Cannikin

A complete Spartan interceptor and warhead lowered into the shot hole.

Cannikin was an underground nuclear weapons test performed on November 6, 1971, on Amchitka island, Alaska, by the United States Atomic Energy Commission.^[1] The experiment, part of the Operation Grommet nuclear test series, tested the unique W71 warhead design for the LIM-49 Spartan anti-ballistic missile.^[2]^[3] With an explosive yield of almost 5 megatons of TNT (21 PJ), the test was the largest underground explosion ever detonated by the United States.^[4]

Prior to the main five-megaton test in 1971, a 1 Mt (4.2 PJ) test took place on the island on October 2, 1969, for calibration purposes, and to ensure the subsequent Cannikin test could be contained.^[4] This test, Milrow, was included in the Operation Mandrel nuclear test series.

The Cannikin test faced considerable opposition on environmental grounds. The campaigning environmental organization Greenpeace grew out of efforts to oppose the test.

^ Mark Nuttall (2004). Encyclopedia of the Arctic. Routledge. ISBN 1579584365. the AEC instituted an extensive bioenvironmental program on Amchitka, and within a few years had completed Project Milrow, Project Long Shot, and Project Cannikin
^ "Accomplishments in the 1970s: Lawrence Livermore National Laboratory". Archived from the original on February 17, 2005. Retrieved October 9, 2006.
^ Robert Rogalski (March 14, 2007). Classification Bulletin – TNP-29 – The fact that the Cannikin event was a proof test of the W71 warhead for the Spartan missile system (Report). Archived from the original on April 26, 2023. Pursuant to section 142d of the Atomic Energy Act of 1954, you determine that the following information can be published without undue risk to the common defense and security and can therefore be declassified and removed from the Formerly Restricted Data category: The fact that the Cannikin event was a proof test of the W71 warhead for the Spartan missile system.
^ ^a ^b The containment of underground nuclear explosions. 1989. This test, by far the highest-yield underground test ever conducted by the United States, was too large to be safely conducted in Nevada

[1] Mark Nuttall (2004). Encyclopedia of the Arctic. Routledge. ISBN 1579584365. the AEC instituted an extensive bioenvironmental program on Amchitka, and within a few years had completed Project Milrow, Project Long Shot, and Project Cannikin

[ll-2] "Accomplishments in the 1970s: Lawrence Livermore National Laboratory". Archived from the original on February 17, 2005. Retrieved October 9, 2006.

[3] Robert Rogalski (March 14, 2007). Classification Bulletin – TNP-29 – The fact that the Cannikin event was a proof test of the W71 warhead for the Spartan missile system (Report). Archived from the original on April 26, 2023. Pursuant to section 142d of the Atomic Energy Act of 1954, you determine that the following information can be published without undue risk to the common defense and security and can therefore be declassified and removed from the Formerly Restricted Data category: The fact that the Cannikin event was a proof test of the W71 warhead for the Spartan missile system.

[containment-4] The containment of underground nuclear explosions. 1989. This test, by far the highest-yield underground test ever conducted by the United States, was too large to be safely conducted in Nevada

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