Operation Hardtack II was a series of 37 nuclear tests conducted by the United States in 1958 at the Nevada Test Site. These tests followed the Operation Argus series and preceded the Operation Nougat series.
With test moratoriums on the horizon, American weapons labs rushed out many new designs. A hard deadline for testing was set at midnight (0000 hrs), 31 October 1958, as negotiations were set to start that day. Twenty-nine tests were executed in October, with four of them on the last day of the month. One test was cancelled because weather delays postponed it across the midnight deadline. After the conclusion of Hardtack II, the United States announced a unilateral testing moratorium, which the Soviet Union joined after two last tests on 1 and 3 November. In September 1961, the Soviet Union resumed nuclear testing — including the test of the most powerful nuclear device ever designed, the Tsar Bomba, in October — and the United States followed suit with Operation Nougat.
Nuclear tests Tamalpais
The Tamalpais test was conducted in the U12b.02 adit of Rainier Mesa by Lawrence Radiation Laboratory on October 8, 1958. The shot took place in a 394-foot-long hook-shaped drift ending in an unusually large test chamber lined with salt blocks as part of an experiment in preparation for Project Gnome. Additional experiments included measuring permanent tunnel displacement, seismic ground shock measurement, gas sampling by Oak Ridge National Laboratory, and electromagnetic pulse measurement by the Department of Defense Effects Test Group. The detonation of the .072 kiloton device released significant radioactive contamination and damage to the U12 tunnel complex, with radiation levels of 50R/h at the main portal and in the 10,000 R/h range in the tunnel immediately following detonation. The following day, workers reentered the tunnel and triggered a significant hydrogen gas explosion that further damaged the tunnel and injured three workers. Following the tunnel's evacuation, a second hydrogen explosion occurred later the same day.
Adams Adams was planned to be the final test of Hardtack II, but due to unfavorable winds the shot was never fired. The shot was intended to be a balloon test, and had been fully assembled and raised to firing altitude when it was cancelled. After midnight and the start of the moratorium, the device was lowered to the ground and disassembled. The Soviet Union would continue nuclear testing until 3 November.
A 31 October 1958 meeting of the Atomic Energy Commission following the cancellation resulted in the following note:
During earlier tests in Hardtack II, University of California Radiation Laboratory (UCRL, now Lawrence Livermore National Laboratory) discovered that the planned primary stage for their Polaris nuclear warhead was not one-point safe. The primary was hurriedly redesigned to remedy this issue and was to be tested in Adams.
List of nuclear tests
+ United States' Hardtack II series tests and detonations Name The US, France and Great Britain have code-named their test events, while the USSR and China did not, and therefore have only test numbers (with some exceptions – Soviet peaceful explosions were named). Word translations into English in parentheses unless the name is a proper noun. A dash followed by a number indicates a member of a salvo event. The US also sometimes named the individual explosions in such a salvo test, which results in "name1 – 1(with name2)". If test is canceled or aborted, then the row data like date and location discloses the intended plans, where known. Date time (UT) Local time zoneTo convert the UT time into standard local, add the number of hours in parentheses to the UT time; for local daylight saving time, add one additional hour. If the result is earlier than 00:00, add 24 hours and subtract 1 from the day; if it is 24:00 or later, subtract 24 hours and add 1 to the day. Historical time zone data obtained from the IANA time zone database. LocationRough place name and a latitude/longitude reference; for rocket-carried tests, the launch location is specified before the detonation location, if known. Some locations are extremely accurate; others (like airdrops and space blasts) may be quite inaccurate. "~" indicates a likely pro-forma rough location, shared with other tests in that same area. Elevation + height Elevation is the ground level at the point directly below the explosion relative to sea level; height is the additional distance added or subtracted by tower, balloon, shaft, tunnel, air drop or other contrivance. For rocket bursts the ground level is "N/A". In some cases it is not clear if the height is absolute or relative to ground, for example, Plumbbob/John. No number or units indicates the value is unknown, while "0" means zero. Sorting on this column is by elevation and height added together. Delivery Atmospheric, airdrop, balloon, gun, cruise missile, rocket, surface, tower, and barge are all disallowed by the Partial Nuclear Test Ban Treaty. Sealed shaft and tunnel are underground, and remained useful under the PTBT. Intentional cratering tests are borderline; they occurred under the treaty, were sometimes protested, and generally overlooked if the test was declared to be a peaceful use.Purpose Include weapons development, weapon effects, safety test, transport safety test, war, science, joint verification and industrial/peaceful, which may be further broken down. DeviceDesignations for test items where known, "?" indicates some uncertainty about the preceding value, nicknames for particular devices in quotes. This category of information is often not officially disclosed. YieldEstimated energy yield in tons, kilotons, and megatons. A ton of TNT equivalent is defined as 4.184 gigajoules (1 gigacalorie). FalloutRadioactive emission to the atmosphere aside from prompt neutrons, where known. The measured species is only iodine-131 if mentioned, otherwise it is all species. No entry means unknown, probably none if underground and "all" if not; otherwise notation for whether measured on the site only or off the site, where known, and the measured amount of radioactivity released. References Notes Otero 20:00:00.2 PST (–8 hrs) NTS Area U3q – underground shaft,safety experiment XW-54 ?
Venting detected,
1-point test, failed, device similar to HT-I Sequoia. Bernalillo 19:30:00.2 PST (–8 hrs) NTS Area U3h (n?) – underground shaft,safety experiment XW-54
Venting detected on site
1-point test, repeat of Otero, also failed. Eddy 14:00:00.2 PST (–8 hrs) NTS Area B7b ~ + balloon,weapons development
Venting detected,
test device successful. Luna 19:00:00.2 PST (–8 hrs) NTS Area U3m – underground shaft,safety experiment XW-54 ?
Venting detected on site
1-point test, repeat of Otero/Bernalillo, still unsafe. Mercury 22:00:00.0 PST (–8 hrs) NTS Area U12f.01 – tunnel,safety experiment XW-47 primary ?
1-point test, declared success despite yield, XW-42 test, similar to Pascal-C and San Juan devices. Valencia 20:00:00.2 PST (–8 hrs) NTS Area U3r – underground shaft,safety experiment XW-42 ?
Venting detected on site
1-point test, declared success despite yield, similar to Pascal-C and San Juan devices. Mars 00:00:00.2 PST (–8 hrs) NTS Area U12f.02 – tunnel,safety experiment XW-48
Venting detected on site
1-point test, similar to Tamalpais and Ceres. Mora 14:05:00.1 PST (–8 hrs) NTS Area B7b ~ + balloon,weapons development XW-54 Gnat
Venting detected,
Full yield test of device similar to Otero et al., fizzled. Hidalgo 14:10:00.1 PST (–8 hrs) NTS Area B7b ~ + balloon,safety experiment Moccasin
Venting detected,
This 1-point test failed; similar to Coulomb-C. Colfax 16:15:00.2 PST (–8 hrs) NTS Area U3k – underground shaft,safety experiment XW-54 Gnat
Venting detected,
1-point test of device similar to Otero et al., failed. Unstemmed shaft. Tamalpais 22:00:00.13 PST (–8 hrs) NTS Area U12b.02 – tunnel,weapons development XW-48
Full yield test, similar to Mars and Ceres. Quay 14:30:00.1 PST (–8 hrs) NTS Area 7c + tower,weapons development XW-50 ?
Venting detected,
Concept feasibility test, similar to HT-I Linden. Lea 13:20:00.1 PST (–8 hrs) NTS Area B7b ~ + balloon,weapons development XW-54 Gnat ?
Venting detected,
Full yield test of device similar to Otero et al., fizzled. Neptune 18:00:00.2 PST (–8 hrs) NTS Area U12c.03 – tunnel,safety experiment XW-47
Venting detected on site
1-point test, failed, similar to HT-I Hickory and HT-II Titania. First NTS subsidence crater at Rainier despite low yield and depth buried. Hamilton 16:00:00.2 PST (–8 hrs) NTS Area 5 + tower,weapons development XW-51 ? Quail
Venting detected,
Davy Crockett prototype test, fizzled, extremely small device (). Logan 06:00:00.14 PST (–8 hrs) NTS Area A12e.02 – tunnel,weapons development
ABM warhead test, small (, ) kiloton-range device, successful. Dona Ana 14:20:00.1 PST (–8 hrs) NTS Area B7b ~ + balloon,weapons development XW-54 Gnat
Venting detected,
Low yield test, similar to Otero et al. Vesta 23:00:00.2 PST (–8 hrs) NTS Area S9e + 0 dry surface,safety experiment XW-47 primary
Venting detected,
1-point test, failed, similar to Wrangell, Oberon, Sanford. Rio Arriba 14:25:00.1 PST (–8 hrs) NTS Area 3s + tower,weapons development Mk-7
Venting detected,
Low yield Mk-7, successful, fired on wooden tower. San Juan 14:30:00.2 PST (–8 hrs) NTS Area U3p – underground shaft,safety experiment XW-42 ?
1-point test, successful, safe design extrapolated from Pascal-C and HT-II Valencia. Unstemmed shaft. Socorro 13:30:00.2 PST (–8 hrs) NTS Area B7b ~ + balloon,weapons development XW-54 Gnat ?
Venting detected,
Full yield test of XW-54 primary, successful, similar to Otero et al. Wrangell 16:50:00.1 PST (–8 hrs) NTS Area 5 + balloon,weapons development XW-47 Canary ?
Venting detected,
Full yield test fizzle, similar to Vesta, Oberon, Sanford. Oberon 20:30:?? PST (–8 hrs) NTS Area 8a + tower,safety experiment XW-47 primary Canary ?
Venting detected,
1-point test, successful, similar to Vesta, Wrangell, Sanford. Rushmore 23:40:00.1 PST (–8 hrs) NTS Area B9a ~ + balloon,weapons development XW-47 primary Canary ?
Low yield test, fizzled, similar to Mercury, Neptune, Titania. Catron 15:00:00.2 PST (–8 hrs) NTS Area 3t + tower,safety experiment XW-54 Gnat
Venting detected,
1-point test, similar to Mora, failed, fired on wooden tower. Juno 16:01:00.2 PST (–8 hrs) NTS Area S9f + 0 dry surface,safety experiment Logan
1-point test to determine safety limits. Ceres 04:00:00.2 PST (–8 hrs) NTS Area 8b + tower,safety experiment XW-48 AFAP
1-point test of atomic artillery shell, similar to Tamalpais and Mars. Sanford 10:20:00.1 PST (–8 hrs) NTS Area 5 + balloon,weapons development XW-47 primary Canary ?
Venting detected,
Full yield test, successful, similar to Vesta, Oberon, Wrangell. De Baca 16:00:00.1 PST (–8 hrs) NTS Area B7b ~ + balloon,weapons development XW-54 Gnat
Venting detected,
Full yield test, disappointing yield, similar to Catron and Mora. Chavez 14:30:?? PST (–8 hrs) NTS Area 3u + tower,safety experiment XW-54 Gnat
Venting detected,
1-point test of device similar to De Baca, failed, fired on wooden tower. Evans 00:00:00.15 PST (–8 hrs) NTS Area U12b.04 – tunnel,weapons development XW-47 primary Canary ?
Venting detected on site
Full yield test fizzle, similar to Blanca. Mazama 11:20:?? PST (–8 hrs) NTS Area 9 + tower,weapons development
Fizzle. Humboldt 14:45:00.1 PST (–8 hrs) NTS Area 3v + tower,weapons development XW-51 ?
Venting detected,
Repeat of Hamilton with higher yield, extremely small device (16 kg).