Designations Of U.S. Nuclear Weapons

Copyright © 2001-2003 Andreas Parsch

1 Designation System

2 List of Weapons

3 Sources

1 Designation System

All U.S. nuclear weapons (missile warheads, free-fall bombs, artillery shells, etc.) are numbered in a single, consecutive series. The numbers are assigned by the organization controlling the design and manufacture of nuclear weapons. From 1946 to 1974, this was the Atomic Energy Commission (AEC). In 1974, the AEC was abolished and its tasks being taken over by the newly formed Energy Research and Development Administration (ERDA). In 1977, the Department of Energy (DOE) was founded and took over, among many other things, the responsibility for nuclear weapons.

When designating nuclear weapons, a variety of prefixes and suffixes are used with the numbers. However, I don't have any official, first-hand source describing or regulating their use. The following prefixes were used at least once:

• XW - Warhead in the development and test phase
• W - Warhead (production)
• Mark (MK, Mk) - Bomb (until 1968)
• B - Bomb (after 1968)
• TX - "Test Experimental" (prototype bomb or warhead)
• EC - "Emergency Capability" (bomb prototype design stockpiled in very limited numbers)
• S - Artillery shell (rarely used)
• BA - "Basic Assembly" (used only for bombs specially adapted to the B-58's pod)

The first four designs used roman numerals, but this was soon changed to arabic numerals with the MK-IV/MK-4. A dash is usually written between the prefix and the number. In newer references, however, the dash is frequently omitted. Especially the reference to bombs as Bn instead of B-n is quite common, presumably to avoid confusion with US Air Force bomber designations. The warhead (i.e. the nuclear package) of a free-fall bomb always retained its W designation, using the same number as the bomb itself. E.g. the nuclear components of the MK-28 bomb were known as W-28 (in the strictest sense, the MK nomenclature applied only to the non-nuclear bomb components).

Suffixes are used to designate variants of a weapon. The basic suffix is a "Mod" designator. This is used in the same way as in the US Navy's MARK/MOD Nomenclature System, i.e. the first version is designated "Mod 0", followed by "Mod 1", etc. The Mod suffix is often abbreviated to a dash and a number, e.g. B61-11 or W80-1. Different yield options for a weapon can be indicated by a Yn (n = 1, 2, ...) designator immediately behind the number. Of course, Y and Mod suffixes can be combined, as in W-39Y1 Mod 2. Modifications of bomb and warhead prototypes were often indicated by a -Xn (n = 1, 2, ...) suffix, as in TX-7-X1. If an -Xn design was put into production, the -Xn usually became a Mod number (e.g. TX-7-X1 became MK-7 Mod 1).

2 List of Weapons

The list includes every nuclear weapon which was ever assigned a number in the AEC/DOE series. Warheads are always listed as W-n, but bombs are generally shown with the most "common" prefix. All warheads had XW or TX designations when the number was first assigned. Similarly, most bombs started as TX designs before being designated as MK, B or EC.

For each weapon, the developing laboratory (LANL = Los Alamos National Laboratory, LLNL = Lawrence Livermore National Laboratory), the approximate yield(s) and the delivery platforms (carrier aircraft for bombs, missiles for warheads) are listed. Brackets indicate cancelled bombs, warheads and platform/warhead combinations.

Most rockets and missile designations are linked to the corresponding page in the Directory of U.S. Military Rockets and Missiles, which includes detailed information about the weapon.

Number	Laboratory	Yield	Platforms	Remarks
MK-I	LANL	15 kT	B-29 Superfortress	"Little Boy" (dropped on Hiroshima) was a MK-I type bomb
[MK-II]	LANL			Design similar to "Fat Man"; not developed
MK-III	LANL	18 kT - 49 kT	B-29 Superfortress B-50A/D Superfortress	"Fat Man" (dropped on Nagasaki) was a MK-III type bomb
MK-IV/MK-4 [W-4]	LANL	1 kT - 31 kT	MK-4 Bomb: B-29 Superfortress B-36 Peacemaker B-50A/D Superfortress AJ, A-2 Savage W-4 Warhead:   [B-62, SM-62 Snark]   [B-64, SM-64 Navaho]	Derived from MK-III Mod 1; W-4 missile warhead cancelled in favour of W-13
MK-5 W-5	LANL	11 kT - 47 kT	MK-5 Bomb: B-29 Superfortress B-36 Peacemaker B-45A Tornado B-47A/B/E Stratojet B-50A/D Superfortress B-66 Destroyer AJ, A-2 Savage A3D-1/2, A-3A/B Skywarrior W-5 Warhead: B-61, TM-61A/C, MGM-1C Matador SSM-N-8a, RGM-6B Regulus   [B-63, GAM-63 Rascal]   [SSM-N-2 Triton]   [SSM-N-6 Rigel]   [SSM-A-16 Hermes A-3B]	XW-5 for GAM-63 was cancelled in favour of W-27
MK-6	LANL	8 kT - 160 kT	B-29 Superfortress B-36 Peacemaker B-47A/B/E Stratojet B-50A/D Superfortress B-66 Destroyer AJ, A-2 Savage A3D-1, A-3A Skywarrior	Improved MK-4; some retired MK-6 bombs were converted into "Project A" ADM (ADM-A)
MK-7 W-7	LANL	MK-7: 8 kT - 61 kT W-7: 90 T, 2 - 40 kT	MK-7 Bomb: B-45A Tornado B-57B Intruder F-84E/F/G Thunderjet/Thunderstreak F-100D/F Super Sabre F-101A/C Voodoo AD-4B Skyraider AJ, A-2 Savage A3D-1, A-3A Skywarrior A4D-2/5, A-4B/C/E/J/M Skyhawk FJ-4B, AF-1E Fury F2H-2B Banshee F3H-2N, F-3C Demon F9F-8B, AF-9J Cougar W-7 Warhead: 30.5" Rocket MK 1 MOD 0 BOAR SSM-A-17, M2, MGM-5A/B Corporal M31/M50, MGR-1A/B/C Honest John   "Project B" ADM (ADM-B) MK 90 Betty ASW Bomb   [GAM-67 Crossbow]   [SSM-A-13 Hermes A-2]   [SAM-A-25, M6, MIM-14 Nike Hercules]	MK-7 was nicknamed "Thor"; XW-7 for GAM-67 and MIM-14 was cancelled in favour of W-31
MK-8 [W-8]	LANL	25 kT - 30 kT	MK-8 Bomb: B-45A Tornado AD-4B Skyraider AJ, A-2 Savage A3D-1, A-3A Skywarrior A4D-2/5, A-4B/C/E/J/M Skyhawk F2H-2B Banshee F3H-2N, F-3C Demon W-8 Warhead:   [SSM-N-8, RGM-6 Regulus]	MK-8 was nicknamed "Elsie" (for "LC": Light Case); replaced by MK-11
W-9	LANL	15 kT	T-124 280 mm Artillery Shell T-4 ADM
[TX-10] [W-10]	LANL	12 kT - 15 kT	W-10 Warhead:   [KGW-1 Loon]	TX-10 was to be an airburst derivative of the MK-8
TX-11 (MK-91)	LANL	30 kT (?)	AD-4B/7, A-1J Skyraider AJ, A-2 Savage A3D-1, A-3A Skywarrior A4D-2/5, A-4B/C/E/J/M Skyhawk F2H-2B Banshee F3H-2N, F-3C Demon	Improved MK-8; MK-11 production version was known as MK-91 Mod 0 bomb
MK-12 [W-12]	LANL	12 kT, 14 kT	MK-12 Bomb: F-86F/H Sabre AD-7, A-1J Skyraider AJ, A-2 Savage A3D-1, A-3A Skywarrior A4D-2/5, A-4B/C/E/J/M Skyhawk FJ-4B, AF-1E Fury F2H-2B Banshee F3H-2N, F-3C Demon F9F-8B, AF-9J Cougar W-12 Warhead:   [SAM-N-6, IM-70, RIM-8 Talos]   [30.5" Rocket MK 1 MOD 0 BOAR]	MK-12 was nicknamed "Brok"; W-12 was cancelled in favour of W-7 (BOAR) and W-30 (Talos)
[TX-13] [W-13]	LANL	32 kT	W-13 Warhead:   [B-62, SM-62 Snark]   [B-64, SM-64 Navaho]   [SSM-A-14, M8, PGM-11 Redstone]	W-13 was cancelled in favour of W-15 and later W-39
EC-14	LANL	5 MT - 7 MT	B-36 Peacemaker
MK-15 [W-15]	LANL	1.7 MT, 3.4 MT	MK-15 Bomb: B-36 Peacemaker B-47B/E Stratojet B-52 Stratofortress A3D-1, A-3A Skywarrior W-15 Warhead:   [B-62, SM-62 Snark]   [B-64, SM-64 Navaho]   [SSM-A-14, M8, PGM-11 Redstone]	W-15 was cancelled in favour of W-39
[TX-16]	LANL	6 MT - 8 MT
MK-17	LANL	15 MT - 20 MT	B-36 Peacemaker
MK-18	LANL	500 kT	B-36 Peacemaker B-47A/B/E Stratojet A3D-1, A-3A Skywarrior
S-19	LANL	15 kT	T-315 280 mm Artillery Shell
[TX-20]	LANL			Proposed high-yield derivative of MK-13
MK-21 [W-21]	LANL	4 MT - 5 MT	MK-21 Bomb: B-36 Peacemaker B-47B/E Stratojet B-52 Stratofortress W-21 Warhead:   [B-64, SM-64 Navaho]	Later converted to MK-36
[TX-22]	LLNL			Design cancelled after preliminary test failure
S-23	LANL	15 kT - 20 kT	16" Shipborne Gun Shell
MK-24	LANL	15 MT - 20 MT	B-36 Peacemaker	Very similar to MK-17
W-25	LANL	1 kT - 2 kT	MB-1, AIR-2A Genie   [M51, MGR-3 Little John]   ["Project C" ADM (ADM-C)]
[TX-26]	LANL			Cancelled derivative of MK-21
MK-27 W-27	LLNL	2 MT	MK-27 Bomb: AJ, A-2 Savage A3D-1/2, A-3A/B Skywarrior A3J-1, A-5A Vigilante W-27 Warhead: SSM-N-8a, RGM-6B Regulus   [B-61, TM-61, MGM-1 Matador]   [B-63, GAM-63 Rascal]   [SSM-N-2 Triton]   [SSM-N-9, RGM-15 Regulus II]
MK-28 W-28	LANL	MK-28: 70 kT (Y1), 350 kT (Y2), 1.1 MT (Y3), 1.45 MT (Y5) W-28: 11 kT - 1.1 MT	MK-28 Bomb: B-47B/E Stratojet B-52 Stratofortress B-66 Destroyer F-100D/F Super Sabre F-101A/C Voodoo F-104C/G Starfighter F-105 Thunderchief F/FB-111 Aardvark F-4C/D/E Phantom II A3D-1/2, A-3A/B Skywarrior A4D-2/5, A-4B/C/E/J/M Skyhawk A3J-1, A-5A Vigilante A2F, A-6 Intruder A-7 Corsair II FJ-4B, AF-1E Fury W-28 Warhead: TM-76A/B, MGM/CGM-13A/B Mace GAM-77/A, AGM-28A/B Hound Dog
[W-29]	LANL		[B-64, SM-64 Navaho]   [SSM-A-14, M8, PGM-11 Redstone]	Modified W-15; cancelled in favour of W-39
W-30	LANL	0.5 kT, 2 kT	SAM-N-6bW/bW1/c1, RIM-8B/D/E Talos XM113 TADM   [F-99, IM-99, CIM-10 Bomarc]   [AIM-68 Big Q]	W-30/Bomarc cancelled in favour of W-40
W-31	LANL	2 kT, 20 kT, 40 kT (MGR-1) 1 kT - 2 kT, 30 kT - 40 kT (MIM-14) 1 kT - 40 kT (ADM)	M31/M50, MGR-1A/B/C Honest John (Y3) SAM-A-25, M6, MIM-14A/B/C Nike Hercules (Y1, Y2)   ADM   [GAM-67 Crossbow]
[S-32]	LANL		[T-332 240 mm Artillery Shell]	Cancelled in favour of W-48
W-33	LANL	5 kT - 40 kT	M422 8" Artillery Shell
W-34	LANL	10 kT - 15 kT	MK 101 Lulu Depth Bomb MK 105 Hotpoint Bomb MK 45 ASTOR Torpedo
[W-35]	LANL	1.75 MT	[SM-65D/E/F, CGM/HGM-16D/E/F Atlas]   [SM-68, HGM-25A Titan]   [SM-75, PGM-17 Thor]   [SM-78, PGM-19 Jupiter]	Cancelled in favour of W-38 (Atlas E/F, Titan) and W-49 (Atlas D, Thor, Jupiter)
MK-36	LANL	10 MT	B-36 Peacemaker B-47B/E Stratojet B-52 Stratofortress
[W-37]	LANL		[SAM-A-25, M6, MIM-14 Nike Hercules]	XW-37 was redesignated XW-31Y2
W-38	LLNL	4.5 MT	SM-65E/F, CGM-16E/F Atlas SM-68, HGM-25A Titan
MK-39 W-39	LLNL	3 MT - 4 MT	MK-39 Bomb: B-36 Peacemaker B-47B/E Stratojet B-52 Stratofortress B-58 Hustler (BA-39 in bomb pod) A3D-1, A-3A Skywarrior W-39 Warhead: B-62, SM-62A Snark SSM-A-14, M8, PGM-11A Redstone   [B-64, SM-64 Navaho]
W-40	LANL	7 kT - 10 kT (CIM-10) 1.7 kT, 10 kT (MGM-18)	F-99, IM-99A/B, CIM-10A/B Bomarc SSM-A-12, M4, MGM-18A Lacrosse   [ASM-N-8 Corvus]
MK-41 [W-41]	LLNL	25 MT	MK-41 Bomb: B-47B/E Stratojet B-52 Stratofortress
[W-42]	LLNL		[GAR-9, AIM-47 Falcon]   [AAM-N-9 Sparrow X]   [AAM-N-10 Eagle]   [SAM-A-18, M3, MIM-23 Hawk]	Cancelled in favour of W-54
MK-43	LANL	70 kT, 500 kT, 1 MT	B-47B/E Stratojet B-52 Stratofortress B-57B Intruder B-58 Hustler F-100D/F Super Sabre F-101A/C Voodoo F-104C/G Starfighter F-105 Thunderchief F/FB-111 Aardvark F-4C/D/E Phantom II AD-6, A-1H Skyraider A3D-1/2, A-3A/B Skywarrior A4D-2/5, A-4B/C/E/J/M Skyhawk A3J-1, A-5A Vigilante A2F, A-6 Intruder A-7 Corsair II FJ-4B, AF-1E Fury
W-44	LANL	10 kT	RUR-5A Asroc
W-45	LLNL	500 T - 15 kT	GAM-83B, AGM-12D Bullpup (Y3, Y4) SAM-N-7, RIM-2D Terrier (Y1, Y4) M51, MGR-3A Little John (Y1, Y2, Y4)   MADM (Y1, Y2, Y3, Y4)
[TX-46] [W-46]	LANL	10 MT	W-46 Warhead:   [SSM-A-14, M8, PGM-11 Redstone]	Cancelled in favour of MK-53/W-53
W-47	LLNL	600 kT (Y1), 1.2 MT (Y2)	UGM-27A/B Polaris A1/A2
W-48	LLNL	70 T - 100 T	M454 155 mm Artillery Shell
W-49	LANL	1.45 MT	SM-65D, PGM-16D Atlas SM-75, PGM-17A Thor SM-78, PGM-19A Jupiter
W-50	LANL	60 kT (Y1), 200 kT (Y2), 400 kT (Y3)	M14, MGM-31A/B Pershing XLIM-49A Nike Zeus B   [HSM-80A, LGM-30A Minuteman]   [ASM-N-x Hopi]
[W-51]	LLNL	22 T	[GAR-11, AIM-26 Falcon]   [M388 Projectile for M28/M29 Davy Crockett]	XW-51 was transferred to LANL and redesignated XW-54
W-52	LANL	200 kT	SSM-A-27, M15, MGM-29A Sergeant
MK-53 W-53	LANL	9 MT - 10 MT	MK-53 Bomb: B-47B/E Stratojet B-52 Stratofortress B-58 Hustler (BA-53Y1 in BLU-2/B pod) W-53 Warhead: SM-68B, LGM-25C Titan II
W-54	LANL	250 T (GAR-11) 10 T, 20 T (M388) 10 T - 1 kT (SADM)	GAR-11, AIM-26A Falcon M388 Projectile for M28/M29 Davy Crockett M129/M159 SADM	SADM (Special Atomic Demolition Munition) was also known as B-54
W-55	LLNL	250 kT	UUM-44A Subroc	Some sources quote a low kiloton yield (1 - 5 kT)
W-56	LLNL	2 MT	HSM-80B/F, LGM-30B/F Minuteman I/II (Mk.11 RV)
MK-57	LANL	5 kT - 20 kT	B-52 Stratofortress F-100D/F Super Sabre F-104C/G Starfighter F-105 Thunderchief F/FB-111 Aardvark F-4C/D/E Phantom II A3D-2, A-3B Skywarrior A4D-2/5, A-4B/C/E/J/M Skyhawk A3J-1, A-5A Vigilante A2F, A-6 Intruder A-7 Corsair II F/A-18 Hornet P2V-5F/7, P-2E/H Neptune P-3 Orion S2F-1/2/3/3S, S-2A/C/D/E Tracker S-3 Viking SH-3D/H Sea King
W-58	LLNL	200 kT	UGM-27C Polaris A3
W-59	LANL	800 kT, 1.2 MT	HSM-80A, LGM-30A Minuteman I (Mk.5 RV)   [GAM-87, AGM-48 Skybolt]
[W-60]	LLNL	(low)	[SAM-N-8, RIM-50 Typhon LR]
B-61	LANL	10 kT - 300 kT (Mod 0/1/7) 10 kT - 150 kT (Mod 2/5) 300 T, 1.5 kT, 60 kT, 170 kT (Mod 3) 300 T, 1.5 kT, 10 kT, 45 kT (Mod 4) 300 T, 5 kT, 10 kT, 80 kT (Mod 10) 1.7 kT - 300 kT (Mod 11)	B-52 Stratofortress B-1B Lancer B-2A Spirit F-100D/F Super Sabre F-104C/G Starfighter F-105 Thunderchief F/FB-111 Aardvark F-117A Nighthawk F-4C/D/E Phantom II F-15E Eagle F-16 Fighting Falcon A4D-2/5, A-4B/C/E/J/M Skyhawk A2F, A-6 Intruder A-7 Corsair II F/A-18 Hornet	Also known as MK/B-61
W-62	LLNL	170 kT	LGM-30G Minuteman III (Mk.12 RV)   [UGM-73 Poseidon C3]	W-62/Poseidon was cancelled in favour of W-68
[W-63]	LLNL		[MGM-52 Lance]	Enhanced Radiation ("Neutron Bomb") warhead; cancelled in favour of W-70
[W-64]	LANL		[MGM-52 Lance]	Enhanced Radiation ("Neutron Bomb") warhead; cancelled in favour of W-63
[W-65]	LLNL		[LIM-100(?) Sprint]	Enhanced Radiation ("Neutron Bomb") warhead; cancelled in favour of W-66
W-66	LANL	1 kT	LIM-100(?) Sprint	Enhanced Radiation ("Neutron Bomb") warhead
[W-67]	LANL	150 kT	[LGM-30G Minuteman III]   [UGM-73 Poseidon]	Cancelled in favour of W-62 (Minuteman) and W-68 (Poseidon)
W-68	LLNL	40 kT - 50 kT	UGM-73A Poseidon C3
W-69	LANL	170 kT - 200 kT	AGM-69A SRAM
W-70	LLNL	1 kT - 100 kT (Mod 0/1/2) 1 kT (Mod 3)	MGM-52C Lance	Mod 3 is the Enhanced Radiation ("Neutron Bomb") version
W-71	LLNL	5 MT	LIM-49A Spartan
W-72	LANL	625 T	AGM-62 Walleye MK 6 MOD 0	Modified from retired W-54 warheads
[W-73]	LANL		[ASM-N-11, AGM-53A Condor]	Derived from MK/B-61
[W-74]	LANL	> 100 T	[155 mm Artillery Shell]	Cancelled in favour of W-82
[W-75]	LLNL	> 100 T	[8" Artillery Shell]	Similar to W-74; cancelled in favour of W-79
W-76	LANL	90 kT - 100 kT	UGM-96A Trident
[B-77]	LLNL	1 MT		Cancelled in favour of B-83
W-78	LANL	335 kT - 350 kT	LGM-30G Minuteman III (Mk.12A RV)	Derived from W-50
W-79	LLNL	100 T - 1.1 kT (Mod 0) 100 T - 0.8 kT (Mod 1)	XM753 8" Artillery Shell	Mod 1 has Enhanced Radiation ("Neutron Bomb") option
W-80	LANL	5 kT - 200 kT (W-80-0) 5 kT - 150 kT (W-80-1)	BGM/RGM/UGM-109A Tomahawk (W-80-0) AGM-86B ALCM (W-80-1) AGM-129A ACM (W-80-1)	Derived from MK/B-61
[W-81]	LANL	3 kT - 4 kT	[RIM-67 Standard SM-2 (ER)]	Variant of MK/B-61
W-82	LLNL	< 2 kT	XM785 155 mm Artillery Shell	Similar to W-79
B-83	LLNL	1.2 MT	B-52 Stratofortress B-1B Lancer B-2A Spirit FB-111A Aardvark
W-84	LLNL	200 T - 150 kT	BGM-109G Gryphon	Derived from MK/B-61 Mod 3/4
W-85	LANL	5 kT - 50 kT	MGM-31C Pershing II	Derived from MK/B-61 Mod 3/4; was recycled after retirement into B-61 Mod 10
[W-86]	LANL		[MGM-31C Pershing II]	Earth-penetrating warhead
W-87	LLNL	300 kT (W-87-0) 475 kT (W-87-1)	LGM-118A Peacekeeper (W-87-0)   [MGM-134 Midgetman (W-87-1)]
W-88	LANL	475 kT	UGM-133A Trident II (Mk.5 RV)
[W-89]	LLNL	200 kT	[RUM/UUM-125A Sea Lance ASWSOW]   [AGM-131A SRAM II]
[B-90]	LANL	200 kT		Depth/Strike bomb
[W-91]	LANL	10 kT, 100 kT	[AGM-131B SRAM-T]

3 Sources

In no particular order:

[1] Chuck Hansen: "Swords of Armageddon", 1995
[2] James N. Gibson: "Nuclear Weapons of the United States", Schiffer Publishing Ltd, 1996
[3] Stephen I. Schwartz (ed.): "Atomic Audit: The Costs and Consequences of U.S. Nuclear Weapons Since 1940", Brookings Institution Press, 1998

Comments and corrections to: Andreas Parsch

Back to Home page

---

Last Updated: 12 November 2003