There are lots of illogical things regarding the nukes of Fallout 3.
Just look at "Minefield". Several wooden houses, all still standing but a totally demolished beton building stands right next to them.
Unless the building was, for some strange reason , blown up at some point after the war this makes no sense at all.
Also take a look at the White House which is propably supposed to be "ground zero". Nearly all buildings right next to it are still standing and show very little damage while others that are much farer away are totally destroyed.
Although i understand that for gameplay and fun reasons you cannot make the Capital Wasteland a giant flattened glass field for sake of realism, these two things are peticular rediculous and awkward pieces of level design. They just scream "This makes no sense" to you.
Maybe this is the result of the devs scaling the DC area down in size. In the latest interview with Todd Howard he confirmed that the DC Area was twice as big in a earlier version of Fallout 3 but was brought down to its current size as "players got lost too easily" and this was not really fun from a gameplay perspective.
So they propably erased entire sections of the map and just stitched the key zones together in the end.
Or what about Adams Air Force Base ? A high profile military target still stands almost unscratched while Fort Bannister was leveled ? Air Force bases would be among the TOP TEN most important targets for nuclear attack. Every single one of them would recieve adequate attention.
But it seems that only the ready-airfield next to the runways which were not part of the map have been bombed. Almost needlessly btw. As not a single plane or wreckage of them can be found throughout the base. It seems all birds got into the air in time.
Of course, it is absolutely plausible that not every target would be hit in a nuclear war.
Bombers would get shot down before reaching their targets, missles would get intercepted , submarines would get sunk before being able to fire their missiles, missile bases would get nuked before being able to launch a single missile of their own.
But that again is the point that screams for a continuation of the Fallout bible.