Another clue (since I'm re-reading that classic, and nobody seems to be taking my steering).
In the book that I'm thinking of, on of the incidents was described as a
meltdown. There was
another explosion not specified as a
meltdown, but also politically important. But I'm only counting the
meltdown.
When did the term "meltdown" enter English? Even the rather peculiar English of SF authors who worked for the military (if not the Manhattan Project) during the Great Patriotic War (Mk2). By the time this was first published, Sellafield (Winscale/ Calder Hall) had yet to have it's first little incident. Was there a Big Bad Thing that happened in the States which was public knowledge by the Korean War?
Wiki tells me ... The
BORAX-1 test led to a (deliberate) meltdown, but that's too late to have been in the general public's version of English by the publication. (And as a biochemist in a shipyard, the Good Doctor was unlikely to have a nuclear clearance.) The Canadian
NRX meltdown was just barely within the credible time interval to have been in the language for Asimov to use, but would his audience have understood? Apparently, Jimmy Carter, future president, was part of the clean-up crew. That would have made the War Room (no fighting!) an interesting place during TMI.
Or ... is my copy one that was edited later? It has a prelude that refers to events in Asimov's late 1970s and early 1980s life -
was he in the habit of retconning new editions of his works?
I can't think of a chemical process which Asimov would have been likely to work with that would have featured a "melt down". There are plenty of chemical reactions that can exponentially accelerate, but outside the field of explosives, generally you engineer-out that possibility. Putting reactants into solution with considerable excess of solvent is one common technique for damping down such possibilities - by which point control of pumping/ mixing gives quite fine control over reaction rates. The process of chemical education is in no small part about encouraging people to learn to think ahead of such exponential events and prevent them happening. I can't see Asimov having had the
nous to invent the term. So ... the edition I have must have a retconned meltdown in it.
When someone works out what the original book/ universe was, maybe someone has an older edition pre-retconning. My retconned edition is a digital edition citing dates into the mid-1990s, but with an internal
terminus post quem of October 1982.