Is there a minimum size to explosions for a nuclear device

Writing a soft scifi about an asteroid mining disaster. I explain they use a tool that is meant change the chemical properties of certain compounds into a liquid state, so they can syphon it and transport it easier. One of these devices malfunctions and causes an explosion. They are in a massive station comparable to a skyscraper drilled into this asteroid. This explosion should only take out less than half of the station. Are nuclear explosions by default massive or can they be small like the mini nuke missiles in fallout. Bonus question. Would the consequences of a hole in a porthole window be detrimental, or could it be easily clogged? How long would it take you to suffocate if you were in your sleeping quarters.