Same is true for the VA, if I remember correctly. And, for working at such facilities as a civilian. Because the Federal Gov't doesnt maintain a licensing board, they simply require that you are licensed. Once licensed in ANY state, you can work at ANY Federal facility.
Technically speaking, Federal facilities don't fall in 'State' territories. It's kind of like the 'embassy' concept. Embassies are the national territory of the country that owns them, not the countries where they are located. And Federal facilities are Federal domain, not State.
That doesn't mean that you aren't regulated. Your responsibilities, and the reporting for your failure to meet them, goes back to your original State of licensure, regardless which Federal facility you work at.
But because of the mobility normally involved with working for the Federal gov't, requiring independent licensure in every State the Federal gov't deals with would be far too cumbersome.
Actually, this is true whether you work for the Federal Gov't or not. And THAT is why the National Compact will attract more and more States until EVERY State is a member. It's the same concept.
I can already work in 20 States with my Texas license. New Orleans learned the hard way last year about NOT doing so. Because Miss is a compact State, help flowed in. In LA, however, a crippled State gov't was forced to hurry up and issue provisional licenses to get such help.
List of Compact States: