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History of the Teller–Ulam design

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Vitruvius
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« Reply #15 on: September 06, 2007, 12:04:04 am »



Photographs of warhead casings, such as this one of the W80 nuclear warhead, allow for some speculation as to the relative size and shapes of the primaries and secondaries in U.S.
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Vitruvius
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« Reply #16 on: September 06, 2007, 12:04:40 am »

Public knowledge

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, and continues to be, that they do not acknowledge when "leaks" occur, because doing such would acknowledge the accuracy of the supposed leaked information. Aside from images of the warhead casing (but never of the "physics package" itself), most information in the public domain about this design is regulated to a few terse statements by the DOE and the work of a few individual investigators.

Below is a short discussion of the events which lead to the formation of these "public" models of the Teller-Ulam design, with some discussions as to their differences and disagreements with those principles outlined above.

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Vitruvius
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« Reply #17 on: September 06, 2007, 12:05:37 am »

DOE statements

In 1972, the DOE 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: "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." (emphasis in original) The only statement which may pertain to the sparkplug 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." 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). (DOE 2001, sect. V.C.)

Whether these statements vindicate some or all of the models presented above is up for interpretation, and official U.S. government releases about the technical details of nuclear weapons have been purposely equivocating in the past (see, i.e., 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.

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Vitruvius
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« Reply #18 on: September 06, 2007, 12:06:47 am »



Most of what is known today in the public domain about the Teller-Ulam design comes from a 1979 article in a left-wing magazine.
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Vitruvius
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« Reply #19 on: September 06, 2007, 12:07:30 am »

The Progressive case

Most of the current ideas of what the Teller-Ulam design came into public awareness after the DOE attempted to censor a magazine article by U.S. antiweapons activist Howard Morland in 1979 on the "secret of the hydrogen bomb". 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. 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, though neither gave him any useful information), and used a variety of interpersonal strategies to encourage informational responses from them (i.e., asking questions such as "Do they still use sparkplugs?" even if he wasn't aware what the latter term specifically referred to). (Morland 1981)

Morland eventually concluded that the "secret" was that the primary and secondary were kept separate and that radiation pressure from the primary compressed the secondary before igniting it. When an early draft of the article, to be published in The Progressive magazine, 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. After a short court hearing in which the DOE argued that Morland's information was 1. likely derived from classified sources, 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, 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, et al. (1979).

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« Reply #20 on: September 06, 2007, 12:08:35 am »



The attempted censorship of the article by Howard Morland (above) attracted large amounts of press attention to his version of the "secret" and seemed to validate its accuracy.
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Vitruvius
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« Reply #21 on: September 06, 2007, 12:09:36 am »

Through a variety of more complicated circumstances, 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) published in a Wisconsin newspaper, the DOE claimed The Progressive case was moot, dropped their suit and allowed the magazine to publish, which it did in November 1979. Morland had by then, however, changed his opinion of how the bomb worked, suggesting that a foam medium (the polystyrene) rather than radiation pressure was used to compress the secondary, and that in the secondary was a sparkplug of fissile material as well. He published these changes, based in part on the proceedings of the appeals trial, as a short errata in The Progressive a month later. 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 1981; DeVolpi 1981)

Because the DOE sought to censor Morland's work—one of the few times they violated their usual approach of not acknowledging "secret" material which had been released—it is interpreted as being at least partially correct, though to what degree it lacks information or has incorrect information is not known with any great confidence. The difficulty which 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. Nevertheless, the ideas put forward by Morland in 1979 have been the basis for all current speculation on the Teller-Ulam design.

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