Alvin Kaufman was a self-taught nuclear engineer working a gig for a few companies, testing the effects of nuclear war on industry and of course, what it would do to humans. Knowing firsthand what the effects were, he wanted to do something to keep his family safe.
The irony, thought, is that he approached everyone in his cul-de-sac and offered to build one big enough for everyone. They said no. So he just made one for himself and his family, filled with severals sleeping areas, a water tank, a hand cranked air filter and enough food to last several weeks.
That said, they started taking some inventory.