The Manhattan Project Resources

U.S. Department of Energy logos U.S. Department of Energy Office of Environment, Health, Safety and Security Office of History and Heritage Resources

Drawing Back the Curtain of Secrecy, section V.D through V.H


1. Research and development (includes reactions involving deuterium and tritium)

a. Physics of the light elements. (51-1)

b. General statements concerning the relationship of commonly known nuclear reactions of the light elements to developmental work on thermonuclear weapons. (51-1)

2. Thermonuclear test devices shipping and handling container not revealing nuclear or military characteristics. When object is not specifically identified as an atomic weapon and no other information concerning the nature or purpose of the object is revealed. (53-4)

3. Lithium and its compounds

a. Lithium enriched in the isotope Li6; Material up to and including 1 kilogram contained Li6 total. (54-2)

b. Lithium enriched in the isotope Li7; Material up to 15 kilograms total contained Li7. (54-2)

c. Other normal lithium compounds. (54-2)

d. The fact that lithium, deuterium (Li6D, LiD) are used in unspecified thermonuclear weapons. (62-7) (See also II.Q.7.)

e. The mere fact that normal Lithium Deuteride (LinD) is used in unspecified TN weapons. (67-1) (See also II.Q.9.)

f. The assay of top product of Li6 production plant or the fact that this top assay is used in weapons. (67-1) (See also II.Q.10.)

g. The fact that Li6H is used in unspecified weapons for hardening. (67-1) (See also II.Q.11.)

h. The fact the Li7H or LinH may be used as mockup materials in the weapons program. (67-1) (See also II.Q.12.)

i. The fact that compounds of Li6 containing tritium are used in the design of weapons as TN fuel. (72-11) (See also II.B.9. and II.Q.13.)

4. The date or estimate of the date when a thermonuclear weapon may be an actuality. (54-2)

5. Visible size and shape only of externally carried thermonuclear weapons when not identifiable as such. (57-1)

6. The size, weight and shape of some thermonuclear weapons (Any information which reveals the existence of thermonuclear weapons with diameter less than 24" or weight less than 2000 lb is classified). (59-7)

a. Size, weight and shape of some thermonuclear weapons (Any information which reveals the existence of thermonuclear weapon with diameter less than 18 inches or weight less than 690 pounds is classified). (60-1)

b. The existence of, or the capability to design, a thermonuclear (TN) weapon assembly system with a diameter of 8 inches or more. (88-4)

7. The fact that certain of our operational missiles have thermonuclear warheads. (62-7)

8. The fact that tests were conducted of designs which could lead to an entirely new class of U.S. weapons which could have relatively low weights and extremely high yields, with the fission contributions decreased to only a few percent of the total yield. (63-1) (See also V.B.5.b.)

9. The fact that the yield-to-weight ratios of the new class of weapons would be more than twice that which can now be achieved in the design of very high yield weapons using previously developed concepts. (63-1)

10. The United States, without further testing, can develop a warhead of 50-60 Mt for B-52 delivery." (63-3)

11. "... some improvement in high yield weapons design could be achieved and that new warheads -- for example a 35 Mt warhead for our Titan II -- based on these improvements could be stockpiled with confidence." (63-3)

12. The salvage value of the Mark 28 Nuclear Weapon recovered off the coast at Palomares, Spain, was $164,000. (67-4)

13. The fact that approximately 6 kgs of plutonium were involved in theGreenland accident. (68-4)

a. Best estimate of the amount of plutonium removed from the site. (68-4)

14. Information revealing the mere existence of TN devices with total yield equal to or greater than 5 KT. (68-8)

15. The fact that the total number of Spartan and Sprint interceptors planned for the 4-site option at Minuteman sites is 120 Spartans and 264 Sprints. (71-3)

16. The nuclear device to be tested in the Cannikin event is related to the optimum development of a warhead for the Spartan missile of our Safeguard Ballistic Missile Defense Program. The measurements of device performance which will be obtained from the test are essential to our optimum defense deployment of safeguards for protection of our Minuteman missile sites. (71-9) (See also V.B.3.rr.)

17. The fact that in thermonuclear (TN) weapons, a fission "primary" is used to trigger a TN reaction in thermonuclear fuel referred to as a "secondary". (72-11)

18. The fact that, in thermonuclear weapons, radiation from a fission explosive can be contained and used to transfer energy to compress and ignite a physically separate component containing thermonuclear fuel. (79-2)

Note: Any elaboration of this statement will be classified.

19. Primary/secondary information: The identity of a designated device nickname/acronym as a primary or secondary. (93-2) (See also V.C.8.j.)

20. Secondary information: The fact that fissile and/or fissionable materials are present in some secondaries, materials unidentified except for uranium (depleted, natural, and enriched including highly enriched uranium), location unspecified, use unspecified, and weapon undesignated. (93-2)

21. Radiation case material information for unspecified weapons only:

a. The fact of use of specific elements with atomic number (Z) greater than 71 as radiation case materials. (93-2)

b. The fact of use of specific unclassified alloys as radiation case materials. (93-2)


1. The fact that DOE weapon laboratories are engaged in a research program to explore the feasibility of a nuclear explosive driven directed energy weapon. (82-2)

2. The fact that research is being conducted on the specific concept of a nuclear pumped X-ray laser. (82-2)

3. Information concerning Nuclear Directed Energy Weapons (NDEW).

a. The fact that the DOE is interested in or conducting research on NDEW concepts of certain specified generic types of output; i.e., visible light, microwaves, charged particles, kinetic energy. (85-4)

b. The fact that underground tests at the Nevada Test Site have been and are a part of the NDEW research program. (85-4) (See also V.B.3.hhh.)

c. The fact that a specified NDEW could engage multiple targets by using multiple beams from a single platform and hence is a high leverage system. (85-4)

d. The fact that an NDEW could have lethal ranges of thousands of kilometers. (85-4)

e. The fact that a kill mechanism for an x-ray laser is ablative shock. (85-4)

4. Information concerning Directed Nuclear Energy Systems.

a. Generalized description of DNES principles, as well as general qualitative or quantitative information on the physics and technology of low-power DNES research, that does not substantially: (86-1)

(1) Assist others in development of DNES weapons; or

(2) Contribute to feasibility assessment of DNES weapon development; or

(3) Reveal programmatic directions.

b. General qualitative descriptions of DNES program goals or objectives that do not reveal classified milestones or achievements or specific design characteristics. Classified milestones and their achievements will be reviewed for release on a case-by-case basis. (86-1)

c. General studies of DNES special nuclear materials and their physical properties. Specific special nuclear materials which are developed for (and the specific conditions of their association with) classified DNES projects and test device designs will remain classified. (86-1)

d. General studies of other DNES materials and their physical properties. No material identities or associations will be declassified where such information may be used to infer classified DNES characteristics. (86-1)

e. General DNES computational techniques or analytical procedures. Computational techniques and procedures which utilize or reveal specific design or operational characteristics will remain classified. (86-1)


1. Existing storage site.

a. Official names(s), nickname(s), and/or location, when association with the Armed Forces Special Weapons Project (AFSWP) or AEC is not revealed. (53-1)

b. AEC storage sites (as pertains to all weapons in custody of AEC at a National Storage Site (NSS) and an Operational Storage Site (OSS)). (56-3)

c. Location

(1) When information does not explicitly reveal installation is a storage site for nuclear weapons. (56-3)

(2) DoD storage sites (as pertains to weapons in DoD custody only). With delivery organizations and operating forces in the U.S. or overseas. (56-3)

(a) Fact that particular aircraft squadron, naval vessel, or special weapons organization has capability of storing or handling nuclear weapons. (56-3)

d. The approximate location of some of the national stockpile sites and operational stockpile sites provided no indication is given as to the total number of storage sites. (59-7)

2. Future storage sites

a. Official name(s), nickname(s), and/or location, when association with AFSWP or AEC is not revealed. Future storage sites become existing storage sites at the time of administrative manning. (53-1)

3. Surveillance program. Mere existence of maintenance or surveillance program. (53-1)

4. "In certain areas Soviet nuclear technology equals and in some areas even exceeds that of the U.S., although our overall capability and means of delivery are believed to be superior to the Soviets." (62-1)

5. "The U.S. has a nuclear weapon in stockpile with a yield of approximately 25 megatons." (62-4)

6. "The world was shocked by the 60 megaton test on October 30th. The U.S. analysis has shown that this device used a lead jacket around the fusion materials, and gave only a few megatons fission. Thus the Russians reduced the fallout, especially that which might have fallen on their own country. If lead were replaced by uranium, the Russian device would give 100 megatons or slightly more." (62-4)

7. The identification of U.S. TX, XW, or Mark numbers with U.S. missile names. (62-7)

8. "In order to achieve it, we maintain a total number of nuclear warheads, tactical as well as strategic, in the tens of thousands." (63-3)

9. The fact that we have deployed thousands of tactical nuclear weapons in Europe. (63-4)

a. The fact that the total kiloton yield of these weapons is well in excess of ten thousand times the total yield of the nuclear weapons used at the end of World War II. (63-4)

10. "In presenting this proposal, it could be stated that 'several thousand' nuclear weapons could be involved." This statement is contained in a U.S. Position paper on the Destruction of Nuclear Weapons to Obtain Fissionable Materials for Transfer Under a Cutoff and Transfer Agreement. (65-3)

11. "The number of nuclear warheads in strategic alert forces has increased from 850 on June 30, 1961 to 2700 estimated as of June 30, 1965." (65-5)

12. "The fact that U.S. strategic forces have an inventory of nuclear warheads in excess of 5,000, that the number of nuclear warheads furnished to the Alliance and stored in inventory in Western Europe has exceeded 5,000 nuclear warheads, and that this number will increase by more than 20% during the next six months." (65-7)

13. The minimum spacing for specific nuclear weapons or nuclear components in storage or transit. (67-1)

14. Statements that qualitatively reveal that a nuclear weapon is satisfactory. (67-1)

15. Statements that quantitatively reveal specific component quality or reliability requirements. (67-1)

16. The fact that U.S. nuclear artillery shells are located in Germany. (73-6)

17. The estimated costs for the proposed improved nuclear artillery shells as $452,000 each for the MK-74 (155mm) and $400,000 each for the MK-75 (8 inch). (73-6)

18. The fact that any particular reactor product is being or has been stockpiled for military use. (73-8)

19. Information concerning the weapons stockpile: (81-1)
                                            Fiscal Year
                                   1945    1946    1947    1948
Number of non-nuclear components
1. Gun-type                          0       0      (0)     (2)
2. Implosion                         2       9     (29)    (53)
Number of nuclear components
3. Gun-type                          0       0       0       0
4. Implosion-type                    2       9      13      50

Numbers in parentheses declassified in 1976.

20. Descriptions of historical and future trends in the total number of nuclear weapons in, or megatonnage of, the total stockpile which are:

a. Qualitative. (82-1)

b. Expressed as a percentage change over any time period or on an unscaled graph with a scaled time axis for the past, present, or future up to and including the approved period of the current Nuclear Weapons Stockpile Memorandum (usually five fiscal years beyond the current fiscal year). (82-1)

Note: Remains classified if dramatic trend changes result from significant unplanned events such as major technical or production problems, sabotage, natural or man-made disasters, etc.

21. Descriptions of trends for any time period in nuclear weapon production or retirement rates which are qualitative, including relative comparisons of the production rate versus the retirement rate. (82-1)

22. The fact that the total nuclear weapons stockpile contains a few tens of thousands of weapons (no numbers specified). (82-1)

23. The unelaborated fact of the presence of U.S. nuclear weapons in the U.K. (84-1)


1. The mere fact that the U.S. is interested in pursuing a program to determine the characteristics of an "enhanced radiation" weapon (neutron bomb). (63-5)

2. The fact that we are interested in and are continuing studies on a weapon for minimizing the emerging flux of neutrons and internal induced activity. (67-1)

3. The fact that the W-79 is an enhanced radiation weapon. (78-1)


1. The fact of weapon laboratory interest in MRR devices. (76-3)

2. The fact of successful development of MRR devices. (76-3)

Table of Contents
Click here to read the next section.
Click here to read the previous section.