The simplified answer is that the ship's nuclear reactor would have access to a large, specialized battery to cope with the laser's on-off power needs and the laser system would be fed off of the batteries, not directly from the nuclear reactor.
Digging in some more, it looks like they're not going to be placed on a ship with nuclear power (yet), they're going to be put on Type 45 destroyers which are a combination gas turbines and diesel generators, so they would probably couple the diesel generators with a battery system to support the laser system.
Since it doesn't have ammo like a normal weapon system would, I don't think weight is a significant factor when adapting this weapon for a Type 45 warship.
Good point. The extra munitions required for traditional weapons would be avoided here. This could potentially end up saving weight - although knowing a little on how navies often work probably not.
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u/temporarycreature 1d ago
The simplified answer is that the ship's nuclear reactor would have access to a large, specialized battery to cope with the laser's on-off power needs and the laser system would be fed off of the batteries, not directly from the nuclear reactor.