Reply #67: Cannikin was the code name for the largest underground nuke test in the US

[Cannikin]

I just wanted to shake up the underground





Project CANNIKIN was a nuclear test conducted on Amchitka Island, Alaska, at 11:00 a.m., Bering Standard Time, on November 6, 1971. CANNIKIN, a slightly less-than-five-megaton device, was the largest underground nuclear test conducted in the United States. CANNIKIN was conducted to proof test a warhead for the Spartan missile, a Safeguard Ballistic Missile Defense Program. The shock registered 7.0 on the Richter scale, the seismic unit of the time. Within two days after the explosion, a crater more than one mile wide and 40 feet deep formed.

Cannikin was a big event, and though almost every nuclear event represents some kind of technical breakthrough, Cannikin is outstanding both in the number of “firsts” and in size:

First major project under the National Environmental Policy Act of 1969, which required the preparation of an “Official Environmental Impact Statement.”
Largest mined shaft in the United States with a single elevator to 6,000 feet.
Deepest 90-inch hole—6,150 feet.
Longest diagnostic canister—264 feet.
Largest off-continent diagnostic system—250 scopes with 100 percent data retrieval.
Largest load lowered downhole—over 400 tons.
Largest emplacement drill rig—1,000 ton mast.
First operational field computer system.
First successful downhole alignment with a laser beam.
First use of over 100 miles of downhole cables.
Largest cavity (52 foot diameter) mined through a mile-long shaft.

In addition, Cannikin required the use of the largest number of recording trailers. Shock mounting the trailers was a challenge because the trailers and interior instrumentation, located about 2,000 feet from ground zero, had to be able to withstand a ground upheaval of 15 feet at shot time.