As far as I know, the big damage from Nuclear Weapons planetside is the massive blastwave that can pretty much scour the earth, with radiation and thermal damage bringing up the rear.
But in space there is no atmosphere to create a huge concussive and scouring blast wave, which means a nuclear weapon would have to rely on its all-directional thermal and radiation to do damage… but is that enough to actually be usful as a weapon in space, considering ships in space would be designed to handle radiation and extreme thermals due to the lack of any insulative atmosphere?
I know a lot of this might be supposition based on imaginary future tech and assumptions made about materials science and starship creation, but surely at least some rough guess could be made with regards to a thernonuclear detonation without the focusing effects of an atmosphere?
For the fun fact, shockwave do propagate in the interstellarmedium. Most likely a conventionnal nuke isn’t big enough, but we can see the shockwave from supernova explosion, and voyager did measure the moment it left the sun one.
Radiation may be another beast with a well designed bomb, it’s pretty hard to stop neutrons, and they do a lot of biological damage. However, radiation poisoning isn’t an instant dead. Like shoot a nuke, leave. Come back 2 weeks latter and everyone is dying. Radiation could definitely damage electronic but I would assume spaceship designer worked properly, and the humam will be poisonned before the electronic starts to fail. A note though. The 1/r^2 law would still apply and space is huge. Being 1km out of the explosion divides the dose by 100 compared to being 100m away. 10 km away would divide the dose by 10 000. So the death radius won’t be that big.
Okay, but now we’re comparing nukes and supernovae, and that’s kind of like comparing the erosion of a drop of water to that caused by a tsunami. Sure, the same forces may be at work, but they’re small enough to be negligible in one.
With a heavy dose of radiation you are sick extremely fast, and dead soon after. You may survive for some hours if you have medical care.
If the bomb explode next to the ship, the ship will need solid protection for people to survive.