I see where using a slower film..
Adding a foolish inconsistency to the proceedings:
It isn't using a slower film, but pulling the film to be able to capture the contrast range of the scene. The pictures posted above show the problem - empty dead black shadows and clothes where, in real life, there is stuff.
As to using ASA 25 film indoors, no it wasn't a particularly bright scene: large room, 2 sash windows, cloudy day, one table lamp. Most of the light was from the windows, the lamp was in the scene and provided a bit of shadow fill. Shooting from the position of the windows minimized shadows. In interior work it is always best if you have a light source over your shoulder. I mentioned it as an illustration that one can often get away with slow film if one has a fast lens and can hand-hold at a 1/15th.
And, of course, a tripod can really help in such situations. At 1/2 second a little bit of motion blur seems natural, as long as it isn't the subject's head.
But I agree, all this is not very helpful to the OP.
My advice in a missile silo would be to have a light source behind you, if possible. It might be quite well lit: after all nobody wants to be fumbling in the dark when doing maintenance on a nuke.