I think it is a conversation you would have with HR after you accept a position. Once you have accepted it then I would ask what their accomodations are for nrusing mothers who need to pump, that way they can tell you if they offer a nursing room and what they have done in the past. Ont thing to remember is that they are not required to pay you for your pumping breaks so that would be something you may want to address.
I pump 3xs a day and from set up to clean up it is 30 min each time. One is during my lunch but during the other two I actually take my laptop and work for at least 1/2 of it since i am entitled to 2- 15 min breaks anyways( i am pumping right now actually!). Some employers may require you to come in early or leave late to make up for the time you are pumping.