WORLDWIDE TESTING IN APRIL

APRIL 1ST

U.S. tests:  2 
French tests: 2
Total yield:  ~ 29 kilotons
The Details:
1952 -  ‘Able’ was dropped from a B-50 bomber and detonated 790 feet (240m) above Frenchman Flat area 5 at 13:44 GMT with a yield of 1 kiloton from the LANL modified MK-4 bomb as part of a weapons effects test during Operation Tumbler, releasing 140,000 curies of Iodine-131 into the atmosphere .  23rd U.S. test.  Coordinates: 36.7983, -115.9364.
Side Note:  Operation Tumbler was conducted to gather detailed data on blast over pressures and arrival times from airbursts. The first two tests ‘Able’ and ‘Baker’ were both 1 kiloton for convenience in developing scaling laws. 
1960 - ‘Gerboise Blanche’ detonated on the surface of French Algeria at 06:17 GMT with a yield of 10 kilotons from the weapons development device.  2nd French test.  Coordinates: 26.16374, -0.10323.
1966 - ‘Lime’ detonated in a vertical shaft 1,842 feet (561m) beneath Yucca Flat at 18:40 GMT with a yield of < 20 kilotons from the LANL weapons development device.   448th U.S. test.  Coordinates: 37.10265, -116.02081.
1980 - ‘Boros’ detonated in a shaft beneath the rim of Mururoa Atoll at 19:31 GMT with a yield of 18 kilotons, causing a 5.2 magnitude ground shock.  104th French test.  Coordinates: -21.80415, -138.84341.

april1st.jpg

APRIL 2ND

U.S. tests:  1 
French tests: 1 
Total yield:  151 kilotons
The Details:
1977 - ‘Oedipe’ detonated in a shaft beneath the rim of Mururoa Atoll at 13:30 GMT with a yield of 1 kiloton from the weapons development device.  73rd French test.  Coordinates: -21.78424, -138.86878.
1985 - ‘Hermosa’ detonated in a vertical shaft 2,094 feet (638m) beneath Yucca Flat area U7 at 20:00 GMT with a yield of 150 kilotons from the LANL weapons development device during Operation Grenadier, causing a 5.8 magnitude ground shock and creating a 1,279 foot (390m) diameter subsidence crater.   959th U.S. test.  Coordinates: 37.09476, -116.03289.

april2nd.jpg

APRIL 3RD

U.S. tests:  1 
Russian tests: 4 (6 devices)
French tests: 1 
Total yield:  339 kilotons
The Details:
1957 - ‘39’ detonated 3,608 feet (1,100m) above Ground Zero, Semipalatinsk at an unspecified time with a yield of 42 kilotons from the weapons development device after being air-dropped.  36th Russian test.  Coordinates: 50.4, 77.8.
1976 - ‘Patrocle’ detonated in a shaft 2,000 feet (600m) beneath the rim of Mururoa Atoll at 17:07 GMT with a yield of 1 kiloton from the weapons development device.  66th French test.  Coordinates: -21.78944, -138.86149.
1980 - ‘Liptauer’ detonated in a vertical shaft 1,368 feet (417m) beneath Yucca Flat area U2 at 14:00 GMT with a yield of 20 kilotons from the LLNL weapons development device during Operation Tinderbox, causing a 4.8 magnitude ground shock and creating a 557 foot (170m) diameter subsidence crater.  867th U.S. test. Coordinates:  37.14983, -116.08313.
1987 - ‘898’ detonated in a vertical shaft beneath Balapan, Semipalatinsk at 01:17:10:36 GMT with a yield of 140 kilotons from the weapons development device, causing a 6.12 magnitude ground shock.  671st Russian test.  Coordinates: 49.91914, 78.77961.
-- Two seconds later at 01:17:12.32, ‘899’, ‘890’, and ‘891’ detonated simultaneously in the same tunnel within Degelen Mountain, Semipalatinsk with a combined yield of 1 kiloton from the three weapons development devices.  672nd Russian test.  Coordinates: 49.7467, 78.1162.
1988 - ‘940’ detonated in a vertical shaft beneath Balapan, Semipalatinsk at 01:33 GMT with a yield of 135 kilotons from the weapons development device, causing a 5.99 magnitude ground shock.  694th Russian test.  Coordinates: 49.9076, 78.90654.

april3rd.jpg

APRIL 4TH

U.S. tests:  3 
Russian tests: 2 
French tests: 2
Total yield:  ~187 kilotons.
The Details:
1967 - ‘Oakland’ detonated in a vertical shaft 542 feet (165m) beneath Yucca Flat at 14:20 GMT with a yield of <20 kilotons from the LLNL weapons development device during Operation Latchkey, venting 100 curies of Xenon-133 during drill-back operations.  494h U.S. test.  Coordinates: 37.16195, -116.08313.
1968 - ‘Bevel’ detonated in a vertical shaft 789 feet (240m) beneath Yucca Flat at 15:02 GMT with a yield of <20 kilotons from the LANL weapons development device during Operation Crosstie.  540th U.S. test.  Coordinates: 37.0523, -116.02162.
1969 - ‘319’ detonated in a tunnel within Degelen Mountain, Semipalatinsk at 04:57 GMT with a yield of <20 kilotons from the weapons development device.  298th Russian test.  Coordinates: 49.75333, 78.05361.
1979 - ‘Polydore’ detonated beneath the rim of Mururoa Atoll at 18:07 GMT with a yield of 6 kilotons, causing a 4.85 magnitude ground shock.  94th French test.  Coordinates: -21.85000, -138.70200.
1980 - ‘678’ detonated in a vertical shaft beneath Sary-Uzen, Semipalatinsk at 05:32 GMT with a yield of 6 kilotons from the weapons development device, causing a 4.9 magnitude ground shock.  544th Russian test.  Coordinates: 50.00000, 77.82300.
1980 - ‘Pelpos’ detonated in a vertical shaft beneath the rim of Mururoa Atoll at 18:33 GMT with a yield of 5 kilotons, causing a 4.37 magnitude ground shock. 105th French test.  Coordinates: -21.92100, -138.79900.
1991 - ‘Bexar’ detonated in a vertical shaft 2,065 feet (629m) beneath Pahute Mesa at 19:00 GMT with a yield of 140 kilotons from the LANL weapons development device during Operation Sculpin, causing a 5.6 magnitude ground shock and venting Iodine-131 during cement-back operations.  1,042nd U.S. test.  Coordinates: 37.29603, -116.31379.

april4th.jpg

APRIL 5TH

U.S. tests:  6 
Total yield:  ~194.6 kilotons 
The Details:
1962 - ‘Dormouse Prime’ detonated in a vertical shaft 856 feet (261m) beneath Yucca Flat area U3 at 18:00 GMT with a yield of 10.6 kilotons from the LANL weapons development device during Operation Nougat, causing a 4.3 magnitude ground shock, creating a 538 foot (164m) diameter subsidence crater and venting some radiation during drill-back operations.  222nd U.S. test.  Coordinates: 37.04446,-116.02425.
Side Note:  Nuclear weapons tests that include ‘Prime’ in their name indicate a repeat of a previous named test that failed in its objective.  In this case ‘Dormouse Prime’ was a repeat of ‘Dormouse’ conducted on Jan 30, 1962 using the same design device. 
1963 - ‘Ferret Prime’ detonated in a vertical shaft 792 feet (241m) beneath Yucca Flat area U3 at 17:52 GMT with a yield of 7 kilotons from the LANL weapons development device during Operation Storax, creating a 472 foot (144m) diameter subsidence crater.   313th U.S. test.  Coordinates: 37.0373, -116.02468.
Side Note:  A repeat of the 'Ferret' test on February 8, 1963.  
1965 - ‘Kestrel’ detonated in a vertical shaft 1,466 feet (446m) beneath Yucca Flat area U3 at 21:00 GMT with a yield of 7 kilotons from the LANL weapons development device during Operation Whetstone, creating a 449 foot (137m) diameter subsidence crater and venting 230 curies of Xenon and Iodine during drill-back operations.  407th U.S. test.  Coordinates: 37.02576, -116.02351.
1973 - ‘Natoma’ detonated in a vertical shaft 800 feet (243m) beneath Yucca Flat Area U10 at 14:50 GMT with a yield of <20 kilotons from the LLNL weapons development device during Operation Toggle.  721st U.S. test.  Coordinates: 37.17783, -116.05476.
1975 - ‘Dining Car’ detonated in a tunnel 1,256 feet (383m) beneath Rainier Mesa area U12 at 19:45 with a yield of 20 kilotons from the LLNL device as part of a DOD weapons effects test during Operation Bedrock, causing a 4.9 magnitude ground shock.  770th U.S. test.  Coordinates: 37.18787, -116.21476.
1977 - ‘Marsilly’ detonated in a vertical shaft 2,262 feet (689m) beneath Yucca Flat area U2at 15:00 GMT with a yield of 140 kilotons from the LLNL weapons development device during Operation Fulcrum, causing a 5.6 magnitude ground shock, creating a 1,049 foot (320m) diameter subsidence crater and venting 15 curies of radioactive Xenon during drill-back operations.  810th U.S. test.  Coordinates: 37.12019, -116.06315.

april15th.jpg

APRIL 6TH

U.S. tests:  8 
Russian tests: 1 
Total yield:  ~ 220.1 kilotons 
The Details:
1953 - ‘Dixie’ detonated 6,000 feet (1,830m) above Yucca Flat area 7 600 feet (180m) north-east of the designated ground zero at 15:29 GMT with a yield of 11 kilotons from the LANL Mk-5D lithium-hydride boosted device after being dropped by a B-50 bomber during Operation Upshot-Knothole, releasing 1.7 million curies of Iodine-131 which eventually dropped onto Boston, Providence, and Hartford on April 8 after drifting across the U.S.  36th U.S. test.  Coordinates: 37.0847, -116.0189. 
1954 - ‘Koon’ (aka: ‘Morgenstern’) detonated 3 feet (1m) meters above Eninman Island at Bikini Atoll at 18:20 GMT with a yield of 110 kilotons from the weapons development device during Operation Castle, removing a large part of Eninman Island.   46th U.S. test.  Coordinates: 11.49670, 165.36750.   
Side Note:  The yield was far short of the predicted yield of 1 megaton because of a simple design flaw - the neutron flux from the primary pre-heated the secondary which lead to poor compression and failure to ignite the thermonuclear seconday – and ‘Koon’ was essentially a fizzle.  ‘Koon’ was the first thermonuclear device to be designed by LLNL, and was the last weapon design on which Edward Teller directly worked.     
1955 - ‘HA’ (High Altitude) detonated 36,000 feet (11,160m) above Yucca Flat area 1 at 18:00 GMT with a yield of 3 kilotons from the LANL weapons development device as part of a weapons effect test during Operation Teapot, releasing 450,000 curies of Iodine-131 when the parachute retarded device detonated.  59th U.S. test.
1957 - ‘40’ detonated 3,756 feet (1,145m) above Ground Zero, Semipalatinsk at an unspecified time with a yield of 57 kilotons from the weapons development after being air-dropped.  37th Russian test.  Coordinates: 50.4, 77.8. 
1962 - ‘Passaic’ detonated in a vertical shaft 766 feet (233m) beneath Yucca Flat area U9 at 18:00 GMT with a yield of 9 kilotons from the LLNL weapons development device during Operation Nougat, creating a 511 foot (156m) diameter subsidence crater and venting 600 curies of Xenon-133 over a six hour period during drill-back operations.  223rd U.S. test.  Coordinates: 37.11762, -116.04487.
1966 - ‘Stutz’ detonated in a vertical shaft 739 feet (225m) beneath Yucca Flat area U2 at 13:57 GMT with a yield of 5 kilotons from the LLNL weapons development device during Operation Flintlock, causing a 4.45 magnitude ground shock, creating a 419 foot (128m) diameter subsidence crater and venting Xenon-131 from a ventilation line over a period of two days during drill-back operations.  449th U.S. test.  Coordinates: 37.13941, -116.14203.
1967 - ‘Heilman’ detonated in a vertical shaft 501 feet (152m) beneath Yucca Flat area U2 at 15:00 GMT with a yield of <20 kilotons from the LLNL weapons development device during Operation Latchkey, venting 8 curies of Xenon-133 at surface zero for 41 minutes after detonation and later during drill-back operations.  449th U.S. test.  Coordinates: 37.13728, -116.13355.
1985 - ‘Misty Rain’ detonated in a tunnel 1,275 feet (388m) beneath Rainier Mesa area U12 at 23:15 GMT with a yield of 15 kilotons from the LLNL device – a W87 - as part of a DOD weapons effects test during Operation Grenadier, venting 63 curies of Xenon products during controlled venting of the tunnel complex, and was detected off-site.  960th U.S. test.  Coordinates: 37.20078, -116.20805.
Side Note:  'Misty Rain' was a test to determine the radiation hardness of MX reentry vehicles and the vulnerability of satellites to the effects of radiation.   
1990 - ‘Bowie’ detonated in a vertical shaft 700 feet (213m) beneath Yucca Flat area U3 at 17:00 GMT with a yield of 0.1 kilotons (100 tons) from the LANL weapons development device during Operation Aqueduct, causing a 3.1 magnitude ground shock..  1,033rd U.S. test.  Coordinates: 37.06765, -115.99288.

april6th.jpg

APRIL 7TH

U.S. tests:  4
Total yield:  90 kilotons 
The Details:
1951 -  ‘Dog’ detonated atop a 300 foot (91m) tower on Runit (Yvonne) Island at Eniwetok Atoll at 17:33 GMT with a yield  of 81 kilotons from the LANL weapons development device during Operation Greenhouse.  This was the first test of the Greenhouse series at Eniwetok to evaluate  advanced bomb designs and explore thermonuclear concepts.  Dog was a proof test of the Mk-6D bomb using 60 point implosion to improve compression of the core and increase efficiency.  12th  U.S. test.  Coordinates: 11.55234, 162.34648.
Side note: The Mk-6D was the first nuclear weapon stockpiled in large numbers by the U.S. with over 1,100 produced between 1951 and 1955.   It was retired in 1962. 
1966 - ‘Tomato’ detonated in a vertical shaft 742 feet (226m) beneath Yucca Flat at 22:27 GMT with a yield of 6 kilotons from the LANL weapons development device during Operation Flintlock, creating a 439 foot (134m) diameter subsidence crater.  450th U.S. test.  Coordinates: 37.01737, -115.99309.
1967 - ‘Fawn’ detonated in a vertical shaft 889 feet (271m) beneath Yucca Flat at 15:00 GMT with a yield of 1 kiloton from the LANL weapons development device during Operation Latchkey, causing a 3.9 magnitude ground shock, and creating a 508 foot (155m) diameter subsidence crater.  496th U.S. test.  Coordinates: 37.05439, -116.02296.
1988 - ‘Abilene’ detonated in a vertical shaft 804 feet (245m) beneath Yucca Flat at 17:15 GMT with a yield of 2 kilotons from the LANL weapons development device during Operation Touchstone, causing a 4.1 magnitude ground shock and creating a 360 foot (110m) diameter subsidence crater.  1,006th U.S. test.  Coordinates: 37.01311, -116.04519.

april7th.jpg

APRIL 8TH

No nuclear weapons tests were conducted by any country anywhere in the world on this day.

april8th.jpg

APRIL 9TH

U.S. tests: 1
Russian tests: 1
Total Yield:  2.23 kilotons.
The Details:
1955 – ‘Post’ detonated atop a 300 foot (90m) tower on Yucca Flat at 12:30 GMT with a yield of 2 kilotons from the LLNL weapons development device during Operation Teapot, releasing 640,000 curies of Iodine-131 into the atmosphere.   60th U.S. test.  Coordinates: :37.1226, -116.0347.
1971 - ‘369’ detonated in a tunnel within Degelen Mountain, Semipalatinsk at 2:33 GMT with a yield of 0.23 kilotons as part of an industrial applications experiment.  336th Russian test.  Coordinates: 49.83222, 78.03861.

april9th.jpg

APRIL 10TH

U.S. tests: 3 (4 devices)
Russian tests: 4 (5 devices)
French tests: 1
Total Yield:  ~748.101 kilotons.
The Details:
1957 - ‘41’ detonated 6,561 feet (2,000m) above Ground Zero, Semipalatinsk test site at an unspecified time with a yield of 680 kilotons from the thermonuclear weapon development device.  38th Russian test.  Coordinates: 50.42, 77.78.    
1963 - ‘Coypu’ detonated in a vertical shaft 244 feet (74m) beneath Yucca Flat area U3 at 16:01 GMT with a yield of <20 kilotons from the LANL device as part of a safety test during Operation Storax.  314th U.S. test.  Coordinates: 37.04879, -116.03106.
1968 - ‘Noor’ and ‘Throw’ detonated simultaneously in separate vertical shafts 1,252 feet (381m) beneath Yucca Flat area U2 at 14:00 GMT with yields of 20 kilotons and 2 kilotons respectively from the two LLNL weapons development devices during Operation Crosstie, causing a 4.6 magnitude ground shock.    541st U.S. test.
‘Noor’ created a 492 foot (150m) diameter subsidence crater, and vented radioactive Xenon during drill-back operations.  Coordinates: 37.15434, -116.07973. 
‘Throw’ created a 229 foot (70m) diameter subsidence crater.  Coordinates: 37.15667, -116.08323.
1976 - ‘510’ detonated in a tunnel 426 feet (130m) beneath Degelen Mountain, Semipalatinsk at 05:03 GMT with a yield of 0.1 kilotons from the weapons development device, venting unknown radionuclides.  439th Russian test.  Coordinates: 49.75725, 78.04221.
1979 - ‘632’ detonated in a tunnel within Degelen Mountain, Semipalatinsk at an unspecified time with a yield of 0.001 kilotons as part of a safety test.  517th Russian test.  Coordinates: 49.81131, 78.16243.
1980 - ‘679’ and ‘680’ detonated simultaneously in a tunnel within Degelen Mountain, Semipalatinsk at 04:07 GMT with a combined yield of 8 kilotons from the two weapons development devices, causing a 4.98 magnitude ground shock.  545th Russian test.  Coordinates: 49.778, 78.0547.
1981 - ‘Clymene’ detonated in a shaft beneath the lagoon of Mururoa Atoll at 17:57 GMT with a yield of 8 kilotons from the weapons development device , causing a 4.95 magnitude ground shock.  116th French test. Coordinates: -21.82744, -138.8546.
1986 - ‘Mighty Oak’ detonated in a tunnel 1,294 feet (394m) beneath Rainier Mesa at 14:08 GMT with a yield of 20 kilotons from the LLNL device as part of a DOD weapons effects test during Operation Charioteer to determine the lethality of X-rays on Trident and MX warheads, causing a 5.0 magnitude ground shock and venting 36,000 curies of Krypton-85, Iodine-131, and Xenon-133 during controlled releases because of failures in two containment vessels and a mechanical drift protection plug which destroyed about $20 million worth of diagnostic equipment and other military materiel.  976th U.S. test.  Coordinates: 37.21827, -116.18353.

april10th.jpg

APRIL 11TH

U.S. tests: 3
Russian tests: 2
British tests: 1
Total Yield:  188.201 kilotons.
The Details:
1953 - ‘Ray’ detonated atop a 98 foot (30m) tower on Yucca Flat area 4 at 12:44 GMT with a yield of 0.2 kilotons (200 tons) from the LLLN weapons development device during Operation Upshot-Knothole, releasing 28,000 curies of Iodine-131 into the atmosphere is spite of it being a fizzle.  ‘Ray’ was a uranium deuteride device, the 2nd developed by LLNL.  Much like the first, ‘Ruth’ on March 31, it was a failure.  37th U.S. test.  Coordinates: 37.09889, -116.09332.
1963 - ‘Cumberland’ detonated in a vertical shaft 745 feet (227m) beneath Yucca Flat area U2 at 16:03 GMT with a yield of 6 kilotons from the LLNL weapons development device during Operation Storax, creating a 426 foot (130m) diameter subsidence crater and venting 8,500 curies of radioactive Xenon for a period of 7 hours during drill-back operations. 315th US test. Coordinates: 37.15663, -116.07183.  
1972 - ‘Crater’ detonated in a vertical shaft 5,643 feet (1,720m) beneath Turkmenistan at 06:00 GMT with a yield of 15 kilotons as part of a industrial test to extinguish an oil well fire, causing a 4.9 magnitude ground shock.  358th Russian test.  Coordinates: 36.56173, 62.81352.
1978 - ‘Backbeach’ detonated in a vertical shaft 2,204 feet (671m) beneath Pahute Mesa area U19 at 17:45 GMT with a yield of 100 kilotons from the LANL weapons development device during Operation Cresset, causing a 5.5 magnitude ground shock.  833rd U.S. test.  Coordinates: 37.23344, -116.36936.
1978 - ‘Fondutta’ detonated in a vertical shaft 2,076 feet (633m) beneath Pahute Mesa area U19 at 15:30 GMT with a yield of 67 kilotons from the British Chevaline device, causing a 5.5 magnitude ground shock.  29th British test.  Coordinates: 37.29963, -116.32670.
1983 - ‘794’ detonated in a tunnel within Degelen Mountain, Semipalatinsk at an unspecified time with a yield of 0.001 kilotons as part of a safety test.  608th Russian test.  Coordinates: 49.823, 78.033.

april11th.jpg

APRIL 12TH

U.S. tests: 2
Russian tests: 2
Total Yield:  ≈ 26 kilotons.
The Details:
1957 - ‘42’ detonated 3,756 feet (1,145m) above Ground Zero, Semipalatinsk at an unspecified time with a yield of 22 kilotons from the weapons development device after being air-dropped.  39th Russia test.  Coordinates: 50.4, 77.8.
1962 - ‘Hudson’ detonated in a vertical shaft 495 feet (150m) beneath Yucca Flat area U9 at 18:00 GMT with a yield of 1 kiloton from the LLNL weapons development device during Operation Nougat, creating a 19 foot (6m) diameter subsidence crater and venting 500 curies of Xenon during drill-back operations. 224th U.S. test.  Coordinates: 37.12719, -116.04577.
1974 -  ‘Sapello’ detonated in a vertical shaft 593 feet (180m) beneath Yucca Flat area at 15:15 GMT with a yield of <20 kilotons from the LANL weapons development device during Operation Arbor.  745th U.S. test.  Coordinates: 37.01489, -116.04501.
1983 – ‘795’ detonated in a tunnel within Degelen Mountain, Semipalatinsk at 03:41 GMT with a yield of 3 kilotons from the weapons development device, causing a 4.65 magnitude ground shock.  609th Russian test.  Coordinates: 49.791, 78.0807.

april12th.jpg

APRIL 13TH

Russian tests: 1
Total Yield:  <20 kilotons
The Details:
1969 - ‘320’ detonated in a tunnel within Degelen Mountain, Semipalatinsk at an unspecified time with a yield of <20 kilotons from the peaceful applications test.  299th Russian test.  Coordinates:  49.7362, 78.1005.

april13th.jpg

APRIL 14TH

U.S.  tests: 6
Total Yield:  200.15 kilotons.
The Details:
1948 - ‘X-Ray’ detonated atop a 200 foot (60m) tower on the Island Engebi ("Janet") at Eniwetok Atoll at 18:16 GMT with a yield of 37 kilotons from the LANL weapons development device during Operation Sandstone, releasing 140,000 curies of Iodine-131 into the atmosphere.  4th U.S. test.  Coordinates: 11.66276, 162.23785.
Side Note: ‘X-Ray’ was the largest yield device tested to-date.  It used a composite core made of plutonium and uranium that was levitated to improve compression of the pit before initiation of fission.  The use of pit levitation was considered Top Secret until 1980.  
1962 - ‘Platte’ detonated in a tunnel 560 feet (170m) beneath Rainier Mesa area U12at 18:00 GMT with a yield of 1.85 kilotons from the LLNL weapons development device during Operation Nougat, venting  1.9 million curies of various fission products including Iodine-131 and Cesium-141 from the tunnel portal and ground fissures and were detected off-site near Queen City Summit, Nevada .  225th U.S. test.  Coordinates: 37.22198, -116.15832.
1964 - ‘Hook’ detonated in a vertical shaft 662 feet (203m) beneath Yucca Flat area U9 at 14:40 GMT with a yield of 3 kilotons from the LLNL weapons development device during Operation Niblick, creating a 295 foot (90m) diameter subsidence crater and venting 350 curies of Xenon from surface ground zero fissures shortly after detonation then again during drill-back operations.  360th U.S. test.  Coordinates: 37.12887, -116.0307.
1965 - ‘Palanquin’ detonated in a vertical shaft 280 feet (85m) beneath Pahute Mesa area U20 at 13:21 GMT with a yield of 4.3 kilotons from the LLNL peaceful research device as part of a hard rock cratering and radionuclide dispersal experiment during Operation Flintlock, causing a 4.33 magnitude ground shock, creating a 337 foot (103m) crater and releasing 11 million curies of mixed fission products including Iodine-131 into the atmosphere from surface ground zero which was detected off-site.  This was a Plowshares project detonation for the peaceful use of nuclear explosives.   408th U.S. test.  Coordinates: 37.28033, -116.52445.
1966 - ‘Duryea’ detonated in a vertical shaft 1,785 feet (544m) beneath Pahute Mesa area U20 at 14:13 GMT with a yield of 70 kilotons from the LLNL weapons development device during Operation Flintlock, causing a 5.4 magnitude ground shock and releasing 2 curies of Xenon over a period of 1-1/2 days during drill-back operations .  451st U.S. test.  Coordinates: 37.2425, -116.43192.
1983 - ‘Turquoise’ detonated in a vertical shaft 1,749 feet (533m) beneath Yucca Flat area U7 at 19:05 GMT with a yield of 84 kilotons from the LANL weapons development device during Operation Phalanx, causing a 5.7 magnitude ground shock, creating a 557 foot (170m) diameter subsidence crater and venting Xenon-131 during cement-back operations.  921st U.S. test.  Coordinates: 37.07279, -116.04682.

april14th.jpg

APRIL 15TH

U.S. tests: 3
Russian tests: 2
Total yield: 302 kilotons.
The Details:
1965 – ‘Chagan’detonated in a vertical shaft 584 feet (178m) beneath Balapan, Semipalatinsk at 06:00 GMT with a yield of 140 kilotons from the device as part of an industrial earth moving experiment, causing a 5.87 magnitude ground shock and blowing a 1,339 foot (408m) wide, 328 foot (100m) deep hole in the ground. 231st Russian test. Coordinates:  49.9354, 79.008473.
Side Note: ‘Chagan’was the first use of nuclear explosives for industrial purposes conducted by Russia. The resulting large hole filled with water from an adjacent lake. Chagan Lake and the surrounding area remain radioactive today. ‘Chagan’ was similar to the U.S. ‘Sedan’ test which also used a large nuclear device to blow a large hole in the earth at the Nevada Test Site.  Both for peaceful purposes, of course.
1969 - ‘Packard’ detonated in a vertical shaft 810 feet (256m) beneath Yucca Flat area U2 at 19:00 GMT with a yield of 10 kilotons from the LLNL device as part of a weapons effects test during Operation Bowline, creating a 351 foot (107m) diameter subsidence crater and venting 7.2 curies of fission products from surface ground zero for a period of 15 minutes.  582nd U.S. test. Coordinates: 37.14787, -116.06654.
-- Thirty minutes later at 19:30 GMT, ‘Wineskin’detonated in a vertical shaft 1,700 feet (518m) beneath Rainier Mesa with a yield of 40 kilotons from the LLNL weapons development device, causing a 5.3 magnitude ground shock. 583rd U.S. test. Coordinates: 37.20909, -116.22627.
1976 - ‘507’detonated in a tunnel with Degelen Mountain, Semipalatinsk at 04:46 with a yield of 13 kilotons from the weapons development device, causing a 5.18 magnitude ground shock. 436thRussian test. Coordinates:
1981 – ‘Baseball’detonated in a vertical shaft 1,850 feet (564m) beneath Yucca Flat area U7 at 20:25 GMT with a yield of 99 kilotons from the LANL weapons development device during Operation Guardian, causing a 5.7 magnitude ground shock and creating a 492 foot (150m) diameter subsidence crater. 882nd U.S. test. Coordinates: 37.08675, -116.04585.

april15th.jpg

APRIL 16TH

U.S. tests: 2
Russian tests: 2
Total Yield:  490 kilotons.
The Details:
1957 - ‘43’ detonated 6,561 feet (2,000m) above Ground Zero, Semipalatinsk with a yield of 320 kilotons from the weapons development device after being air-dropped.  40th Russian test.  Coordinates: 50.42, 77.78.
1974 - ‘449’ detonated in a vertical shaft beneath Balapan, Semipalatinsk at 05:52 GMT with a yield of 1 kiloton, causing a 4.9 magnitude ground shock.  398th Russian test.  Coordinates: 50.02444, 78.92639.
1980 - ‘Pyramid’ detonated in a vertical shaft 1,900 feet (579m) beneath Yucca Flat area U7 at 20:00 GMT with a yield of 89 kilotons from the LANL weapons development device during Operation Tinderbox, causing a 5.3 magnitude ground shock and creating a 492 foot (190m) ground shock. 868th U.S. test.  Coordinates: 37.10107, -116.0314.
1991 - ‘Montello’ detonated in a vertical shaft 2,105 feet (641m) beneath Pahute Mesa area U20 at 15:30 GMT with a yield of 80 kilotons from the LLNL weapons development device during Operation Sculpin, causing a 5.4 magnitude ground shock.  1,043rd  U.S. test.  Coordinates: 37.24538, -116.44252.

april16th.jpg

APRIL 17TH

U.S. tests: 2
Russian tests: 2 (4 devices) 
Total Yield:  ≈ 92 kilotons.
The Details:
1964 - ‘Bogey’ detonated in a vertical shaft 839 feet (118m) beneath Yucca Flat area U9 at 15:29 GMT with a yield of <20 kilotons from the LLNL weapons development device during Operation Niblick , venting 60 curies of Xenon-133 and Iodine-131 from cable connectors for 38 minutes following detonation and again for 6 hours during drill-back operations.  362nd U.S. test.  Coordinates: 37.11944, -116.03476.
1982 -‘Tenaja’ detonated in a vertical shaft 1,169 feet (356m) beneath Yucca Flat area U3 at 18:00 GMT with a yield of 6 kilotons from the LANL weapons development device during Operation Praetorian, causing a 4.5 magnitude ground shock and creating a 623 foot (190m) diameter subsidence crater.  902nd U.S. test.  Coordinates: 37.01676, -116.01063.
1987 - ‘902’, ‘903’ and ‘904’ detonated simultaneously in the same vertical shaft beneath Balapan, Semipalatinsk at 01:03 GMT with a combined yield of 86 kilotons, causing a 5.92 magnitude ground shock.  673rd Russian test.  Coordinates:  49.87778, 78.66889. 
1987 - Unnumbered #11 detonated in a tunnel within Degelen Mountain, Semipalatinsk at an unspecified time with no yield from the weapons development device.  Coordinates:  49.751, 78.049.

april17th.jpg

APRIL 18TH

U.S. tests: 3
Total Yield:  143 kilotons.
The Details:
1953 - ‘Badger’ detonated atop a 300 foot (90m) tower on Yucca Flat area 2 at 12:35 GMT with a yield of 23 kilotons from the LANL TX-16 weapons development device during Operation Upshot-Knothole, releasing 3.6 million curies of Iodine-131 into the atmosphere.  38thth U.S. test.  Coordinates: 37.1383, -116.1187.  
Side Notes: This was a test of the TX-16 thermonuclear fission primary design.  The test device was named ‘Buzzard’ and used a deuterium gas boosted primary.   The expected yield was 35-40 kiloton but fell short.   The full scale thermonuclear version of this design was actually deployed on a limited scale as an "Emergency Capability" weapon in late 1953 and early 1954.   The full scale version (6-8 megatons) was never tested.
‘Badger’ included Camp Desert Rock V military maneuvers involving 2,167 marines who would attack objectives within a mile of ground zero where various foxholes. bunkers, landing craft, rifles, food and animals were placed prior to detonation, even dummies dressed in marine uniforms. Helicopters would be used to transport 500 observers to the area.  As the marines got to within a mile of ground zero, their radiation equipment registered 30-50 roentgens and the stem of the mushroom cloud bore down on them.  The helicopters stirred up so much dust few could see and pilots reported their radiac meters reading over 50 roentgens.  All beat a hasty retreat.
1968 - ‘Shuffle, detonated in a vertical shaft 1,619 feet (493m) beneath Yucca Flat U10 at 14:05 GMT with a yield of 20 kilotons from the LLNL weapons development device during Operation Crosstie, causing a 5.9 magnitude ground shock and creating a 547 foot (167m) diameter subsidence crater.  542nd U.S. test.  Coordinates: 37.15236, -116.03826.
1987 - ‘Delamar’ detonated in a vertical shaft 1,785 feet (544m) beneath Pahute Mesa area U20 at 13:40 GMT with a yield of 100 kilotons from the LLNL weapons development device during Operation Musketeer, causing a 5.5 magnitude ground shock.  993rd U.S. test.  Coordinates: 37.24798, -116.51013.

april18th.jpg

APRIL 19TH

U.S. tests: 2
Russian tests: 3
French tests: 1
Total Yield:  ≈ 75.4 kilotons.
The Details:
1972 - ‘Longchamps’ detonated in a vertical shaft 1,071 feet (326m) beneath Yucca Flat area U2 at 16:32 GMT with a yield of 8 kilotons from the LLNL weapons development device during Operation Grommet, causing a 4.6 magnitude ground shock and creating a 98 foot (30m) diameter subsidence crater.  696th U.S. test.  Coordinates: 37.12204, -116.08486.
-- Ten minutes later at 16:42 GMT, ‘Jicarilla’ detonated in a vertical shaft 485 feet (148m) beneath Yucca Flat area U2 with a yield of <20 kilotons from the LANL weapons development device.  697th U.S. test.  Coordinates: 37.00661, -116.01734.
1973 - ‘424’ detonated in a vertical shaft beneath Sary-Uzen, Semipalatinsk at 04:32 GMT with a yield of 21 kilotons, causing a 5.36 magnitude ground shock.  380th Russian test.  Coordinates: 49.98400, 78.61400.
1983 - ‘Eurytos’ detonated in a shaft beneath the lagoon of Mururoa Atoll at 18:53 GMT with a yield of 40 kilotons, causing a 5.53 magnitude ground shock.  135th French test.  Coordinates: -21.85264, -138.89405.
1987 - ‘906’ detonated in a vertical shaft 6,610 feet (2,015m) beneath the Perm area of Russia at 04:00 GMT with a yield of 3.2 kilotons as part of an oil stimulation test, causing a 4.5 magnitude ground shock.  674th Russian test.  Coordinates:  60.6, 57.2. 
-- Five minutes later at 04:05 GMT, ‘907’ detonated in an adjacent vertical shaft 6,742 feet (2,055m) deep with a yield of 3.2 kilotons as part of an oil stimulation test code-named ‘Geliy.’  675th Russian test.  Coordinates: 60.8, 57.5.

april19th.jpg

APRIL 20TH

U.S. tests: 2
Russian tests: 2
Total Yield:  85.501 kilotons.
The Details:
1951 – ‘Easy’ detonated atop a 299 foot (91m) tower on the west end of Enjebi (Janet) Island at Eniwetok Atoll at 17:27 GMT with a yield of 47 kilotons from the LANL MK-5D device during Operation Greenhouse.  13th U.S. test.  Coordinates: 11.66543,162.23379 
Side Note: ‘Easy’ was a proof test of the MK-5D using a 92 point lens implosion system and composite plutonium/ORALLOY (Oak Ridge Alloy, aka: enriched uranium) core.  Scale buildings (homes, bunkers, factories) were assembled on Enjebi and adjacent Mujinkarikku Island to determine the effects of a nuclear detonation on them.  The MK-5D design was later used as the fission primary for Ivy Mike, the first thermonuclear device.  
https://www.youtube.com/watch?v=BWzKBlGcnhk
1967 - ‘277’ detonated in a tunnel within Degelen Mountain, Semipalatinsk at 04:08 GMT with a yield of 37 kilotons from the peaceful research device, causing a 5.56 magnitude ground shock.  266th Russian test.  Coordinates: 49.7416, 78.1054.
1972 - ‘399’ detonated in a tunnel within Degelen Mountain, Semipalatinsk at an unspecified time with a yield of 0.001 kilotons as part of a safety test.  359th Russian test.  Coordinates: 49.84352, 78.10513.
1986 - ‘Mogollon’ detonated in a vertical shaft 851 feet (259m) beneath Yucca Flat area U3 at 15:12 GMT with a yield of 1.5 kilotons from the LANL weapons development device during Operation Charioteer, causing a 4.0 magnitude ground shock and creating a 262 foot (80m) diameter subsidence crater.  977th U.S. test.  Coordinates: 37.01164, -116.04679.

april20th.jpg

APRIL 21ST

U.S. tests: 5 (6 devices)
Russian tests: 3
Total Yield:  118.7 kilotons.
The Details:
1962 - ‘Dead’ detonated in a vertical shaft 634 feet (193m) beneath Yucca Flat area U9 at 18:40 GMT with a yield of 3 kilotons from the LLNL weapons development device during Operation Nougat, creating a 255 foot (78m) subsidence crater and venting 40,000 curies of Xenon-133 over a period of 44 hours from the post-shot dill hole during drill-back operations.  226th U.S. test.  Coordinates: 37.11895, -116.03237.
1965 - ‘Gum Drop’ detonated in a tunnel 1,000 feet (304m) beneath Area 16 of the Nevada Test Site at 22:00 GMT with a yield of 20 kilotons from the LLNL device as part of a weapons effects test during Operation Whetstone, causing a 5.0 magnitude ground shock and venting 1,900 curies of Xenon-135 during controlled releases from the tunnel complex and for 66 hours during drill-back operations.  409th U.S. test.  Coordinates: 37.00712, -116.20293.
1966 - ‘255’ detonated in a tunnel within Degelen Mountain, Semipalatinsk at 03:58 GMT with a yield of 22 kilotons as part of a peaceful research test, causing a 5.37 magnitude ground shock.  247th Russian test.  Coordinates: 49.8097, 78.1. 
1967 - ‘Chocolate’ detonated in a vertical shaft 788 feet (240m) beneath Yucca Flat area U3 at 15:09 GMT with a yield of 7 kilotons from the LANL weapons development device during Operation Latchkey, causing a 4.3 magnitude ground shock and creating a 393 foot (120m) diameter subsidence crater.  497th U.S. test.  Coordinates: 37.01928, -116.03818.
1970 - ‘Snubber’ detonated in a vertical shaft 1,127 feet (343m) beneath Yucca Flat area U3 at 14:30 GMT with a yield of 12.7 kilotons from the LANL device as part of a weapons effects test during Operation Mandrel, causing a 4.6 magnitude ground shock and venting 55,000 curies of Iodine-131 from test cables and surface ground zero for a period of 24 hours after detonation which was detected off-site.  641st U.S. test.  Coordinates: 37.05451, -115.98926.
-- Thirty minutes later at 15:00 GMT, ‘Can-Green’ and ‘Can-Red’ detonated simultaneously in separate but adjacent shafts 900 feet (274m) beneath Yucca Flat area U2 with yields of 20 kilotons each from the two LLNL weapons development devices, causing a 4.8 magnitude ground shock and creating 590 foot (180m) and 557 foot (170m) subsidence craters, respectively.   642nd U.S. test.  Coordinates: 37.11236, -116.08281 and 37.11554, -116.08098, respectively.
1976 - ‘511’  detonated in a tunnel within Degelen Mountain, Semipalatinsk at 04:58 GMT with a yield of 7 kilotons from the weapons development device, causing a 4.94 magnitude ground shock.  440th Russian test.  Coordinates: 49.7462, 78.106.
-- Four minutes later at 05:02 GMT, ‘512’ detonated beneath Balapan, Semipalatinsk with a yield of 7 kilotons from the weapons development device, causing 5.12 magnitude ground shock.  441st Russian test.  Coordinates: 49.90155, 78.82874.

april21st.jpg

APRIL 22ND

U.S. tests: 3
Russian tests: 4 (8 devices)
British tests: 1
Total Yield:  200.4 kilotons.
The Details:
1965 - ‘Chenille’ detonated in a vertical shaft 461 feet (140m) beneath Yucca Flat area U9 at 13:39 GMT with a yield of 1 kiloton from the LLNL weapons development device during Operation Whetstone, causing a 3.9 magnitude ground shock, creating a 262 foot (80m) diameter subsidence crater and venting 110 curies of Iodine-131 and Xenon-133 from the emplacement casing shortly after detonation and then for a period of 20 hours during drill-back operations.     410th U.S. detonation.  Coordinates: 37.11137, -116.03136.
1966 - ‘259’ detonated in a vertical shaft 541 feet (165m) beneath Bolshoy Azgir, Kazakhstan at 02:58 GMT with a yield of 1.1 kilotons as part of a cavity formation experiment code-named ‘Galit’ causing a 4.7 magnitude ground shock and venting radionuclides   248th Russian test.  Coordinates: 47.8297, 47.93477.
1978 - ‘573’, ‘574’, and ‘575’ detonated simultaneously in a tunnel within Degelen Mountain, Semipalatinsk at 03:07 GMT with a combined yield of 20 kilotons from the three weapons development devices, causing a 5.35 magnitude ground shock.  483rd Russian test.  Coordinates: 49.7469, 78.1251.
1981 - ‘724’, ‘725’, and ‘726’  detonated simultaneously in a vertical shaft beneath Balapan, Semipalatinsk at 01:17 GMT with a combined yield of 92 kilotons from the three weapons development devices, causing a 5.94 magnitude ground shock.  569th Russian test.  Coordinates: 49.89986, 78.80613.
1983 - ‘Armada’ detonated in a vertical shaft 869 feet (265m) beneath Yucca Flat area U9 at 13:53 GMT with a yield of 1.5 kilotons from the British weapons development device, causing a 4.0 magnitude ground shock.  37th British test.  Coordinates: 37.11144, -116.02319.
1986 - ‘Jefferson’ detonated in a vertical shaft 1,998 feet (609m) beneath Pahute Mesa area U20 at 14:30 GMT with a yield of 80 kilotons from the LLNL weapons development device during Operation Charioteer, causing a 5.4 magnitude ground shock.  978th U.S. detonation.  Coordinates: 37.26406, -116.44109. 
1987 - ‘Presidio’ detonated in a vertical shaft 1,049 feet (319m) beneath Yucca Flat area U6 at 23:00 GMT with a yield of 2.5 kilotons from the LANL weapons development device during Operation Musketeer, causing a 4.2 magnitude ground shock.  994th U.S. detonation.  Coordinates: 36.98311, -116.00531.
1988 - ‘941’ detonated in a tunnel 406 feet (124m) beneath Degelen Mountain, Semipalatinsk at 09:30 GMT with a yield of 2.3 kilotons as part of a weapons effects test, causing a 4.9 magnitude ground shock.  695th Russian test.  Coordinates: 49.7942, 78.1. 

april22nd.jpg

APRIL 23RD

U.S. tests: 4
Total Yield:  8.5 kilotons.
The Details:
1965 - ‘Muscovy’ detonated in a vertical shaft 591 feet (180m) beneath Yucca Flat area U3 at 21:44 GMT with a yield of 600 tons from the LANL weapons development device during Operation Whetstone, causing a 3.7 magnitude ground shock.  411th U.S. test.  Coordinates: 37.01741, -115.99605.
1966 - ‘Fenton’ detonated in a vertical shaft 550 feet (167m) beneath Yucca Flat area U2 at 14:55 GMT with a yield of 1.4 kiloton from the LLNL weapons development device during Operation Flintlock, causing a 3.3 magnitude ground shock and venting 1,700 curies of Iodine-131 and Xenon-133 for a period of 3 minutes from an access shaft immediately after detonation and for 24 days during subsequent drill-back operations.  Xenon was detected as far away as Baker, California.  452nd U.S. test.  Coordinates: 37.16052, -116.08381.
1968 - ‘Scroll’ detonated in a vertical shaft 750 feet (228m) beneath Pahute Mesa area U19 at 17:01 GMT  with a yield of 6 kilotons from the LANL device as part of a Vela Uniform nuclear detection joint verification test during Operation Crosstie, causing a 3.89 magnitude ground shock and venting 18,000 curies of mixed radionuclides including Krypton-87 and 88, Rubidium-88, Iodine-131, 133 and 135, Xenon-133,135,137 and 138, and Cesium -138 from surface ground zero immediately following detonation.  543rd U.S. test.  Coordinates: 37.33767, -116.37647.
1974 - ‘Potrero’ detonated in a vertical shaft 690 feet (210m) beneath Yucca Flat area U2 at 15:13 GMT with a yield of 500 tons from the LLNL weapons development device during Operation Arbor, causing a 3.6 magnitude ground shock.  746th U.S. test.  Coordinates: 37.15999, -116.07736.

april23rd.jpg

APRIL 24TH

U.S. tests: 6 (7 devices)
Russian tests: 1
Total Yield:  75 kilotons.
The Details:
1957 - ‘Project 57 No. 1’ was detonated asymmetrically (to simulate an accidental detonation) on the surface of the Nellis Air Force Range area 13 at 14:27 GMT with ZERO yield from the LANL device as part of a safety test conducted during Project 57.  86th U.S. test.  Coordinates: 37.31935, -115.90608.
Side Notes:  This was a dual purpose test, first to determine the one-point safety of the XW-25 device in case of an accidental detonation, and also a plutonium dispersal test of the air defense warhead which was expected to be widely deployed in large numbers, even within urban population centers.  The 10 mile (16 km) by 16 mile (26 km) block of land was severely contaminated with plutonium.
- Shortly after the detonation, 70 to 80 dogs were placed in cages throughout the area for periods of 4 to 161 days to examine what would happen to them after inhaling plutonium in the dust, then killed and dissected to determine plutonium uptake.  It was determined that 99% of the plutonium was fragmented into particles small enough to be picked up and carried by winds and water in what was termed “resuspension.”
- The area was closed off by two fences; an inner fence surrounding the highly contaminated area around ground zero and an outer fence enclosing the area in which concentrations greater than 10 pCi/g - a fatal human dose - existed.  Plants that were grown in the area had plutonium concentrations of 5.2 to 1,200 pCi/g - as much as a hundred times more than a fatal human dose - in plant stems and in dust coatings on stems and leaves.
- Subsequent experiments using cattle – some pregnant – grazing in the area found concentrations of plutonium in the butchered cattle that suggested plutonium would concentrate in human gonads, bone, liver, and lungs.   Most notably, it was found that pregnant cattle transferred plutonium to their unborn calves.
-  In 1981 the DOE began decontaminating the area and continued until 1992 with hundreds of thousands of cubic yards of soil and debris being removed and buried in a waste facility at the Nevada Test Site.  The total cost of this project exceeded $21,000,000 yet the area remains contaminated.   
1963 - ‘Kootanai’ and ‘Paisano’ detonated simultaneously in separate but adjacent vertical shafts 597 feet (181m) and 186 feet (56m) deep respectively beneath Yucca Flat area U9 at 16:09 GMT  with yields of <20 kilotons each from the two LLNL devices during Operation Storax, venting 410 curies of Iodine-131 and Cesium 138 from surface ground zero test cables immediately following detonation and for a period of four hours during drill-back operations. 
‘Kootanai’ - 316th U.S. test.  Coordinates: 37.12055, -116.03715.
‘Paisano’  -  317th U.S. test.  Coordinates: 37.12048, -116.03704.
1964 - ‘Turf’ detonated in a vertical shaft 1,663 feet (506m) beneath Yucca Flat area U10 at 20:10 GMT with a yield of 38 kilotons from the LLNL weapons development device during Operation Niblick, venting 200 curies of Iodine-131 and Xenon-133 for a period of 33 hours during drill-back operations.  363rd U.S. test.  Coordinates: 37.14982, -116.05609.
1968 -  ‘296’ detonated in a tunnel within Degelen Mountain, Semipalatinsk at 10:35 GMT with a yield of 6.2 kilotons from the weapons development device, causing a 4.91 magnitude ground shock.    281st Russian test.  Coordinates:  49.8452, 78.1032.
1969 - ‘Gourd-Amber’ and ‘Gourd-Brown’ detonated simultaneously in separate but adjoining vertical shafts 595 feet (183m) beneath Yucca Flat area U2 at 13:04 GMT with yields of 800 tons and <20 kilotons respectively from the two LLNL weapons development devices during Operation Bowline, causing a 3.8 magnitude ground shock.   ‘Gourd-Amber’ created a 164 foot (50m) diameter subsidence crater.  594th U.S. test.
‘Gourd-Amber’ coordinates:  37.16393, -116.08061.
‘Gourd-Brown’ coordinates:  37.15998, -116.08186.
1975 -  ‘Edam’ detonated in a vertical shaft 1,350 feet (411m) beneath Yucca Flat area U2 at 14:10 GMT with a yield of 20 kilotons from the LLNL weapons development device during Operation Bedrock, causing a 4.6 magnitude ground shock and creating a 557 foot (170m) diameter subsidence crater.  771st U.S. test.  Coordinates: 37.11569, -116.08811

april24th.jpg

APRIL 25TH

U.S. tests: 6 (7 devices)
Russian tests: 7 (12 devices)
British tests: 1
French tests: 1
Total Yield: ≈7,658.6 kilotons.
The Details:
1953 - ‘Simon’ detonated atop a 300 foot (90m) tower on Yucca Flat area 1 at 12:29 GMT with a yield of 43 kilotons from the LANL TX-17 device (code-named "Simultaneity") during Operation Upshot Knothole, releasing 6.3 million curies of radiation into the atmosphere. 39th U.S. test. Coordinates: 37.053, -116.1036.
1954 - ‘Union’ detonated 13 feet (4m) above the surface of Bikini Atoll lagoon atop a barge anchored off the island of Yurochi (Dog) at 18:10 GMT with a yield of 6,900 kilotons (6.9 megatons) from the LANL weapons development device - much higher than the predicted 3 to 4 megatons - during Operation Castle. Although the barge had been moored in water 160 feet (49 m) deep, the detonation left a crater 3,000 feet (910 m) in diameter and 90 feet (27 m) deep in the bottom of the lagoon. 47th U.S. test. Coordinates: 11.6664, 165.3872. Side Note: ‘Union’ was a prototype EC-14 (Emergency Capability) device using a RACER IV primary. Interestingly, the RACER IV primary was used in the Operation Upshot-Knothole series of tests including the ‘Simon’ test conducted one year to the day earlier. Chuck Hansen, a nuclear weapons researcher, noted that the RACER primary had proven to have inconsistent yields, varying from 23 kilotons to 43 kilotons which may explain the higher than expected yield of ‘Union.’
1962 - ‘Adobe’ detonated 2,900 feet (884m) above Christmas (Kiritimati) Island at 15:46 GMT with a yield of 190 kilotons from the LANL weapons development device (XW-50X1-Y2) after being dropped by a B-52, the first test during Operation Dominic I. 227th U.S. test. Coordinates: 1.59, -157.32.
1966 - ‘Pin Stripe’ detonated in a vertical shaft 970 feet (295m) beneath Frenchman Flat area U1 at 18:38 GMT with a yield of 5 kilotons from the LANL device as part of a weapons effects test during Operation Flintlock, causing a 4.51 magnitude ground shock and venting 210,000
curies of gross fission products from surface ground zero fissures for over 14 hours after detonation that was detected off-site. 453rd U.S. test. 36.8874, -115.94159.
1971 - 370’ detonated in a tunnel within Delegen Mountain, Semipalatinsk at 03:32 GMT with a yield of 90 kilotons from the weapons development device, causing a 6.08 magnitude ground shock. 337th Russian test. Coordinates: 49.7685, 78.0339.
1973 - ‘Angus’ and ‘Velarde’ detonated simultaneously in separate but adjacent vertical shafts beneath Yucca Flat area U3 at 22:25 GMT with yields of 9 kilotons and 8 kilotons respectively from the two LANL weapons development devices during Operation Toggle, causing a 4.7 magnitude ground shock and each venting radionuclides. 722nd U.S. test.
‘Angus’ – Depth of burial: 1,485 feet (452m). Vented Xenon-133 during drill-back operations. Coordinates: 37.00483, -116.0292.
‘Velarde’ – Depth of burial: 909 feet (277m). Created a 492 foot (150m) diameter subsidence crater and vented 250 curies of mixed radioactive effluents including Iodine-131 and Xenon 133 during drill-back and cement-back operations. Coordinates: 36.99367, -116.02173.
1975 - ‘477’ detonated in a vertical shaft beneath Bolshoy Azgir, Kazakhstan at 05:00 GMT with a yield of 350 tons as part of a cavity formation test, causing a 4.7 magnitude ground shock. 420th Russian test. Coordinates: 47.909, 47.912.
1977 - ‘538’ detonated in a tunnel within Delegen Mountain, Semipalatinsk at 04:07 GMT with a yield of 10 kilotons from the weapons development device, causing a 5.07 magnitude ground shock. 459th Russian test. Coordinates: 49.8076, 78.1144.
1978 - ‘Asco’ detonated in a vertical shaft 600 feet (183m) beneath Yucca Flat area U10 at 14:35 GMT with a yield of <20 kilotons from the LLNL device as part of a safety test during Operation Cresset. 835th U.S. test. Coordinates: 37.15452, -116.03563.
1980 - ‘681’ and ‘682’ detonated simultaneously in the same vertical shaft beneath Balapan, Semipalatinsk at 03:57 GMT with a combined yield of 19 kilotons from the two weapons development devices, causing a 5.45 magnitude ground shock. 546th Russian test. Coordinates: 49.97749, 78.75886.
1982 - ‘760’, ‘761’, and ‘762’ detonated simultaneously in the same vertical shaft beneath Balapan, Semipalatinsk at 03:23 GMT with a combined yield of 145 kilotons from the three devices as part of a fundamental science test, causing a 6.03 magnitude ground shock. 589th Russian test. Coordinates: 49.9189, 78.88625.
1982 - ‘Gibne’ detonated in a vertical shaft 1,870 feet (570m) beneath Pahute Mesa area at 18:05 GMT with a yield of 89 kilotons from the British weapons development device, causing a 5.4 magnitude ground shock and venting Xenon-133 during drill-back operations. 36th British test. Coordinates: 37.25584, -116.42236.
1983 - ‘Automedon’ detonated in a shaft beneath the rim of Mururoa Atoll at 17:32 GMT with a yield of 250 tons, causing a 4.25 magnitude ground shock. 136nd French test. Coordinates: -21.87593, -138.85063.
1984 - ‘836’ and ‘837’ detonated simultaneously in the same vertical shaft beneath Balapan, Semipalatinsk at 01:09 GMT with a combined yield of 76 kilotons from the two weapons development devices, causing a 5.9 magnitude ground shock. 636th Russian test. Coordinates: 49.93727, 78.8506.
1985 - ‘879’ and ‘880’ detonated simultaneously in the vertical same shaft beneath Balapan, Semipalatinsk at 00:57 GMT with a combined yield of 74 kilotons from the two weapons development devices, causing a 5.84 magnitude ground shock. 660th Russian test. Coordinates: 49.92667, 78.88083.

This Day in Nuclear Weapons Testing History – April 25.jpg

APRIL 26TH

U.S. tests: 2
French tests: 1
Total Yield: 1,395.5 kilotons
The Details:
1968 - ‘Boxcar’ detonated in a vertical shaft 3,308 feet (1,160m) beneath Pahute Mesa area U20 at 15:00 GMT with a yield of 1,300 kilotons from the LLNL weapons development device during Operation Crosstie, causing a 6.3 magnitude ground shock and creating a 984 foot (300m) subsidence crater. 544th U.S. test. Coordinates: 37.29488, -116.45714.
1973 - ‘Colmor’ detonated in a vertical shaft 806 feet (245m) beneath Yucca Flat area U3 at 15:15 GMT with a yield of 500 tons from the LANL weapons development device during Operation Toggle, causing a 3.6 magnitude ground shock and venting Xenon-133 during cement-back operations. 723rd U.S. test. Coordinates: 37.01214, -116.0207.
-- Two hours later at 17:15 GMT, ‘Starwort’ detonated in a vertical shaft 1,850 feet (563m) beneath Yucca Flat area U2 with a yield of 90 kilotons from the LLNL weapons development device, causing a 5.6 magnitude ground shock, creating a 1,115 foot (351m) diameter subsidence crater and venting 10 curies of Xenon-133 during drill-back operations. 724th U.S. test. Coordinates: 37.12301, -116.05937.
1986 - ‘Hyllos’ detonated in a shaft beneath the rim of Mururoa Atoll at 17:02 GMT with a yield of 5 kilotons, causing a 4.77 magnitude ground shock. 160th French test.
Coordinates: -21.87593, -138.85063.

This Day in Nuclear Weapons Testing History – April 26.jpg

APRIL 27TH

U.S. tests: 4
Russian tests: 1
Total Yield:  511.8 kilotons.  
The Details:
1962 - ‘Aztec’ detonated 2,612 feet (796m) above Christmas Island (Kiritimati) at 16:02 GMT with a yield of 410 kilotons from the LANL weapons development device, a XW50-Y3  used in the MGM-31 Pershing missile, after being dropped by a B-52, during Operation Dominic I.  228th U.S. test.  Coordinates: 1.62, -157.31.
1962 - ‘Black’ detonated in a vertical shaft 714 feet (217m) beneath Yucca Flat area U9 at 18:00 GMT with a yield of 5 kilotons from the LLNL weapons development device during Operation Nougat, creating a 406 foot (124m) diameter subsidence crater and venting 150 curies of Xenon-133 during drill-back operations.  229th U.S. test.  Coordinates: 37.11843, -116.03857.
1967 - ‘Effendi’ detonated in a vertical shaft 790 feet (219m) beneath Yucca Flat area U2 at 14:45 GMT with a yield of 800 tons from the LLNL weapons development device during Operation Latchkey, causing a 3.8 magnitude ground shock and creating a 114 foot (35m) subsidence crater.  498th U.S. test.  Coordinates: 37.13873, -116.06407.
1975 - ‘478’ detonated in a vertical shaft beneath Balapan, Semipalatinsk at 05:36 GMT with a yield of 29 kilotons, causing a 5.6 magnitude ground shock.  421st Russian test.  Coordinates: 49.93750, 78.90361.
1977 - ‘Bulkhead’ detonated in a vertical shaft 1,950 feet (594m) beneath Yucca Flat area U7 at 15:00 GMT with a yield of 67 kilotons from the LANL weapons development device during Operation Fulcrum, causing a 5.4 magnitude ground shock.  811th U.S. test.  Coordinates: 37.09474, -116.02875.

april27th.jpg

APRIL 28TH

U.S. tests: 1
British tests: 1
Total Yield: 3,001.7 kilotons.
The Details:
1958 - ‘Yucca’ detonated beneath a balloon 16.29 miles (26.2 kilometers) above the Pacific Ocean 98 miles (136km) NE of Eniwetok at 02:40 GMT with a yield of 1.7 kilotons from the LANL device, a W-25 warhead, as part of a weapons effects test during Operation Hardtack I. 120th U.S. test. Coordinates: 12.617, 167.025
1958 - ‘Grapple Y’ detonated 7,709 feet (2,350m) above the Christmas Island (Kiritimati) area at 19:05 GMT with a yield of 3,000 kilotons from the device, the 2nd successful British thermonuclear bomb, after being dropped by a British Valiant bomber. This was the largest thermonuclear detonation conducted by the UK. 17th British test. Coordinates: 1.6709, -157.23726.

This Day in Nuclear Weapons Testing History – April 28.jpg

APRIL 29TH

U.S. tests: 2
Total Yield: 15 kilotons.
The Details:
1964 - ‘Pipefish’ detonated in a vertical shaft 859 feet (261m) beneath Yucca Flat area U3 at 20:47 GMT with a yield of 15 kilotons from the LANL weapons development device during Operation Niblick, causing a 4.1 magnitude ground shock, creating a 478 foot (146m) subsidence crater and venting Xenon from surface ground zero. 364th U.S. test. Coordinates: 37.03954, -116.02735.
1966 - ‘Ochre’ detonated in a vertical shaft 413 feet (126m) beneath Yucca Flat area U3 at 13:33 GMT with a yield of <20 kilotons from the LANL device as part of a safety test during Operation Flintlock. 454th U.S. test. Coordinates: 37.04364, -116.02323

This Day in Nuclear Weapons Testing History – April 29.jpg

APRIL 30TH

U.S. tests: 7
French tests: 1
Total Yield: ≈292 kilotons.
The Details:
1948 - ‘Yoke’ detonated atop a 200 foot (60m) tower on Aomon Island ("Sally") at Eniwetok Atoll at 18:08 GMT with a yield of 49 kilotons from the LANL MK-3 device during Operation Sandstone, releasing 1.3 million curies of Iodine-131 into the atmosphere. 5th U.S. test. Coordinates: 11.61569, 162.3194.
Side Note: The MK-3 used a levitated pit to improve compression of the mass to increase its yield. ‘Yoke’ was the highest yield device yet tested, a record it kept until 1951. Despite its high yield, it was regarded as an inefficient device. The pit was made of ORALLOY, 11 pounds (5kg) of highly-enriched Uranium 235.
1969 - ‘Thistle’ and ‘Blenton’ detonated simultaneously beneath Yucca Flat area U7 in separate but adjacent vertical shafts at 17:00 GMT with yields of 38 and 51 kilotons respectively from the two LANL weapons development devices during Operation Bowline, causing a 5.3 magnitude ground shock with ‘Blenton’ venting Xenon-138 from surface ground zero fissures for a period of 19 hours.
‘Thistle’ 595th U.S. test. Coordinates 37.09023, -116.00651. Depth of burial: 1,838 feet (560m)
‘Blenton’ 596th U.S. test. Coordinates: 37.08145, -116.01481. Depth of burial: 1,829 feet (557m)
1975 - ‘Obar’ detonated in a vertical shaft 1,866 feet (568m) beneath Yucca Flat area U7 at 15:00 GMT with a yield of 38 kilotons from the LANL weapons development device during Operation Bedrock, causing a 5.2 magnitude ground shock. 772nd U.S. test. Coordinates: 37.10881, -116.02967.
1981 - ‘Vide’ detonated in a vertical shaft 1,060 feet (323m) beneath Yucca Flat at 14:35 GMT with a yield of <20 kilotons from the LLNL weapons development device during Operation Guardian, venting Tritium, Krypton-85, Xenon-133 and Cesium-137 during gas sampling operations. 885th U.S. test. Coordinates: 37.17731, -116.08567.
1985 - ‘Cercyon’ detonated in a shaft beneath the rim of Mururoa Atoll at 17:29 GMT with a yield of 13 kilotons, causing a 5.12 magnitude ground shock. 152nd French test. Coordinates: -21.86854, -138.92079.
1987 - ‘Hardin’ detonated in a vertical shaft 2,051 feet (625m) beneath Pahute Mesa area U20 at 13:30 GMT with a yield of 100 kilotons from the LLNL weapons development device during Operation Musketeer, causing a 5.5 magnitude ground shock and venting Tritium, Krypton-85 and Cesium-137 during gas sampling operations. 995th U.S. test. Coordinates: 37.23299, -116.42401.
1992 – ‘Diamond Fortune’ detonated in a tunnel 771 feet (236m) beneath Rainier Mesa area U12 at 16:30 GMT with a yield of 3 kilotons from the LANL device as part of a weapons effects test during Operation Julin, venting Iodine-131 and Xenon-133 during tunnel ventilation operations. 1,050th U.S. test. Coordinates: 37.23413, -116.15823.

This Day in Nuclear Weapons Testing History – April 30.jpg