No description at the National Archives. Castle Films produced this film for the U.S. military -- "Operation Crossroads" US Army film # MISC-1323 and US Navy film # MN 5345. Description from Armed Forces Films for Public and Television Use: "A documentary of the Able and Baker blasts of the Atomic Bomb Test at Bikini, produced by Joint Army-Navy Task Force One."
National Archives Identifier: 88210 source file isn't in the greatest shape.

Listed at the National Archives as "Atomic Tests In Nevada, 1955." No description at the National Archives but this is an Atomic Energy Commission (AEC) film, "Atomic Tests In Nevada: The Story of AEC's Continental Proving Ground," which is about atomic testing fallout near St. George, Utah.
Decades later, St. George residents suffered increased incidence of cancer (BBC documentary "The Dragon that Slew St. George.")

Just sound & no picture for the first few minutes. Then A-bomb, etc footage.

National Archives description: "Summary: Hydrogen bomb firing under Operation Ivy at Eniwetok Island on 2 February 1954. Narration by narration by motion picture actor Reed Halley.
 Reel 1:
1) MS INT actor Reed Hadley and a doctor of Nuclear Science talking together in control room prior to the firing of the hydrogen bomb under "Operation Ivy".
2) MS officer in charge of Military Police stands and gives instructions to two patrolmen. These men are wearing shorts. The officer in charge walks back and forth, looks at his wrist watch, acts uneasy.

Listed at the National Archives as "Operation Greenhouse, 1952" but Operation Greenhouse was in 1951. No National Archives description. AEC "16mm film combined catalog" description: "Operation Greenhouse: Produced by the USAEC and the Lookout Mountain Air Force Station, USAF. For sale by DuArt Film Laboratories, at $79.67 per print.