If the spool was a solid plate on both sides and the film had a paper overwrap, it's probably fine. Microfilm is commonly packaged this way, intended for daylight loading into a machine for exposure. Even if the paper is removed, only the outer 2-3 layers of film is exposed; the antihalation layer prevents light from penetrating any further.
Movie film is commonly packaged this way as well, on what are then called "camera spools".
If, OTOH, the spool is a spoked one (like you might see on old fashioned film projectors), it's probably toast to the core.