from the FAS Project on Government Secrecy
Volume 2009, Issue No. 75
September 21, 2009

Secrecy News Blog:


A book published this year in Brazil on "The Physics of Nuclear Explosives" prompted concerns at the International Atomic Energy Agency (IAEA) that it revealed classified nuclear weapons design information and that it might signify a renewed interest by Brazil in developing such weapons. The U.S. Government also requested further details on the matter, the Brazilian press reported.

According to the Jornal do Brasil, which first disclosed the controversy on September 6, the IAEA "wanted the book to be recalled" and demanded more information on the author's work. The government of Brazil refused to censor the book and rejected what it described as IAEA interference.

"The Physics of Nuclear Explosives" ("A Física dos Explosivos Nucleares") by Dalton E.G. Barroso provides a rather comprehensive account of the physical principles involved in nuclear detonations, including both fission and fusion weapons. There are chapters on reactor physics, radiation hydrodynamics, dynamic compression of solids, inertial confinement fusion, and more. Most of this information is already freely available to those who care to search for it. But the author has broken new ground in presenting the results of his numerical simulations of nuclear detonations and characterizations of particular weapons, such as the W-87 warhead.

"One presumes that many of the specific results presented here have never been published in the open scientific literature," he wrote in the Preface to the book. "However, such results are based on well-known physical and mathematical models."

Far from implying that Brazil may have a clandestine nuclear weapons program, Defense Minister Nelson Jobim said that the absence of official secrecy surrounding the book demonstrated that the opposite was the case. "The mere possibility of publishing this work in Brazil, and the material's free circulation, serve as eloquent proof of the non-existence of an unauthorized nuclear program in the country."

Dr. Barroso made the same point to Secrecy News. "My research is academic and has only scientific interest, for if it is not so, how could my book be published?" "A Física dos Explosivos Nucleares" by Dalton E.G. Barroso, now in its second edition, was published by Livraria da Física (439 pages, 2009, in Portuguese).


Brazil's nuclear energy research programs and facilities are described in two recent publications of the DNI Open Source Center. These documents have not been approved for public release, but copies were obtained by Secrecy News.

"Brazil -- Survey of Nuclear Agencies, Facilities," February 9, 2009:

"Brazil -- Websites, Online Publications Seek to Inform Public on Nuclear Activities," August 5, 2009:


Secrecy News is written by Steven Aftergood and published by the Federation of American Scientists.

See also "Reducing Government Secrecy: Finding What Works" by Steven Aftergood, Yale Law and Policy Review, vol. 27, no. 2, Spring 2009:

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