I read a thin paperback science fiction novel in the 80's (or maybe early 90's) that I'm nearly certain was by Asimov. The protagonist was computer literate, and somehow hacked into the nuclear arsenals of both the US and USSR, and permanently locked them up (can't remember if they were fixed to just shoot off into space, or perhaps they were locked where if one went off, they all went off).
Can you name the book?
This is a long shot similar to what Joe White wrote above about theoretical physics as the basis for shutting down weapons. But this sounds a little bit like the 1978 novel by James P. Hogan The Genesis Machine. While not Asimov, Hogan had a technical background in engineering and was known for writing relatively "hard" science fiction in a style some might compare to Asimov.
"In an America becoming repressive in the face of world tensions, Brad Clifford, a young mathematical physicist, had been virtually drafted from academia to work on defense projects. But Brad's true dedication was to bring about the unification of all fields and forces, and his theory was too wild for his superiors to take seriously. So he defied the political authorities and went AWOL to work with a fellow maverick scientist. They built the machine that his theory made possible - but the machine made all weapons impotent, and could either wreck the world or save it. And the Powers That Be wanted to control it for their own benefit......"
The part that seems to match the most is that during the ending of the book.The protagonist instead of delivering an unassailable nuclear arsenal to the military, manages to build a computer/weapons system that is self-sustaining and will automatically destroy any nuclear weapons which are launched. This ultimately
allows the nations of Earth to stop the cold war and focus on using the new physics property to reach out to the stars.
Not a novel, but there is an Asimov story about nuclear neutralization: "The Pause".
Alexander Johannison, a nuclear physicist working at the United States Atomic Energy Commission, is mystified when his Geiger Counter starts failing to detect radioactivity. Over a period of time, his colleagues also notice the same strange events, but when he finally reports to his boss, no-one will take him seriously and he realises that he is the only one who is still aware of the existence of radioactivity.
Thinking that maybe an enemy has removed all knowledge of nuclear energy and nuclear weapons and is about to invade the United States, he goes home and finds a stranger there talking to his wife. The stranger, who looks like an impossibly perfect human, explains that he is an entity from 'outside the Universe'. He has been assigned to perform an 'operation' on humanity to save them from a potential nuclear holocaust. As part of the operation, all knowledge of radioactivity has been removed from humanity for five years. Also, all radioactive elements no longer exist. After the Pause, about one hundred people, including Johannison, will have the task of re-educating humanity in the peaceful use of nuclear power.
The story ends on a sinister note, as, in discussing the visit with his wife, Johannison points out that the visitor at one point referred to the Earth as "the yard", mistakenly using its own context in the reference rather than ours. Johannison concludes that it regards the Earth as a "barnyard" and humans as mere cattle who have to be controlled.
