Linear Algebra libraries, geomagnetic world models, tidal models, navigation ephemerides, ...
There's a lot of classic old school FORTRAN stuff from the 1950s that still exists albeit ported forwards.
In the nuclear DOE domain its more likely to be encoded decay tables of daughter products for coarse statistical back of envelope (with 1950s computation) guesstimates.
It wasn't until much later the US decided it could stop physical testing (above / below ground detonations) and move to sufficiently scaled and detailed digital nuclear simulations.
Linear Algebra libraries, geomagnetic world models, tidal models, navigation ephemerides, ...
There's a lot of classic old school FORTRAN stuff from the 1950s that still exists albeit ported forwards.
In the nuclear DOE domain its more likely to be encoded decay tables of daughter products for coarse statistical back of envelope (with 1950s computation) guesstimates.
It wasn't until much later the US decided it could stop physical testing (above / below ground detonations) and move to sufficiently scaled and detailed digital nuclear simulations.