to me it sounds like the lights that show that the device is in such or other position of working ( for the safety of radiations e.g.)

Usually, a 'verrrine' in this sort of context is more than just an 'indicator' (which might be flat on a panel, for example) — they are very often the kind of 'light-under-a-dome' that you find on industrial equipment — stnading proud and giving a clear warning indication over a wide field of view. A little like a smaller version of a police blue beacon, but of course, not flashing!

'beacon' is a commonly used term — and although they may often be flashing, the use of the term doesn't specifically require that — for this form of light.

I would personally prefer to use 'warning', since the function appears to be to warn when the apparatus is operating (etc.) — it is not for 'signalling' in the sense of sending messages (as by Morse code, for instance)! However, cf. the use of 'signal' for things like railway applications, and of course traffic lights — you might find that kind of application closer.

Do note, however, that there is a degree of ambiguity in the FR term — SOMETIMES, it is used just to mean an indicator light that has a relatively prominent glass (or these days, plastic) 'lens' — the kind of thing that might have a lamp inside it, rather than a simple LED 'voyant'. So it would be really helpful to glean as many other clues as you can from your text to see if you can tell where and how these are mounted, visible, etc.