https://www.gamespot.com/articles/heres-how-fallout-76s-nukes-work-and-what-they-do/1100-6461104/

Bethesda's upcoming online-RPG Fallout 76 aims to switch things up in a big way for the post-apocalyptic series. However, one new feature, and its ensuing ramifications, has gotten many players talking. First revealed during Bethesda's E3 2018, Fallout 76 will allow players to gain access to a stockpile of nuclear weapons hidden in post-apocalyptic West Virginia and decimate areas of the map. While talking about the new mechanics of Fallout 76 at QuakeCon 2018--which includes the new leveling and perk systems--game director Todd Howard and project leader Jeff Gardner elaborated further on just how nukes will work, and how they designed it to be less of a hassle than you may think.

To gain access to the nuclear weapons, you'll need to find a set of access codes found from specific enemies in the world. These codes form a sequence, which grant you passage into one of the hidden nuclear launch facilities in the wasteland. Once you're ready to launch, you can select a specific spot on the map to send the bombs, which will lay waste to the area and everything in it. While this may seem like a largely gimmicky move, there is a benefit to letting loose with the atomic bombs. With the ensuing nuclear fallout in full effect, it will grant players access to new items, rare materials, new locations, and even more powerful enemies to fight. As a part of the end-game, the materials and resources found from these irradiated places are vital to continue progress for high-level characters. However, the chase and immediate aftermath of dropping the bombs had fans worried that it would more of nuisance than an interesting gameplay mechanic.