3 October 2021

NUCLEAR WEAPONS TECHNOLOGY 101

Bruce Goodwin

Introduction 

Policymaking for nuclear security requires a strong grasp of the associated technical matters. That grasp came naturally in the early decades of the nuclear era, when scientists and engineers were deeply engaged in crafting policy. In more recent decades, the technical community has played a narrower role, one generally limited to implementing policies made by others. This narrower role has been accentuated by generational change in the technical community, as the scientists and engineers who conceived, built, and executed the programs that created the existing U.S. nuclear deterrent faded into history along with the long-term competition for technical improvements with the Soviet Union. There is thus today a clear need to impart to the new generation of nuclear policy experts the necessary technical context. That is the purpose of this paper. Specifically, to: introduce a new generation of nuclear policy experts to the technical perspectives of a nuclear weapon designer, explain the science and engineering of nuclear weapons for the policy generalist, review the evolution of the U.S. approach to nuclear weapons design, explain the main attributes of the existing U.S. nuclear stockpile, explain the functions of the nuclear weapons complex, and show how all of this is integrated to sustain future deterrence. I wish to acknowledge Thomas Ramos, Richard Ward, and Jacek Durkalec for their invaluable contributions to this paper. Without them, it could not have been written.

The Revolution in Physics That Led to the Bomb

 First, a little history. I will use some technical terms in this section that may not be familiar. I beg your patience as I lay out the nuclear revolution. Following this, I will define these technical terms in excruciating detail before I describe the physics of nuclear weapons. You can also consult the glossary at the end of the paper. Nuclear weapons came into being from the scientific advancements that occurred in the five decades from 1895 to 1945. It begins with Roentgen’s 1895 discovery of radiation in the form of X-rays. Then in 1905, Albert Einstein developed his Special Theory of Relativity positing that matter and energy could change from one form to the other. The next necessary technical advance was Chadwick’s 1932 discovery of the neutron. The final technical step was the discovery in 1938-1939 of fission by Otto Hahn and Lisa Meitner. This final development led Niels Bohr to quietly voice concerns to the UK government over the possibility of atomic weapons development by Nazi Germany. Thus, the MAUD committee was created to study the feasibility of an atomic bomb. This group wrote the UK MAUD report and transmitted that report to the U.S. government in 1941. It was given to the United States as it was realized that only America had the industrial capacity to produce the nuclear materials needed to determine if an atomic (i.e. a fission) bomb was feasible. By the way, some have hypothesized that the codename MAUD stood for the Military Application of Uranium Detonation. This is not true. In fact, Maud was the name of Niels Bohr’s housekeeper.1 Things then began to move very quickly. In February 1941, Glenn Seaborg discovered plutonium (Pu), the first manmade fissionable element, thus doubling the possible paths to a bomb. He did this by bombarding uranium-238 with neutrons. After Pearl Harbor brought the U.S. into World War II in December 1941, the Manhattan Engineering District (a code name), under the direction of General Leslie Groves, was formed in May of 1942 to develop the atomic bomb. This was followed by the establishment of the Los Alamos Scientific Laboratory on November 25, 1942, under the direction of Dr. J. Robert Oppenheimer of the University of California, Berkeley. The first manmade fission chain reaction was achieved on December 2, 1942, by Enrico Fermi’s team in the first nuclear reactor (a graphite pile reactor) under the grandstands of The University of Chicago stadium.

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