The Teller–Ulam design was for many years considered one of the top nuclear secrets, and even today it is not discussed in any detail by official publications with origins "behind the fence" of classification. United States Department of Energy (DOE) policy has been, HP Compaq HSTNN-OB52 Battery
and continues to be, that they do not acknowledge when "leaks" occur, because doing so would acknowledge the accuracy of the supposed leaked information.
Aside from images of the warhead casing, most information in the public domain about this design is relegated to a few terse statements by the DOE and the work of a few individual investigators. HP Compaq HSTNN-OB62 Battery
In 1972 the United States government declassified a statement that "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'", and in 1979 added, HP Compaq HSTNN-UB05 Battery
"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." To this latter sentence they specified that "Any elaboration of this statement will be classified." HP Compaq HSTNN-UB11 Battery
The only statement which may pertain to the spark plug was declassified in 1991: "Fact that fissile and/or fissionable materials are present in some secondaries, material unidentified, location unspecified, use unspecified, and weapons undesignated." HP Compaq HSTNN-UB18 Battery
In 1998 the DOE declassified the statement that "The fact that materials may be present in channels and the term 'channel filler,' with no elaboration", which may refer to the polystyrene foam (or an analogous substance).
Whether these statements vindicate some or all of the models presented above is up for interpretation, HP Compaq HSTNN-UB68 Battery
and official U.S. government releases about the technical details of nuclear weapons have been purposely equivocating in the past (see, e.g.,Smyth Report). Other information, such as the types of fuel used in some of the early weapons, has been declassified, though of course precise technical information has not been. HP Compaq HSTNN-UB69 Battery
Most of the current ideas on the workings of the Teller–Ulam design came into public awareness after the Department of Energy (DOE) attempted to censor a magazine article by U.S. antiweapons activist Howard Morland in 1979 on the "secret of the hydrogen bomb". HP Compaq HSTNN-W42C Battery
In 1978, Morland had decided that discovering and exposing this "last remaining secret" would focus attention onto the arms race and allow citizens to feel empowered to question official statements on the importance of nuclear weapons and nuclear secrecy. HP Compaq HSTNN-W42C-A Battery
Most of Morland's ideas about how the weapon worked were compiled from highly accessible sources—the drawings which most inspired his approach came from none other than the Encyclopedia Americana. Morland also interviewed (often informally) many former Los Alamos scientists (including Teller and Ulam, HP Compaq HSTNN-W42C-B Battery
though neither gave him any useful information), and used a variety of interpersonal strategies to encourage informative responses from them (i.e., asking questions such as "Do they still use spark plugs?" even if he was not aware what the latter term specifically referred to). HP Compaq HSTNN-XB0E Battery
Morland eventually concluded that the "secret" was that the primary and secondary were kept separate and that radiation pressure from the primary compressed thesecondary before igniting it. When an early draft of the article, to be published in The Progressive magazine, HP Compaq HSTNN-XB11 Battery
was sent to the DOE after falling into the hands of a professor who was opposed to Morland's goal, the DOE requested that the article not be published, and pressed for a temporary injunction. The DOE argued that Morland's information was (1) likely derived from classified sources, HP Compaq HSTNN-XB18 Battery
(2) if not derived from classified sources, itself counted as "secret" information under the "born secret" clause of the 1954 Atomic Energy Act, and (3) was dangerous and would encourage nuclear proliferation.
Morland and his lawyers disagreed on all points, HP Compaq HSTNN-XB21 Battery
but the injunction was granted, as the judge in the case felt that it was safer to grant the injunction and allow Morland, et al., to appeal, which they did in United States v. The Progressive (1979).
Through a variety of more complicated circumstances, HP Compaq HSTNN-XB24 Battery
the DOE case began to wane as it became clear that some of the data they were attempting to claim as "secret" had been published in a students' encyclopedia a few years earlier. After another H-bomb speculator, Chuck Hansen, had his own ideas about the "secret" (quite different from Morland's) HP Compaq HSTNN-XB28 Battery
published in a Wisconsin newspaper, the DOE claimed that The Progressive case was moot, dropped its suit, and allowed the magazine to publish its article, which it did in November 1979. Morland had by then, however, changed his opinion of how the bomb worked, HP Compaq HSTNN-XB51 Battery
suggesting that a foam medium (the polystyrene) rather than radiation pressure was used to compress the secondary, and that in the secondary there was a spark plug of fissile material as well. He published these changes, based in part on the proceedings of the appeals trial, as a short erratum in The Progressive a month later. HP Compaq HSTNN-XB52 Battery
In 1981, Morland published a book about his experience, describing in detail the train of thought which led him to his conclusions about the "secret".
Morland's work is interpreted as being at least partially correct because the DOE had sought to censor it, HP Compaq HSTNN-XB59 Battery
one of the few times they violated their usual approach of not acknowledging "secret" material which had been released; however, to what degree it lacks information, or has incorrect information, is not known with any confidence. HP Compaq HSTNN-XB61 Battery
The difficulty that a number of nations had in developing the Teller–Ulam design (even when they apparently understood the design, such as with the United Kingdom), makes it somewhat unlikely that this simple information alone is what provides the ability to manufacture thermonuclear weapons. HP Compaq HSTNN-XB62 Battery
Nevertheless, the ideas put forward by Morland in 1979 have been the basis for all the current speculation on the Teller–Ulam design.
There have been a few variations of the Teller–Ulam design suggested by sources claiming to have information from inside of the fence of classification. HP Compaq HSTNN-XB68 Battery