The Effect of Nuclear Weapons in Space
Given the limitations of nuclear weapons lethality, I explored another use while writing a hard science space combat sequence in my book Endangered Species, being used for the soft kill. While nuclear explosions in space may not possess the punch they do within the atmosphere, they do spill a great deal of radiation into the local area. That, coupled with the intense light, makes for a prefect recipe for a spaceborne flash-bang, allowing for a good ship captain to sneak some missiles or kinetic projectiles during the confusion.
Other uses of Nukes in Space
Nuclear Pulse Propulsion
First proposed in 1947, and experienced with during the 1950's and 1960's, nuclear pulse propulsion promised to have humans orbiting Saturn by 1970. This interstellar drive system explodes nuclear bombs for thrust at the rear of the vessel, and via a series pusher plates, the vessel is pushed to achieve about 10% to 15% of light-speed (under constant acceleration). The project was abandon due to the Outer Space Treaty of 1967, and that using the drive system for lift-off could be fatal to the crew. It was determined that if there would be nuclear pulse propulsion ship than it needed to be constructed in space, which only became semi-possible when the ISS was finished. So, how long would it take for a Nuclear Pulse Propulsion starship to get to Alpha Centurai? About 85 years. Somebody better pack the complete Dr.Who series. One of the few visual works on nuclear pulse propulsion was the 2009 Ronald Moore pilot Virtuality which is on DVD, very much worth checking out.
Spaceborne Nuclear Weapons in Sci-Fi
Examples of Nukes in Space in Sci-Fi
Star Trek: Enterprise
While the advanced Asgard race helped the Earth (mostly the United States) develop several deep space warships, like the Daedalus, but refused to arm the Terran warships. So, the rescuers of the ancient alien city of Atlantis were confined to human weapons of the 20th century, two types of nuclear missiles and rapid-fire rail guns (mostly likely are Gauss Guns in reality). It was only later, when the Asgard race died out, that the 304 class warships were rearmed with alien plasma beam cannons.
Star Trek: TOS
The jolt that sent Luna off scream through the Cosmo was a massive nuclear explosion on the dark side of the moon. It seems that in the universe of Space:1999, the moon is a safe-site for Terran nuclear waste, and much of the waste is stored below the surface, and transported around by specially outfitted Eagle transports. On a couple of Space:1999 sites, there is machinery labeled 'laser/nuclear control', which leads me to believe that some of the Eagle transports can be armed with ship-to-ship missiles with nuclear warheads.