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Operation Plumbob
Workers at Area 51 have had to endure difficult conditions since the earliest days of the facility. In the 1950s, when the focus of the base was testing the U-2 spy plane, the CIA had to cease operations and evacuate the facility due to nearby nuclear testing on the neighboring Nevada test site. Sometimes the AEC would announce tests ahead of schedule to allow nearby residents time to evacuate if they felt it was necessary, but other times the tests would remain unannounced. The results from these tests could be seen from towns 100 miles away. People in Las Vegas would often organize trips to nearby peaks and picnic in view of mushroom clouds.
In 1957, one such test called HOOD was part of an overall program called Operation Plumbob, which was designed to see if damaged nuclear bombs emitted harmful levels of radioactivity. The AEC detonated a 74-kiloton nuclear device 1,500 feet over Area 9 of the NTS. This was the most powerful airburst ever detonated over the continental United States. The AEC did not announce the test ahead of time, though they did tell Area 51 to evacuate beforehand. The resulting blast caused some minor damage at Area 51 - mostly some broken windows and doors. Radiation was a much bigger concern, and, in fact, the soil in Area 51 has absorbed a lot of radiation over years of nuclear tests.
1957 - Nevada Test Site
 Operation Plumbbob was conducted at the Nevada Test Site (NTS) from May through October of 1957. It was the sixth test series at NTS and consisted of 29 tests. Six of these were safety tests, and two did not produce any nuclear yield. This series addressed several objectives, including tactical weapon proof tests, safety tests, and component and mockup testing for thermonuclear systems to be detonated in Hardtack I, among other things. During Plumbbob 16,000 DOD personnel participated in the Desert Rock VII and VIII exercises. The LASL shots were named for deceased scientists, the UCRL shots were named for North American mountains.
Operation Plumbbob Summary
| Test Name |
Time and Date (GMT) |
Location |
Test Type |
Height (Ft) |
Yield - Actual (Predicted) |
Sponsor |
Purpose |
Comments |
| Boltzmann |
11:55 28-May-57 |
NTS, Area 7c |
Tower |
500 |
12 kt (11 kt) |
LASL |
WD |
XW-40 boosted fission warhead test |
| Franklin |
11:55 2-Jun-57 |
NTS, Area 3 |
Tower |
300 |
140 Tons (2 kt) |
LASL |
WD |
Fizzle, XW-30? boosted all-oralloy fission warhead test |
| Lassen |
11:45 5-Jun-57 |
NTS, Area 9a |
Balloon |
500 |
0.5 Tons (600 Tons) |
UCRL |
WD |
Fizzle, unboosted all-oralloy small weapon design |
| Wilson |
11:45 18-Jun-57 |
NTS, Area 9a |
Balloon |
500 |
10 kt (8 kt, 2-12 kt) |
UCRL |
WD |
XW-45X1 Swan test, gas-boosted composite pit |
| Priscilla |
13:30 24-Jun-57 |
NTS, Area 5 |
Balloon |
700 |
37 kt (40 kt) |
LASL/DOD |
WE |
Mk-15/39 primary, stockpiled device of known yield |
| Coulomb-A |
17:30 1-Jul-57 |
NTS, Area 3h |
Surface |
0 |
Zero (1-2 Lb) |
LASL |
ST |
XW-31 1-point safety test |
| Hood |
11:40.00.4 5-Jul-57 |
NTS, Area 9a |
Balloon |
1500 |
74 kt (60-80 kt) |
UCRL |
WD |
Largest atmospheric test at NTS, 2-stage thermonuclear device |
| Diablo |
11:30.00.1 15-Jul-57 |
NTS, Area 2b |
Tower |
500 |
17 kt (11-15 kt) |
UCRL |
WD |
2-stage device, some thermonuclear yield |
| John |
14:00 19-Jul-57 |
NTS, Area 10 |
Rocket |
18,500 |
1.7 kt (1.7 kt) |
DOD |
WE |
W-25 warhead for Genie air-to-air missile |
| Kepler |
11:50 24-Jul-57 |
NTS, Area 4 |
Tower |
500 |
10 kt (11 kt) |
LASL |
WD |
XW-35 ICBM warhead development, primary in thermonuclear mockup |
| Owens |
13:30 25-Jul-57 |
NTS, Area 9b |
Balloon |
500 |
9.7 kt (2-10 kt) |
UCRL |
WD |
Very small boosted plutonium device, XW-51 progenitor |
| Pascal-A |
8:00 26-Jul-57 |
NTS, Area 3j |
Shaft |
-485 |
Listed as "slight", about 55 tons (predicted 1-2 Lb) |
LASL |
ST |
1-point safety test |
| Stokes |
12:25 7-Aug-57 |
NTS, Area 7b |
Balloon |
1500 |
19 kt (10-20 kt) |
LASL |
WD |
XW-30 test, all oralloy gas-boosted system |
| Saturn |
1:00 10-Aug-57 |
NTS, Area 12c |
Tunnel |
-100 |
Zero (100 Lb) |
UCRL |
ST |
1-point safety test of XW-45X1, oralloy-Pu composite core filled with helium; first shot fired in Ranier Mesa tunnel |
| Shasta |
12:00 18-Aug-57 |
NTS, Area 2a |
Tower |
500 |
17 kt (11-15 kt) |
UCRL |
WD |
Nearly identical to Diablo, DT gas boosted Swan primary |
| Doppler |
12:30 23-Aug-57 |
NTS, Area 7 |
Balloon |
1500 |
11 kt (-) |
LASL |
WD |
Gas boosted implosion device, possible XW-34 test |
| Pascal-B |
22:35 27-Aug-57 |
NTS, Area 3c |
Shaft |
-500 |
0.3 kt (1-2 Lb) |
LASL |
ST |
1-point test for upper limits of safety, similar to Pascal-A |
| Franklin Prime |
12:40 30-Aug-57 |
NTS, Area 7b |
Balloon |
750 |
4.7 kt (2 kt) |
LASL |
WD |
Retest of Franklin with more U-235 added to core |
| Smoky |
12:30.00.1 31-Aug-57 |
NTS, Area 8 |
Tower |
700 |
44 kt (45-50 kt) |
UCRL |
WD |
TX-41 2-stage device, some thermonuclear yield |
| Galileo |
12:40 2-Sep-57 |
NTS, Area 1 |
Tower |
500 |
11 kt (-) |
LASL |
WD |
Boosted fission device, exploratory test |
| Wheeler |
12:45 6-Sep-57 |
NTS, Area 9a |
Balloon |
500 |
197 Tons (200 Tons) |
UCRL |
WD |
Retest of redesigned Lassen device, possible XW-51 air-to-air warhead progenitor |
| Coulomb-B |
20:50 6-Sep-57 |
NTS, Area 3g |
Surface |
0 |
0.3 kt (1-2 Lb, 20 Tons max) |
LASL |
ST |
1-point test for upper limits of safety, similar to Coulomb-A, all-oralloy gas boosted |
| Laplace |
13:00 8-Sep-57 |
NTS, Area 7b |
Balloon |
750 |
1 kt (1.5-2 kt) |
LASL |
WD |
Fleegle device: all-oralloy gun-type weapon |
| Fizeau |
16:45 14-Sep-57 |
NTS, Area 3b |
Tower |
500 |
11 kt (8-10 kt) |
LASL |
WD |
XW-34 test, boosted fission device |
| Newton |
12:50 16-Sep-57 |
NTS, Area 7b |
Balloon |
1500 |
12 kt (50-70 kt) |
LASL |
WD |
Test of XW-31 variant, boosted primary in thermonuclear system mockup |
| Rainier |
16:59.59.5 19-Sep-57 |
NTS, Area 12 |
Tunnel |
-899 |
1.7 kt (-) |
UCRL |
WE |
Deep underground test shot, modified W-25 warhead |
| Whitney |
12:30 23-Sep-57 |
NTS, Area 2 |
Tower |
500 |
19 kt (15 kt) |
UCRL |
WD |
Test of boosted Swan primary in W-27 thermonuclear system mockup |
| Charleston |
13:00 28-Sep-57 |
NTS, Area 9 |
Balloon |
1500 |
12 kt (less than 50-100 kt) |
UCRL |
WD |
Clean tactical 2-stage thermonuclear device, 2nd stage failed to fire |
| Morgan |
13:00 7-Oct-57 |
NTS, Area 9 |
Balloon |
500 |
8 kt (2-10 kt) |
UCRL |
WD |
XW-45X1 test, boosted Swan primary and Flamingo secondary |
N.A.T.O. Observers, Troops in the field near a blast, and Military Officials watching a blast
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