My players are about to go up against a small army of robots/drones, and they want to use an EMP weapon to neutralize them. I envision this as a machine of some sort, like a dynamo, spinning up/charging to release a burst of EMP every so often. Some questions. It is hooked up to a TL9 fusion power plant (think Fallout). A couple of questions:

1) I'm having trouble figuring out what power-to-range would be. They are basically going to want to 'blast' a building the size of an airplane hanger. Would it be feasible that a character with Engineering (Electronic) and Mechanic (Fusion Power Plant), among other techie specialties, could build something to send an EMP wave in this space?

2) If (1) is 'yes', how long would it likely take to recharge between bursts? I imagine the group might want to hit it a few times, if not actively 'spam' it, to take down the 'bots that make their HT rolls.

3) Would something like this be prone to overload or breakdown if used repeatedly in a short time?

If the answer to any of these is 'GM's call', that's great, but I try to run a gritty game, and I like to stick as close to believability as possible. Thanks in advance for any advice.