Operation Julin

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Series of 1990s US nuclear tests

title: "Operation Julin" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["explosions-in-1991", "explosions-in-1992", "nevada-test-site-nuclear-explosive-tests", "1991-in-military-history", "1992-in-military-history", "1991-in-nevada", "1992-in-nevada", "1991-in-the-environment", "1992-in-the-environment"] description: "Series of 1990s US nuclear tests" topic_path: "history" source: "https://en.wikipedia.org/wiki/Operation_Julin" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Series of 1990s US nuclear tests ::

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

Field	Value
name	Julin
picture	[[File:Julin_Divider.gif
picture_description	Julin Divider (5 kt), the last nuclear weapons test by the United States.
country	United States
test_site	{{plainlist
period	1991–1992
number_of_tests	7
test_type	underground shaft, tunnel
max_yield	100 ktTNT
previous_series	Operation Sculpin
::

|name = Julin |picture = [[File:Julin_Divider.gif|300px]] |picture_description = Julin Divider (5 kt), the last nuclear weapons test by the United States. |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 = 1991–1992 |number_of_tests = 7 |test_type = underground shaft, tunnel |max_yield = 100 ktTNT |previous_series = Operation Sculpin

Operation Julin followed the Operation Sculpin series, and were the last before negotiations began for the Comprehensive Test Ban Treaty.

Nuclear tests

Diamond Fortune

Shot Diamond Fortune was to investigate blast flow field produced by a modern nuclear weapon. The shot was fired in a half-spherical cavity with an 11 m radius, with a 4 m height of burst. The floor was divided into two sections, one covered in base soil and the other in snow simulant.

Hunters Trophy

Shot Hunters Trophy was Lawrence Livermore's last nuclear test and the second to last nuclear test conducted by the United states. Its purpose was to evaluate the radiation hardness of space and high altitude systems, such as optics, sensors and materials for the Strategic Defense Initiative, and the hardness of Sandia detonators. The test consisted of a 850 ft horizontal line of sight (HLOS) pipe and "stub pipes" to simulate different nuclear battlefield environments.

Hunters Trophy included the experiment Hydroplus. The Defense Nuclear Agency (DNA) developed a means of verifying non-standard nuclear tests using ground peak stress and velocity at several ranges from a possible detonation point using computer hydrocodes. These codes required calibration data which was gathered at Hunters Trophy. Further Hydroplus experiments were conducted in shot Distant Zenith of Operation Sculpin.

Divider

Divider was the last nuclear test conducted by the United States.

Cancelled tests

Three tests were being prepared when the moratorium ended further nuclear testing: Icecap, Gabbs and Greenwater.

Icecap was scheduled for spring 1993. It had a planned yield of 20 to and was to be fired at 1557 ft below the surface in Area 9. A diagnostics canister exists at the site, weighing 500000 lb. The canister contains several experiments to be used in the test including THREX (threshold x-ray experiments) which used solid-state detectors to detect photon recoils given off by thin foils, PINEX (pinhole imaging neutron experiment) which used a pinhole to focus radiation onto a fluoroscope, NUEX (neutron experiment) which measured neutron output, and TOMEX (tomographic reconstruction experiment) which imaged the device using a streak camera. These experiments used line of sight (LOS) pipes to channel gamma, x-ray and neutron radiation from the device to them.

Gabbs was planned for early 1993 in Area 2. Unlike Icecap, no diagnostics canister is assembled at the site.

Greenwater, a Lawrence Livermore test, was to be fired in Area 19, and was a test of an x-ray laser system. The test was cancelled 16 July 1992. The Greenwater nuclear device had already been assembled at the time of cancellation, and had to be dismantled.

A fourth test, Mighty Uncle, was planned for 1993. This test was to be a follow-up to Hunters Trophy. Two other tests, Dolomite and Mexia were also planned. Mexia was planned for Area 19.

Both Gabbs and Greenwater were verifiable tests, meaning that under the Threshold Test Ban Treaty, Russia was permitted to have observers and measurement equipment on site to verify that the test yields did not exceed 150 ktTNT.

List of nuclear tests

::data[format=table title="United States' Julin 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 | LubbockLubbock | JunctionJunction | Diamond FortuneDiamond Fortune | VictoriaVictoria | Galena-Green - 3Galena-Green | Galena-Orange - 2Galena-Orange | Galena-Yellow - 1Galena-Yellow | Hunters TrophyHunters Trophy | DividerDivider | |---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---| | 19:12:00.0 | PST (–8 hrs) | NTS Area U3mt | 1213 m–457.2 m | underground shaft, weapons development | | | Venting detected, 0.1 Ci | | | | | | | | | | | | | | 16:30:00.0 | PST (–8 hrs) | NTS Area U19bg | 2013 m–622 m | underground shaft, weapons development | | | | | Treaty verification test. | | | | | | | | | | | | 16:30:00.0 | PST (–8 hrs) | NTS Area U12p.05 | 1656 m–236 m | tunnel, weapon effect | | | Venting detected, 0.2 Ci | | | | | | | | | | | | | | 16:45:00.0 | PST (–8 hrs) | NTS Area U3kv | 1179 m–244 m | underground shaft, weapons development | | | | | | | | | | | | | | | | | 15:00:00.07 | PST (–8 hrs) | NTS Area U9cv | 1269 m + | underground shaft, safety experiment | | | | | Simultaneous, same hole. | | | | | | | | | | | | 15:00:00.07 | PST (–8 hrs) | NTS Area U9cv | 1269 m + | underground shaft, safety experiment | | | | | Simultaneous, same hole. | | | | | | | | | | | | 15:00:00.072 | PST (–8 hrs) | NTS Area U9cv | 1269 m–400 m | underground shaft, weapons development | | | | | Simultaneous, same hole. | | | | | | | | | | | | 17:00:00.078 | PST (–8 hrs) | NTS Area U12n.24 | 1827 m–385.3 m | tunnel, weapon effect | | | Venting detected, 1 Ci | | publisher = Defense Nuclear Agency| pages = | last1 = Gaffney| first1 = Edward S| last2 = Smith| first2 = Eric A| title = Hydroplus Experimental Study of Dry, Saturated and Frozen Geological Materials| url = https://apps.dtic.mil/sti/pdfs/ADA278837.pdf| conference = | access-date = November 6, 2021| archive-date = November 6, 2021| archive-url = https://web.archive.org/web/20211106081417/https://apps.dtic.mil/sti/pdfs/ADA278837.pdf| url-status = live}} | | | | | | | | | | | | 15:04:00.0 | PST (–8 hrs) | NTS Area U3ml | 1208 m–426 m | underground shaft, weapons development | | | Venting detected, 0.1 Ci | | Last U.S. nuclear test; "test to ensure safety of deterrent forces". | | | | | | | | | | | ::

Gallery

References

V. N. Mikhailov. "Catalog of World Wide Nuclear Testing". Begell-Atom, LLC.
McDuff, George Glen. (2018-05-09). "Underground Nuclear Testing".
(19 September 2022). "30 years later, Hunters Trophy participants recall LLNL's final underground nuclear test".
(1993). "Defense Programs: A Sandia weapon review bulletin, Winter 1993.". Sandia National Labs., Albuquerque, NM.; Department of Energy, Washington, DC..
(March 2005). "Nevada Test Site Guide". National Nuclear Security Agency.
Gordon, Michael. (20 July 1992). "'Star Wars' X-Ray Laser Weapon Dies as Its Final Test Is Canceled". The New York Times.
(1993). "Completion Report, Operation JULIN. Part 1, Fiscal year 1992". Department of Energy, Las Vegas, NV. Nevada Operations Office..
"Time Zone Historical Database". iana.com.
"Hydroplus Experimental Study of Dry, Saturated and Frozen Geological Materials". Defense Nuclear Agency.
(August 2000). "CMR Nuclear Explosion Database (Revision 3)". SMDC Monitoring Research.
(July 1, 1994). "Official list of underground nuclear explosions". Sandia National Laboratories.
(August 1996). "Radiological Effluents Released from U.S. Continental Tests 1961 Through 1992 (DOE/NV-317 Rev. 1)". DOE Nevada Operations Office.
(September 25, 1998). "Estimates of yield for nuclear tests impacting the groundwater at the Nevada Test Site". Nuclear Science and Technology Division.
(December 1, 2000). "United States Nuclear Tests: July 1945 through September 1992". Department of Energy, Nevada Operations Office.
(February 1, 1994). "United States nuclear tests, July 1945 to 31 December 1992 (NWD 94-1)". Natural Resources Defense Council.

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