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Operation Hardtack II

1958 - Nevada Test Site

Last changed 15 October 1997
1958 was a banner year for nuclear weapons testing by the U.S., with a total of 77 U.S. tests, more than the three previous record setting years combined. This burst of testing activity was partly due to building pressure for an imminent test moratorium, leading the weapons labs to rush as many device types to the test range as possible, and partly due to the accelerating momentum of the arms race of the 1950s hitting full stride. 1958 was exceeded only by the 96 tests in 1962, sandwiched as it was between a testing moratorium followed by a surprise moratorium breakout by the Soviet Union in 1961, and the imminent prospect of a permanent atmospheric testing ban.

Hardtack II included 37 tests, the largest test series so far, exceeding the 35 tests of the just completed Hardtack I. Hardtack I had focused primarily on high yield proof or developemental tests of complete thermonuclear weapons, which necessitated it be conducted in the distant Pacific (a total of 35.6 Mt being fired). In contrast, Hardtack II consisted exclusively of low yield tests, many of them attempted zero-yield one-point safety tests, which could be conducted in relative safety in Nevada (some were underground). Only 45.8 kt total was fired in Hardtack II, and of this only 18.5 kt was fired above ground. This was a dramatic turnaround from the previous Nevada test series, Plumbbob, in which the above ground Hood shot by itself was 74 kt. Concern about the effects of fallout on the U.S. was certainly making itself felt.

Most of the tests were efforts to prove the safety and effectiveness of new "sealed pit" fission primaries and tactical weapons. This task proved extremely difficult, caught between the Scylla of safety (ensuring that accidental detonation of the explosive could not create even a small nuclear yield) and the Charybdis of effectiveness (ensuring that the weapon reached its design yield). Effective designs often proved unsafe, and modifications made to achieve safety often led to fizzles. As a result, despite the large number of tests, only a fairly small number of application systems were actually under development. For example, at least 10 shots were conducted to verify the safety and effectiveness of a primary for the XW-54 warhead. No more than 7 design types account for at least 29 of the tests. This series included tests of what is probably the lightest nuclear system feasible - the XW-51 Davy Crockett warhead - weighing only 16 kg in its tested form.

The Los Alamos (LASL) shots had names taken from New Mexico counties. The Livermore (UCRL) shots had names of North American mountains, Roman gods and goddesses, and the fairies of A Mid-Summer Night's Dream.

The world's first underground nuclear test had been fired in the previous NTS series (Plumbbob Ranier), and this series introduced underground testing as a routine procedure. The intention was to reduce the fallout effects of the testing, which were raising great concern, but the "underground" testing procedures were still relatively primitive. Many of these shots were conducted in "unstemmed" holes, that is, holes not back-filled and sealed prior to testing. These shots were called "roman candles" since the incandescent gas from the fireball was ejected as a jet from the mouth of the shaft. Obviously fallout containment was much less than perfect, but most of the fission product was nonetheless deposited in the shaft instead of escaping, and the radiation that did escape was not lofted so that it could travel far downwind.

Hardtack Phase II still released some 3,140 kilocuries of radioiodine (I-131) into the atmosphere (about equal to the Trinity test), only ~5% as much as the previous test series (Plumbbob). This radiation also did not nearly spread as far, only about one-millionth as much radiation exposure occurred to civilians. The total civilian radiation exposures was a mere 160 person-rads of thyroid tissue exposure. The odds are about 20-1 against this producing even one additional cancer case. Chart of fallout exposures from "Hardtack Phase II" (51 K, 539x577). From National Cancer Institute Study Estimating Thyroid Doses of I-131 Received by Americans From Nevada Atmospheric Nuclear Bomb Test, 1997. To go to the National Cancer Institute and get the full report, click here.



Test:Lea
Time:13:20 13 October 1958 (GMT)
Location:NTS, Area 7b
Test Height and Type:Balloon, 1500 Feet
Yield:1.4 kt

This was a fizzled attempt to fire the LASL designed XW-54 primary at full yield. One of many (at least ten) shots that attempted to verify safety and effectiveness of this device in several variants (not even counting at least two safety shots - Pascal A and B - attempted in Plumbbob). This was probably a version of the Gnat device, and was similar to devices fired in Hardtack II Otero, Bernalillo, Luna, Mora, Colfax, etc.

Device dimensions: 11.7 inches in diameter, 15 inches long, weight 63 lb.

In the picture below, spikes can be seen propagating down the mooring cables of the balloon. These were termed "rope tricks" by Dr. John Malik, and are caused by thermal energy from the fireball surface vaporizing the cables.

Hardtack II LeaHardtack II Lea (14 K)

Click here for a larger picture (34 K)


Test:Socorro
Time:13:30 22 October 1958 (GMT)
Location:NTS, Area 7b
Test Height and Type:Balloon, 1450 Feet
Yield:6 kt

Finally a successful full yield test of the XW-54 primary! Predicted yield was 5-9 kt. Similar to the Lea device. Device dimensions: 11.7 inches in diameter, 15 inches long, weight 58.1 lb.

Hardtack II SocorroHardtack II Socorro (25 K)


Test:De Baca
Time:16:00 26 October 1958 (GMT)
Location:NTS, Area 7b
Test Height and Type:Balloon, 1500 Feet
Yield:2.2 kt

Another attempt at firing a full yield version of the XW-54/Gnat system puts in a disappointing showing. Similar to the Catron and Mora devices the 2.2 kt yield was below predictions. Device dimensions: 11.3 inches in diameter, 15 inches long, weight 66 lb.

Hardtack II De BacaHardtack II De Baca (63 K)


Test:Santa Fe
Time:3:00 30 October 1958 (GMT)
Location:NTS, Area 7b
Test Height and Type:Balloon, 1,500 Feet
Yield:1.3 kt

Similar to devices fired in many of the preceding Hardtack II shots. Based on device characteristics - 11.3 inches in diameter, 15 inches long, weight 57.3 lb. - it was probably another XW-54/Gnat attempt. Yield below predictions.

Hardtack II Santa FeHardtack II Santa Fe (15 K)


Test:Blanca
Time:15:00.00.0 30 October 1958 (GMT)
Location:NTS, Area 12e
Test Height and Type:Tunnel, -987 Feet
Yield:22 kt

UCRL test of an alternate W-47 primary in a thermonuclear system mockup. This shot was successful, the predicted yield was 20 kt. Similar to Hardtack II Evans. The device was 18 inches in diameter, 45.5 inches long, and weighed 717.6 lb.

Although it was fired in an underground tunnel, the shot still vented radioactive material into the atmosphere (visible in the picture below).

Hardtack II BlancaHardtack II Blanca (59 K)


Operation Hardtack II Summary

Legend:WD=Weapons Development, ST=Safety Test, TN= Thermonuclear, LASL=Los Alamos Scientific Laboratory, UCRL=University of California Radiation Laboratory (later Lawrence Livermore), sim.=similar, HT=Hardtack
Test Name Time and Date (GMT) Location Test Type Height (Ft) Yield - Actual (Predicted) kt Sponsor Purpose Comments
Otero 20:00 12-Sep-58 NTS, Area 3q Unstemmed Shaft -480 0.038 (0-0.040) LASL ST 1-point test, failed, probable XW-54 (Gnat device) test, similar to HT-I Sequoia
Bernalillo 19:30 17-Sep-58 NTS, Area 3h Unstemmed Shaft -456 0.015 (0-0.040) LASL ST 1-point test, repeat of Otero, still unsafe
Eddy 14:00 19-Sep-58 NTS, Area 7b Balloon 500 0.083 (0.075-0.15) LASL WD 146 lb, 17.4 device test successful
Luna 19:00 21-Sep-58 NTS, Area 3m Unstemmed Shaft -484 0.0015 (0-0.040) LASL ST 1-point test, repeat of Otero/Bernalillo, still unsafe
Mercury 22:00 23-Sep-58 NTS, Area 12f Tunnel -183 Slight (0-0.010) UCRL ST 1-point test, declared success, XW-47 primary, similar to HT-I Juniper device
Valencia 20:00 26-Sep-58 NTS, Area 3r Unstemmed Shaft -484 0.002 (0-0.040) LASL ST 1-point test, declared success despite yield, XW-42 test, sim. to Pascal-C and San Juan devices
Mars 0:00 28-Sep-58 NTS, Area 12f Tunnel -140 0.013 (0-0.010) UCRL ST 1-point test for XW-48, similar to Tamalpais and Ceres
Mora 14:05 29-Sep-58 NTS, Area 7b Balloon 1500 2 (9-15) LASL WD Full yield test of device sim. to Otero et al, probable XW-54 (Gnat device), fizzled
Hidalgo 14:10 5-Oct-58 NTS, Area 7b Balloon 377 0.077 (0-0.040) LASL ST 1-point test of Moccasin, failed, similar to Coulomb-C
Colfax 16:15 5-Oct-58 NTS, Area 3k Unstemmed Shaft -350 0.0055 (0-0.040) LASL ST 1-point test of device sim. to Otero et al, probable XW-54 (Gnat device), failed
Tamalpais 22:00.00.1 8-Oct-58 NTS, Area 12b Tunnel -407 0.072 (0.100-0.300) UCRL WD Full yield test of XW-48, sim. to Mars and Ceres
Quay 14:30 10-Oct-58 NTS, Area 7c Tower 100 0.079 (0.075-0.150) LASL WD Concept feasibility test, sim. to HT-I Linden, possible XW-50 primary
Lea 13:20 13-Oct-58 NTS, Area 7b Balloon 1500 1.4 (9-15) LASL WD Full yield test of device sim. to Otero et al, probable XW-54 (Gnat device), fizzled
Neptune 18:00 14-Oct-58 NTS, Area 12c Tunnel -110 0.115 (0-0.010) UCRL ST 1-point test of XW-47 primary, failed, sim. to HT-I Hickory and HT-II Titania
Hamilton 16:00 15-Oct-58 NTS, Area 5 Tower 50 0.0012 (0.020-0.050) UCRL WD XW-51 Davy Crockett (Quail device) prototype test, fizzled, extremely small device (16 kg)
Logan 06:00.00.1 16-Oct-58 NTS, Area 12e Tunnel -932 5 (3-7) UCRL WD ABM warhead test, small (28.6 kg, 28cm x 29cm) kiloton-range device, successful
Dona Ana 14:20 16-Oct-58 NTS, Area 7b Balloon 450 0.037 (0.050-0.080) LASL WD Low yield Gnat device test, similar to Otero et al
Vesta 23:00 15-Oct-58 NTS, Area 9e Surface 0 0.024 (0-0.010) UCRL ST 1-point test of XW-47 primary, failed, sim. to Wrangell, Oberon, Sanford
Rio Arriba 14:25 18-Oct-58 NTS, Area 3s Tower 72.5 0.090 (0.100-0.150) LASL WD Low yield Mk-7, successful, fired on wooden tower
San Juan 14:30 20-Oct-58 NTS, Area 3p Unstemmed Shaft -234 0 (0-0.040) LASL ST 1-point test, successful, safe design extrapolated from Pascal-C and HT-II Valencia
Socorro 13:30 22-Oct-58 NTS, Area 7b Balloon 1450 6 (5-9) LASL WD Full yield test of XW-54, successful, sim. to Otero et al
Wrangell 16:50 22-Oct-58 NTS, Area 5 Balloon 1500 0.115 (5-10) UCRL WD Full yield test fizzle, XW-47 primary, sim. to Vesta, Oberon, Sanford
Oberon 20:30 22-Oct-58 NTS, Area 8a Tower 25 0 (0-0.010) UCRL ST 1-point test, successful, XW-47 primary, sim. to Vesta, Wrangell, Sanford
Rushmore 23:40 22-Oct-58 NTS, Area 9a Balloon 500 0.188 (1-1.5) UCRL WD Low yield test of XW-47 primary (Canary device), fizzled, sim. to Mercury, Neptune, Titania
Catron 15:00 24-Oct-58 NTS, Area 3t Tower 72.5 0.021 (-) LASL ST 1-point test of Gnat, sim. to Mora, failed, fired on wooden tower
Juno 16:01 24-Oct-58 NTS, Area 9f Surface 0 0.0017 (-) UCRL ST 1-point test to determine safety limits of Logan
Ceres 4:00 26-Oct-58 NTS, Area 8b Tower 25 0.0007 (-) UCRL ST 1-point test of XW-48 atomic artillery shell, sim. to Tamalpais and Mars
Sanford 10:20 26-Oct-58 NTS, Area 5 Balloon 1500 4.9 (-) UCRL WD Full yield test of XW-47 primary, successful, sim. to Vesta, Oberon, Wrangell
De Baca 16:00 26-Oct-58 NTS, Area 7b Balloon 1500 2.2 (>2.2) LASL WD Full yield Gnat device test, similar to Catron and Mora
Chavez 14:30 27-Oct-58 NTS, Area 3u Tower 52.5 0.0006 (0) LASL ST 1-point test of device sim. to De Baca (Gnat), failed, fired on wooden tower
Evans 00:00.00.2 29-Oct-58 NTS, Area 12b Tunnel -852 0.055 (2-8) UCRL WD Full yield test fizzle, XW-47 primary in TN mockup, sim. to Blanca
Mazama 11:20 29-Oct-58 NTS, Area 9 Tower 50 0 (>0) LASL WD Fizzle
Humbodt 14:45 29-Oct-58 NTS, Area 3v Tower 25 0.0078 (-) UCRL WD Repeat of Hamilton with higher yield, XW-51 Davy Crockett (Quail device) prototype, extremely small device (16 kg)
Santa Fe 3:00 30-Oct-58 NTS, Area 7b Balloon 1,500 1.3 (>1.3) LASL WD Similar to devices fired in many preceding shots, yield below predictions
Ganymede 11:00 30-Oct-58 NTS, Area 9g Surface 0 0 (0) UCRL ST 1-point test of W-45/Swan variant, successful
Blanca 15:00.00.0 30-Oct-58 NTS, Area 12e Tunnel -987 22 (20) UCRL WD Test of alternate W-47 primary in TN mockup, successful, sim. to Evans
Titania 20:34 30-Oct-58 NTS, Area 8c Tower 25 0.0002 (0) UCRL ST 1-point test of original XW-47 primary, declared safe despite yield, sim. to HT-I Hickory and HT-II Neptune


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