Drawing Back the Curtain of Secrecy, Section V.C

C. FISSION WEAPONS

1. Fact that development of atomic warheads for guided missiles or artillery is underway - Any elaboration must be cleared by AEC and DOD prior to publication. (51-1)

2. Assembly Systems [Note 6]

a. Gun type

(1) Mere fact that this method may be used to achieve criticality. (51-1)

(2) The description of the propellant material of gun-type weapons. (62-7)

(3) Fact that a specific weapon is gun-type. (67-1)

b. Implosion type

(1) Mere fact that this method may be used to achieve criticality. (51-1)

(2) Moments of inertia of HE implosion type weapons. (62-7)

(3) Fact that a specific weapon is implosion type except for one classified weapon. (67-1)

c. Mere fact that either method may be used to achieve criticality. (53-1)

d. Design or Functioning of Nuclear Weapons and Components thereof

(1) Implosion weapons

(a) Explosive system; raw materials and detonator cables (unless revealing classified information). (56-3)

(b) In-flight insertion; mere fact that U.S. has a system for nuclear arming of bombs while carrier is in flight (no other details). (56-3)

(2) The definition of a capsule. (67-1)

(3) The fact that the IFI (in-flight insertion of a nuclear material capsule or other nuclear part) safing method was applied to designated, retired weapons. (80-1)

e. Revealing the general fact of existence of nuclear weapons which contain only Pu-239. (67-1) (See also II.M.18.)

f. Use of normal cascade top product in specific weapons. (67-1)

g. Fact of use in specified or unspecified weapons of normal uranium or depleted uranium of any assay. (67-1) (See also II.G.26.)

h. Quantity of Be used outside the nuclear assembly systems. (67-1) (See also II.C.5.)

i. The total quantity of Be used in the nuclear weapons program. (67-1) (See also II.C.6.)

j. The fact of use of B-10 for hardening in unspecified nuclear weapons. (67-1) (See also II.L.3.)

k. The mere fact that delta phase Pu has been or is used in weapons. (67-1) (See also II.M.19.)

l. The fact that (various explosive materials) TNT, RDX, HMX, PETN, RDX COMPOSITION B, RDX COMPOSITION B3, 75/25 CYCLOTOL, BARATOL, TETRYL, PBX 9007, PBX 9010, PBX 9011, PBX 9404, PBX 9407, LX-04, and LX-07, are used in specific weapons. (67-1)

m. Fact of use of extrudable explosives in unspecified weapons. (67-1)

n. The fact of use in high explosive assembled (HEA) weapons of spherical shells of fissile materials, sealed pits; air and ring HE lenses; that multipoint detonation systems may be used in weapons, and a definition of pre-initiation - proof weapons (weapon, the yield of which is not sensitive to initiation of the nuclear reaction at a time earlier than the planned time). (72-11)

o. The fact of boosting, the fact that deuterium and tritium are used as boosting fuels in HEA weapons and that they are contained in components known as reservoirs or cartridges which are shipped between the Savannah River Plant and the AEC weapon facilities, the military and the United Kingdom. (72-11) (See also II.A.8. and II.B.8.)

(1) The fact that some high-explosive assembled (HEA) weapons (specified or unspecified) may be boosted or are boosted. (83-2)

(2) Physical state of boosting fuel in HEA weapons. (83-2)

(3) Fact that gaseous deuterium (D) and tritium (T) are used as boosting fuel. (83-2) (See also II.A.8.a. and II.B.8.a.)

(4) The fact that gas boosting is used in specified weapons. (83-3)

(5) Declassification of reservoir information: The safety factor, defined as the ratio of test pressure to maximum working pressure that a reservoir is calculated to experience during its use, for unspecified or specified reservoirs. (93-2)

(6) Boosting information:

(a) The term "hollow boosting." (93-2)

(b) Its definition: "A method wherein the boost gas is in a hollow pit at detonation time." (93-2)

p. The fact of existence of the weapons with tailored outputs, e.g., enhanced x-ray, neutron or gamma-ray output; that we are hardening our weapons to enhance weapon outputs and that high-Z materials are used in hardening nuclear weapons against high- energy x-rays. (72-11)

q. The mere fact that Be is used in the nuclear assembly system of designated weapons. (72-11) (See also II.C.7.)

r. The fact of existence of a deep-earth penetration fuzing option. (72-11)

s. The mere fact that hollow pits are used as nuclear components. (72-9)

t. The mere fact that weapons may be safed by the insertion of inert materials into the pit. (72-9)

u. The mere fact that some of our nuclear weapons are inherently safe. (72-9)

v. Limited Try - That feature of a coded switch which permits insertion of code possibilities only up to an established number; code tries in excess of an established number may result in a delay or lockout. (73-4)

w. The fact that the MK7 nuclear weapon employed an in-flight- insertion, "levitated pit" design of the type having an airspace between the tamper and core. (79-2)

x. Fact that multidimensional radiation - hydrodynamic codes are used for weapons design. (83-5)

y. Fact of use of slapper detonators in specified weapons. (83-5)

z. Fact of use of multiport valves in specified weapons. (83-5)

aa. Information concerning LLNL's Waxwing device or similar insertable nuclear component (INC) concepts.

(1) The fact that the (HE) used for imploding fissile components of the INC is stored as a paste in the missile body awaiting transfer to a final location. (85-1)

bb. The existence of, or the capability to design, implosion assembled weapons with diameters of 6 inches or more. (88-4)

cc. The concept of storing hydrogen isotopes in solid or liquid compounds in undesignated weapons. (88-4)

dd. Fact that tritium is associated with some unspecified pits. (92-4) (See also II.B.11.)

ee. Declassification of pit bonding information:

(1) Fact that bonding of plutonium or enriched uranium to materials other than themselves is a weapon production process. (93-2)

(2) Fact that such bonding occurs or may occur to specific unclassified tamper, alpha-barrier or fire resistant materials in unspecified pits or weapons. (93-2)

(3) Fact that plutonium and uranium may be bonded to each other in unspecified pits or weapons. (93-2)

(4) Fact that such bonding may be diffusion bonding accomplished in an autoclave or may be accomplished by sputtering. (93-2)

(5) Fact that pit bonding/sputtering is done to ensure a more robust weapon or pit. (93-2)

(6) The use of autoclaves in pit production. (93-2)

(7) The fact that plutonium is processed in autoclaves. (93-2)

(8) The fact that sputtering of fissile materials is done at or for any Department of Energy facility as a production process. (93-2)

(9) The fact of a weapons interest in producing a metallurgical bond between beryllium and plutonium. (93-2)

(10) The fact that beryllium and plutonium are bonded together in unspecified pits or weapons. (93-2)

(11) Routine data concerning concentrations of beryllium in plutonium higher than 100 ppm. (93-2)

ff. That plutonium-239 or weapon-grade plutonium is used:

(1) In unspecified implosion assembled weapons or pits of unspecified staged weapons. (93-2) (See also II.M.28.a.)

(2) As the sole fissile material in unspecified implosion assembled weapons, or in the pit of unspecified staged weapons. (93-2) (See also II.M.28.b.)

gg. Fissile shell information: The fact of use of thin spherical shells of fissile materials in weapons, without elaboration. (93-2)

hh. Special nuclear materials masses: That about 6 kg plutonium is enough hypothetically to make one nuclear explosive device. (93-2) (See also II.M.29)

ii. Hypothetically, a mass of 4 kilograms of plutonium or uranium-233 is sufficient for one nuclear explosive device. (94-1)

NOTE: The average masses of special nuclear materials in the U.S. nuclear weapons or special nuclear materials masses in any specific weapon type remain classified.

3. Initiators:

a. The fact that a modulated external initiator is possible or is used and the fact that initiators of the accelerator type are feasible or are used. (59-7)

b. Fact that an initiator may be or may not be needed in gun- assembled weapons. (59-7)

(1) Fact that initiators may or may not be needed in gun-type weapons. (62-7)

c. The existence and use of modulated initiators of the alpha-n type and that they can use Ac-227, Po-210, Ra-226 and Pu-238. (62-7)

(1) Fact that Po-210 is used in weapon initiators. (67-1) (See also II.D.4.)

d. The fact that accelerator-type initiators are used in gun-assembled weapons. (71-10)

e. The fact that mechanically operated power supplies for accelerator- type initiators are used in gun-assembled weapons. (71-10)

f. The fact that accelerator-type initiators are used in specific weapons. (71-10)

g. The fact that designated weapons are internally initiated. (72-11)

h. Number of neutron generators used in specified weapons. (83-5)

i. External weapon initiator information: The weights, volumes, and physical dimensions of external weapon initiators (neutron generators). (93-2)

4. External characteristics:

a. Visible size and shape only of specifically listed obsolete weapons of historic interest including replicas and miniatures including nickname, code and model designations:
Trinity
Nagasaki
Hiroshima
Bikini-Able (w/o external antenna)
Little Boy
Mk-3
(53-1)

b. Nuclear test device shipping and handling containers not revealing nuclear or military characteristics. (53-1)

c. Visible size and shape of externally carried bombs [Note 7] when object is not specifically identified as an atomic weapon and no other information concerning the nature or purpose of the object is revealed to observers. (53-1)

(1) The size, weight and shape of externally carried atomic bombs [Note 7]. (54-2)

d. The size, weight and shape of the 280 MM Atomic Artillery Shell, Mod 0-22 (Army designation: M-354, AEC designation Mark 9). The declassification of the size, weight and shape of artillery-fired atomic shells other than the MK 9 will be considered by AEC-DOD on an individual basis. (54-2)

e. The actual shape, dimensions and weight of the 8-inch artillery shell. (Army designation T317, AEC designation TX 33) (56-2)

f. Actual size, shape, weight, center of gravity, or moments of inertia of fission or boosted fission weapons when identifiable as nuclear weapons provided other classified information is not included. Fat Man, Little Boy, MK 3, MK 4, MK 5 and MK 6 only. (57-4)

g. The actual shape, dimensions and weight of any artillery (or naval rifle) shell whose diameter is equal to or greater than 8 inches. This information will be classified only if the existence of the delivery system is considered classified by the DoD. (57-4)

h. Only such information on the weight of the assembled Davy Crockett weapon as revealed by observation of the physical handling. Note should be taken of the great importance of safeguarding the yield of the Davy Crockett. (60-1)

i. The size, weight, and shape of weapons or missile warheads when in the hands of troops for training, or when final flight test configuration is reached. (62-7)

5. Type of fissionable material used (no reference to quantities; detailed assembly, etc). (53-1)

a. Identification of the type of fissionable materials used in Trinity, Hiroshima, Nagasaki, Bikini-Able, and Bikini-Baker models. (53-1)

b. Use in weapons of normal, depleted or fully enriched uranium and the identification of the fissionable materials used in a specific fission weapon. (59-7) (See also II.G.25.)

c. The fact that reactor grade plutonium can be used to make nuclear weapons. (67-9) (See also II.M.21.)

d. The mere fact that high irradiation level reactor-grade plutonium can be used to make nuclear weapons. (67-10) (See also II.M.22.)

6. Fuzing and Firing Systems [Note 8]

a. The fact that baro, radar, timer, impact, etc., elements may be included in the fuzing systems of atomic weapons. Does not include other details of fuzing system. (53-1)

b. The fact that specific models of nuclear depth bombs of nuclear depth charges use hydrostatic switches to effect a nuclear detonation. (59-6)

c. New developments in non-radiating fuzing for nuclear weapons when evaluation by AEC and DoD indicates no classified information involved. (67-1)

d. The fact of use of ferroelectric or ferromagnetic devices as firing sets in specific weapons. (71-10)

e. Fact of use of compressed-magnetic-field firing sets in specified weapons. (83-5)

7. Nomenclature and Description. (56-3)

a. Mere mention of a nuclear weapon by mark, model, service nomenclature number, or code word, whether or not it reveals the device as a nuclear weapon. (56-3)

b. Actual size, weight, center of gravity or moments of inertia of fission weapons when identifiable as nuclear weapons provided information classified by other topics is not included. (56-3)

(1) Obsolete weapons (Fat Man, Little Boy, MK 3 and MK 4 only). Provided external antennae removed. (56-3)

(2) Externally carried weapons. (56-3)

(3) Warheads when completely covered by ballistic case. (56-3)

(4) Shipping and handling containers not revealing nuclear or military information. (56-3)

8. Technology

a. Weapon reliability; Inspection of weapons: Mere fact that such inspections are made. (56-3)

b. Mere existence of the phenomenon of predetonation. (56-3)

c. The term "dial-a-yield" (DAY) and fact of its applicability to undesignated weapons. (89-3)

d. Fact of use of varistors as high voltage limiters. (91-1)

e. Fact that non-spherical parts are used in some weapons, part unidentified, weapon undesignated. (91-1)

f. Fact that fissile and/or fissionable materials are present in some secondaries, material unidentified, location unspecified, use unspecified, and weapons undesignated. (91-1)

g. Fact that multipoint detonation systems are used in undesignated weapons. (91-1)

h. Fact of use of boron carbide in undesignated weapons. (91-1)

i. Fact that the thermal stability of pentaerythritol tetranitrate (PETN) in an undesignated weapon is improved by baking or by adding tripentaery thritol octanitrate, polysaccharide, or other specific additions. (92-2)

j. Primary/secondary information: The identity of a designated device nickname/acronym as a primary or secondary. (93-2) (See also V.D.19)

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