Do you use a different word in the UK for these situations?
"Stick it in some precious wilderness. If you wanted to preserve the biodiversity of rainforest, drop pockets of nuclear waste into it to keep the developers out. The lifespans of the wild things might be shortened a bit, but the animals wouldn't know, or care. Natural selection would take care of the mutations. Life would go on."
http://www.guardian.co.uk/books/2000/sep/16/scienceandnature...
The only reason the word reservation has a positive connotation to you is because of what it colloquially refers to in your country. It's base definition is really anything that's been reserved for a specific purpose, doesn't have to be for wildlife preservation.
I doubt whoever named this facility back during WWII-era was attempting to soften up the image of it. Given that it was part of the Manhattan Project they probably didn't even think the general public would be aware of it.
I hope to soon see 6 lane stuck-in-traffic-ways, online adultery sites, and one joyous day I will be called a passenger on a train again instead of a customer :-)
Actually, the Red Forest in Pripyat is a place where many people can't wait to go. The exclusion zone has created a very interesting nature reserve.