U.S. Nuclear Testing Program in the Marshall Islands

During the period from June 30, 1946, to August 18, 1958, the United States conducted 67 nuclear tests in the Marshall Islands, all of which were considered atmospheric. The most powerful of those tests was the "Bravo" shot, a 15 megaton device detonated on March 1, 1954, at Bikini atoll. That test alone was equivalent to 1,000 Hiroshima bombs.

While the Bravo test is well known, it should be acknowledged that 17 other tests in the Marshall Islands were in the megaton range and the total yield of the 67 tests was 108 megatons, the equivalent of more than 7,000 Hiroshima bombs.

For the sake of comparison, it may be noted that from 1945 to 1988, the U.S. conducted a total of 930 known nuclear tests with a combined yield estimated to be 174 megatons. Approximately 137 megatons of that total was detonated in the atmosphere. In other words, while the number of tests conducted in the Marshall Islands represents only about 14% of all U.S. tests, the yield of the tests in the Marshalls comprised nearly 80% of the atmospheric total detonated by the U.S.

Under Article IV of the Section 177 Agreement, The Governments of the United States and the Marshall Islands agreed to the establishment of a Claims Tribunal which would have jurisdiction "to render final determinations of all claims past, present and future, of the Government, citizens and nationals of the Marshall Islands which are based on, arise out of, or are in any way related to the Nuclear Testing Program, and disputes arising from distributions made under Article II and III of this agreement."


U.S. NUCLEAR DETONATIONS IN THE MARSHALL ISLANDS

(Unless indicated otherwise, stated purpose of all tests was "Weapons Related")

No. Date (M/D/Y) Name Atoll Type Yield
Operation Crossroads:          
1 6/30/46 Able Bikini B-29 Airdrop (520 ft.) 23 kilotons
2 7/24/46 Baker Bikini Underwater (-90 ft.) 23 kilotons
Operation Sandstone:          
3 4/14/48 X-Ray Enewetak Tower (200 ft.) 37 kilotons
4 4/30/48 Yoke Enewetak Tower (200 ft.) 49 kilotons
5 5/14/48 Zebra Enewetak Tower (200 ft.) 18 kilotons
Operation Greenhouse:          
6 4/7/51 Dog Enewetak Tower (300 ft.) 81 kilotons
7 4/20/51 Easy Enewetak Tower (300 ft.) 47 kilotons
8 5/8/51 George Enewetak Tower (200 ft.) 225 kilotons
9 5/24/51 Item Enewetak Tower (200 ft.) 45.5 kilotons
Operation Ivy:          
10 10/31/52 Mike (1) Enewetak Surface 10.4 megatons
11 11/15/52 King Enewetak Airdrop 500 kilotons
Operation Castle:          
12 2/28/54 Bravo (2) Bikini Surface 15 megatons
13 3/26/54 Romeo Bikini Barge 11 megatons
14 4/6/54 Koon Bikini Surface 110 kilotons
15 4/25/54 Union Bikini Barge 6.9 megatons
16 5/4/54 Yankee Bikini Barge 13.5 megatons
17 5/13/54 Nectar Bikini Barge 1.69 megatons
Operation Redwing:          
18 5/4/56 Lacrosse Enewetak Surface 40 kilotons
19 5/20/56 Cherokee Bikini Airdrop 3.8 megatons
20 5/27/56 Zuni Bikini Surface 3.5 megatons
21 5/27/56 Yuma Enewetak Tower (205 ft.) .19 kilotons
22 5/30/56 Erie Enewetak Tower (300 ft.) 14.9 kilotons
23 6/6/56 Seminole Enewetak Surface 13.7 kilotons
24 6/11/56 Flathead Bikini Barge 365 kilotons
25 6/11/56 Blackfoot Enewetak Tower (200 ft.) 8 kilotons
26 6/13/56 Kickapoo Enewetak Tower (300 ft.) 1.49 kilotons
27 6/16/56 Osage Enewetak Airdrop (600-700 ft.) 1.7 kilotons
28 6/21/56 Inca Enewetak Tower (200 ft.) 15.2 kilotons
29 6/25/56 Dakota Bikini Barge 1.1 megaton
30 7/2/56 Mohawk Enewetak Tower (300 ft.) 360 kilotons
31 7/8/56 Apache Enewetak Barge 1.85 megatons
32 7/10/56 Navajo Bikini Barge 4.5 megatons
33 7/20/56 Tewa Bikini Barge 5 megatons
34 7/21/56 Huron Enewetak Barge 250 kilotons
Operation Hardtack I:          
35 4/28/58 Yucca Near Enewetak (3) Balloon (86,000 ft.) 1.7 kilotons
36 5/5/58 Cactus Enewetak Surface 18 kilotons
37 5/11/58 Fir Bikini Barge 1.36 megatons
38 5/11/58 Butternut Enewetak Barge 81 kilotons
39 5/12/58 Koa Enewetak Surface 1.37 megatons
40 5/16/58 Wahoo Enewetak Underwater (-500 ft.) 9 kilotons
41 5/20/58 Holly Enewetak Barge 5.9 kilotons
42 5/21/58 Nutmeg Bikini Barge 25.1 kilotons
43 5/26/58 Yellowwood Enewetak Barge 330 kilotons
44 5/26/58 Magnolia Enewetak Barge 57 kilotons
45 5/30/58 Tobacco Enewetak Barge 11.6 kilotons
46 5/31/58 Sycamore Bikini Barge 92 kilotons
47 6/2/58 Rose Enewetak Barge 15 kilotons
48 6/8/58 Umbrella Enewetak Underwater (-150 ft.) 8 kilotons
49 6/10/58 Maple Bikini Barge 213 kilotons
50 6/14/58 Aspen Bikini Barge 319 kilotons
51 6/14/58 Walnut Enewetak Barge 1.45 megatons
52 6/18/58 Linden Enewetak Barge 11 kilotons
53 6/27/58 Redwood Bikini Barge 412 kilotons
54 6/27/58 Elder Enewetak Barge 880 kilotons
55 6/28/58 Oak Enewetak Barge 8.9 megatons
56 6/29/58 Hickory Bikini Barge 14 kilotons
57 7/1/58 Sequoia Enewetak Barge 5.2 kilotons
58 7/2/58 Cedar Bikini Barge 220 kilotons
59 7/5/58 Dogwood Enewetak Barge 397 kilotons
60 7/12/58 Poplar Bikini Barge 9.3 megatons
61 7/14/58 Scaevola (4) Enewetak Barge 0
62 7/17/58 Pisonia Enewetak Barge 255 kilotons
63 7/22/58 Juniper Bikini Barge 65 kilotons
64 7/22/58 Olive Enewetak Barge 202 kilotons
65 7/26/58 Pine Enewetak Barge 2 megatons
66 8/6/58 Quince Enewetak Surface 0 ("fizzle")
67 8/18/58 Fig Enewetak Surface 0.02


Notes:

(1) Experimental thermonuclear device, produced a crater 6,240 feet in diameter and 164 feet deep. Device itself weighed 164,000 lbs.
(2) Largest nuclear test explosion conducted by the United States, produced a crater 6,000 feet in diameter and 240 feet deep. Expected yield 6 megatons (presumed range 4 to 8 megatons). Cloud top 114,000 feet.
(3) Balloon detonation at 12°37' N, 169°01' E, approximately 85 miles northeast of Enewetak.
(4) "Safety experiment."



Sources:

Addendum to "Compilation of Local Fallout Data From Test Detonations 1945-1962 Extracted From DASA 1251" Volume II - Oceanic U.S. Tests, 1 May 1979, prepared by General Electric Company-TEMPO under contract to the Defense Nuclear Agency.

"Nuclear Weapons Databook Working Papers - Known U.S. Nuclear Tests" January 1989, published by Natural Resources Defense Council.

U.S. Department of Energy "List of Declassified Yields of Tests Conducted in the Pacific Prior to 1958-1961 Moratorium, December 1993."


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