Castle Bravo
first United States test of a dry fuel hydrogen bomb known as the Shrimp
Castle Bravo was the first in a series of high-yield thermonuclear weapon design tests conducted by the United States at Bikini Atoll, Marshall Islands, as part of Operation Castle. Detonated on 1 March 1954, the device remains the most powerful nuclear device ever detonated by the United States and the first lithium deuteride–fueled thermonuclear weapon tested using the Teller–Ulam design. Castle Bravo's yield was 15 megatons of TNT [Mt] (63 PJ), 2.5 times the predicted 6 Mt (25 PJ), due to unforeseen additional reactions involving lithium-7, which led to radioactive contamination in the surrounding area.
Radioactive nuclear fallout, the heaviest of which was in the form of pulverized surface coral from the detonation, fell on residents of Rongelap and Utirik atolls, while the more particulate and gaseous fallout spread around the world. The inhabitants of the islands were evacuated three days later and suffered radiation sickness. Twenty-three crew members of the Japanese fishing vessel Daigo Fukuryū Maru ("Lucky Dragon No. 5") were also contaminated by the heavy fallout, experiencing acute radiation syndrome, including the death six months later of Kuboyama Aikichi, the boat's chief radioman. The blast incited a strong international reaction over atmospheric thermonuclear testing.
The Bravo Crater is located at 11°41′50″N 165°16′19″E. The remains of the Castle Bravo causeway are at 11°42′6″N 165°17′7″E.
Bomb design
Primary system
The Castle Bravo device was housed in a cylinder that weighed 23,500 pounds (10,700 kg) and measured 179.5 inches (456 cm) in length and 53.9 inches (137 cm) in diameter.
The primary device was a COBRA deuterium–tritium gas-boosted atomic bomb made by Los Alamos Scientific Laboratory, a very compact MK 7 device.
This brief starts where responsible research should: with the source description of “Castle Bravo” as first United States test of a dry fuel hydrogen bomb known as the Shrimp. Everything that follows is an evidence route, not borrowed authority.
Why this record matters
The subject matters to the general reference register because the source frames it as first United States test of a dry fuel hydrogen bomb known as the Shrimp. Its deeper value depends on whether names, dates, institutions and citations support that framing.
The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Sep 21, 2026. The linked authority identifier is Q304419. Authority coordinates are 11.697, 165.272. None of the 1 selected statements returned an explicit reference. The first chronological checks are 1954.
The absence of detail may reflect summary conventions rather than a lack of surviving documentation. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.
- Subject orientation
- Search vocabulary
- Locating named sources
The closest primary source, responsible institution and strongest cited specialist reference.
Three-step research path
- Establish the record: confirm the title “Castle Bravo”, its source revision and the description used here.
- Expand the search: follow Castle Bravo primary sources, Castle Bravo archive and Castle research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Castle Bravo”?
- What terminology or title could unlock a more precise catalogue search?
- Which cited source is closest to the event, object or claim?
Search terms from this dossier
This entry incorporates text from “Castle Bravo” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.