Operation Bedrock

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Series of 1970s US nuclear tests

title: "Operation Bedrock" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["explosions-in-1974", "explosions-in-1975", "1974-in-military-history", "1975-in-military-history", "nevada-test-site-nuclear-explosive-tests"] description: "Series of 1970s US nuclear tests" topic_path: "history" source: "https://en.wikipedia.org/wiki/Operation_Bedrock" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Series of 1970s US nuclear tests ::

::data[format=table title="Infobox nuclear weapons test"]

FieldValue
nameOperation Bedrock
countryUnited States
test_site{{plainlist
period1974–1975
number_of_tests27
test_typeunderground shaft, tunnel
max_yield750 ktTNT
previous_seriesOperation Arbor
next_seriesOperation Anvil (nuclear test)
::

|name = Operation Bedrock |picture = |picture_description = |country = United States |test_site = {{plainlist|

  • NTS Area 12, Rainier Mesa
  • NTS Area 19, 20, Pahute Mesa
  • NTS, Areas 1–4, 6–10, Yucca Flat}} |period = 1974–1975 |number_of_tests = 27 |test_type = underground shaft, tunnel |max_yield = 750 ktTNT |previous_series = Operation Arbor |next_series = Operation Anvil (nuclear test)

The United States's Bedrock nuclear test series followed the Operation Arbor series and preceded the Operation Anvil series.

::data[format=table title="United States' Bedrock 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 | EscabosaEscabosa | Crestlake-Briar - 1Crestlake-Briar | Crestlake-Tansan - 2Crestlake-Tansan | PuyePuye | PortmanteauPortmanteau | PrattPratt | TrumbullTrumbull | StanyanStanyan | EstacaEstaca | Hybla FairHybla Fair | TemescalTemescal | PuddlePuddle | KeelKeel | Portola - 1Portola | Portola-Larkin - 2Portola-Larkin | TelemeTeleme | BilgeBilge | TopgallantTopgallant | CabrilloCabrillo | Dining CarDining Car | EdamEdam | ObarObar | TyboTybo | StiltonStilton | MizzenMizzen | AlvisoAlviso | FuttockFuttock | MastMast | CamembertCamembert | |---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---| | 16:00:00.092 | PST (–8 hrs) | NTS Area U7ac | 1223 m – 638.52 m | underground shaft, weapons development | | | I-131 venting detected, 0 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 14:00:01.2 | PST (–8 hrs) | NTS Area U2dw | 1274 m – 373.68 m | underground shaft, weapons development | | | Venting detected | | Simultaneous, same hole. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 14:00:01.2 | PST (–8 hrs) | NTS Area U2dw | 1274 m – 272 m | underground shaft, weapons development | | | Venting detected, 19 Ci | | Simultaneous, same hole. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 14:00:00.11 | PST (–8 hrs) | NTS Area U3jl | 1188 m – 430.08 m | underground shaft, weapons development | | | I-131 venting detected, 0.000002 Ci | | last1=Garwin |first1=Richard L. |title=Harold M. Agnew: A Biographical Memory |date=2015 |publisher=National Academy of Sciences |page=22 |url=http://biographicalmemoirs.org/pdfs/agnew-harold.pdf |access-date=4 January 2026}} | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 15:00:00.163 | PST (–8 hrs) | NTS Area U2ax | 1313 m – 655.32 m | underground shaft, weapons development | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 14:00:00.08 | PST (–8 hrs) | NTS Area U3hq | 1183 m – 313.96 m | underground shaft, weapons development | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 14:30:00.164 | PST (–8 hrs) | NTS Area U4aa | 1269 m – 262.74 m | underground shaft, weapons development | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 15:05:00.17 | PST (–8 hrs) | NTS Area U2aw | 1275 m – 573.02 m | underground shaft, weapons development | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 17:13:00.118 | PST (–8 hrs) | NTS Area U3ja | 1180 m – 321.05 m | underground shaft, weapons development | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 15:00:00.168 | PST (–8 hrs) | NTS Area U12n.09 | 2227 m – 404.47 m | tunnel, weapon effect | | | Venting detected, 500 Ci | | Test of a new line-of-sight pipe configuration for tunnel testing, basic measurements of blast parameters. The configuration proved to be inadequate for effects testing of warheads. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 15:30:00.164 | PST (–8 hrs) | NTS Area U4ab | 1263 m – 262.74 m | underground shaft, weapons development | | | Venting detected, 2 Ci | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 15:00:00.9 | PST (–8 hrs) | NTS Area U3kg | 1169 m – 183.97 m | underground shaft, safety experiment | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 17:30:00.088 | PST (–8 hrs) | NTS Area U3hu | 1182 m – 304.72 m | underground shaft, weapons development | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 15:30:00.165 | PST (–8 hrs) | NTS Area U10bb | 1285 m – 198.12 m | underground shaft, weapons development | | | Venting detected, 10 Ci | | Simultaneous, same hole. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 15:30:00.16 | PST (–8 hrs) | NTS Area U10bb | 1285 m – 274 m | underground shaft, weapons development | | | Venting detected | | Simultaneous, same hole. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 16:13:00.17 | PST (–8 hrs) | NTS Area U9cl | 1300 m – 304.8 m | underground shaft, weapons development | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 20:10:00.224 | PST (–8 hrs) | NTS Area U3kc | 1179 m – 318.35 m | underground shaft, weapons development | | | Venting detected | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 16:15:00.09 | PST (–8 hrs) | NTS Area U4e | 1245 m – 713.37 m | underground shaft, weapons development | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 16:00:00.169 | PST (–8 hrs) | NTS Area U2dr | 1288 m – 600.46 m | underground shaft, weapons development | | | Venting detected, 11 Ci | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 19:45:00.187 | PST (–8 hrs) | NTS Area U12e.18 | 2238 m – 383.01 m | tunnel, weapon effect | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 14:10:00.17 | PST (–8 hrs) | NTS Area U2dy | 1272 m – 411.48 m | underground shaft, weapons development | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 15:00:00.9 | PST (–8 hrs) | NTS Area U7ag | 1279 m – 568.8 m | underground shaft, weapons development | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 14:00:00.16 | PST (–8 hrs) | NTS Area U20y | 1880 m – 765.05 m | underground shaft, weapons development | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 14:20:00.17 | PST (–8 hrs) | NTS Area U20p | 1667 m – 731.52 m | underground shaft, weapons development | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 14:40:00.106 | PST (–8 hrs) | NTS Area U7ah | 1247 m – 637.18 m | underground shaft, weapons development | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 13:00:00.167 | PST (–8 hrs) | NTS Area U2du | 1261 m – 183 m | underground shaft, safety experiment | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 11:49:00.092 | PST (–8 hrs) | NTS Area U3eh | 1221 m – 186.56 m | underground shaft, safety experiment | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 13:00:00.09 | PST (–8 hrs) | NTS Area U19u | 2068 m – 910.7 m | underground shaft, weapons development | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 12:30:00.161 | PST (–8 hrs) | NTS Area U19q | 2033 m – 1310.64 m | underground shaft, weapons development | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ::

References

References

  1. Mikhailov, V. N.. "Catalog of World Wide Nuclear Testing". Begell-Atom.
  2. "Time Zone Historical Database". iana.com.
  3. (2015). "Harold M. Agnew: A Biographical Memory". [[National_Academy_of_Sciences.
  4. (August 2000). "CMR Nuclear Explosion Database (Revision 3)". SMDC Monitoring Research.
  5. (July 1, 1994). "Official list of underground nuclear explosions". Sandia National Laboratories.
  6. (August 1996). "Radiological Effluents Released from U.S. Continental Tests 1961 Through 1992 (DOE/NV-317 Rev. 1)". DOE Nevada Operations Office.
  7. (September 25, 1998). "Estimates of yield for nuclear tests impacting the groundwater at the Nevada Test Site". Nuclear Science and Technology Division.
  8. (1997). "Estimated exposures and thyroid doses received by the American people from Iodine-131 in fallout following Nevada atmospheric nuclear bomb tests, Chapter 2". National Cancer Institute.
  9. (December 1, 2000). "United States Nuclear Tests: July 1945 through September 1992". Department of Energy, Nevada Operations Office.
  10. (1982). "Operation Argus, 1958". Defense Nuclear Agency, Department of Defense.
  11. (February 1, 1994). "United States nuclear tests, July 1945 to 31 December 1992 (NWD 94-1)". Natural Resources Defense Council.

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explosions-in-1974explosions-in-19751974-in-military-history1975-in-military-historynevada-test-site-nuclear-explosive-tests