion of Manchuria by the Soviets, a continuing (conventional) strategic bombing campaign, and other defeats elsewhere, the Japanese government surrenders in September, perhaps, ending World War II.

No nuclear weapon has ever been used in combat, or even successfully tested, but it is known that they are in theory extremely powerful and destructive weapons. Therefore, something like the Acheson-Lilienthal plan is developed to limit their spread and provide the new UN a powerful weapon for peace. Because the power of the weapons is abstract, and in any event the US doesn't have any (besides a few Fat Man-type weapons which are still untested), there is much less opposition to the idea of the US surrendering the weapons before an inspection regime is put in place, and vice-versa for the Soviet Union, so the weapons are internationalized.
 
The Soviets may have bought into this if their espionage activities were less successful and/or they were much further away from developing their own bomb. Under these circumstances, the Acheson plan is a gift: it spares them the expense of building a nuclear weapons program from scratch and facing a decade of a US monopoly on them.
 
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