You enter the basement of your cabin.
A long time ago, you had a small, basic interest in the science of nuclear energy. I mean, you enjoyed the idea of harnessing the power of splitting an atom in order to create massive amounts of energy. From the outside, it seemed as though you enjoyed it solely for the purpose of creating nukes out of that idea ([sic] openheimer). But, your true ideas came in the use of it in a much more dangerous way.
A few decades ago, the US government (this is in our time, there's no telling how far away the actual time was to this point in the comic) created a weapon that used a nuclear reactor as a generator in a guided missile. This consumed air that it passed and turned it into super fuel. It could fly around an entire continent, consuming air, turning it into nuclear waste, and then dropping several miniature nukes on the way to the main target, which it carried a super nuclear warhead.
This device was never officially used, but the prospects of this device could be catastrophic. This is what piqued your interest at that time, the use of a missile, which dropped mini nukes, and left a path of death on its way to the target. If you were in charge of nuclear superpower at that time, you bet your pretty ass that you'd totally use it on some unsuspecting country.
Now, this basement started out as a storage place, but over time, your grandfather, then later you, would build it up as a secure place in the case that actual nuclear calamity, or any calamity shall befall in the world. It has tons of food, water, games, bedding, and lots and lots of technological devices that could be used in bunker and out of bunker, to make the family name known all around the post-apocalyptic world.
Now, you doubt that any of this stuff could be useful on the island, seeming that the nearest city is about a thousand miles away, but still, a girl can dream.