I use the term at home, but can it be used in other situations outside of the home? Thank you.
Well, it depends on what the context for 'home' is.
If the context for 'home' is literally 'your home', the answer is that the verb 帰る and the phrase おかえりなさい or a variant of it can be used in other situations. Consider the following:
In a situation where you've gone traveling, for example, for an extended period of time. Say you've flown back, and a friend is waiting for you at the airport. Your friend may greet you with an おかえりなさい, even though you're not physically at your home.
Or, similar situation, you've gone traveling, and now you've become homesick of, say, Kyoto, your hometown. To tell a friend where you are, for example, that you'd like to go back to Kyoto, the phrase 京都に帰りたい is valid to convey the feeling that you miss home and want to go back.
The phrase おかえりなさい is mostly used in the home but can certainly be used outside it as well. For example, if someone you know moved away for a time and then came back you could tell them おかえりなさい as a "Welcome back/Welcome home."
It's important to remember that it should only be used when someone returns to a place that both would, at least abstractly, regard as "home" or a "home base" (even if it's temporary) and not just any place that someone returns to. (Eg. In some cases you might regard a campsite as a "home" to return to, so you could still say "welcome back" when someone has been out and about and has just returned).
Hope that answers the question sufficiently.
Watch this video
This is the biggest おかえりなさい call I've ever heard in my life out at the 'home situation.'
Well.. in this case, for Kuroda(ex-pitcher at Yankees), this stadium could be his home.
You can say おかえりなさい if you want to say 'welcome back' to someone.