<u>Nuclear Weapons: What You Need to Know</u>

By Jeremy Bernstein
Reviewed by Cameron Reed

(Cambridge: Cambridge University Press, 2008) ISBN 978-0-521-88408-2, xi + 299 pp, $27.

Readers familiar with Jeremy Bernstein's writing know that, upon picking up one of his books or articles, they are always in for a good read: accurate, well-described physics, interesting historical sidelights, and engaging personality profiles and personal anecdotes. In his careers as both a physicist at the Stevens Institute of Technology and as a science journalist for the New Yorker Bernstein has worked with, interviewed, and/or personally known many of the key figures of twentieth-century physics. He draws on that experience to good effect in his latest work.

This book is a history of nuclear weapons written to address the "appalling lack of understanding" of these devices on the part of the general public and the misinformation offered by media commentators as they attempt to explain issues of weapons programs and proliferation. The author points out that it has been nearly 30 years since a human being has actually witnessed an aboveground nuclear test and that the ranks of those who can personally testify to the power of these devices is steadily dwindling: humanity needs to be reminded what is at stake when a single Nagasaki-type bomb is equivalent to some 8000 Oklahoma City truck bombs.

This book comprises an introduction, twelve chapters, and a handy table of units and sizes. The first three chapters offer a brief tour of the history of the elucidation of atomic structure from the work of Thomson up to the discovery and interpretation of fission. Chapter 4 takes up the work of Bohr and Wheeler on the theory of fission, along with Leo Szilard and his role in Einstein's letter to President Roosevelt. Chapter 5 describes the process of fission, the work of Fermi and Szilard in looking for prompt neutrons which could sustain a chain reaction, the Frisch-Peierls memorandum, the concept of critical mass, and the British MAUD report. Chapter 6 offrers a brief description of the periodic table before moving on to Lawrence's development of cyclotrons and the work of McMillan, Abelson, and Seaborg in synthesizing and isolating plutonium. Particularly interesting in this regard is the largely unappreciated early work of William Zachariasen in trying to establish the density of that unusual element, experiments which were confounded by the simultaneous presence of a number of allotropic forms. This chapter concludes with a description of Fermi's Chicago pile and how that led to the Hanford piles.

Chapter 7 offers a detailed description of how Robert Serber's Los Alamos Primer lays out many of the scientific and technical challenges of building atomic bombs and associated issues such as initiation and spontaneous fission. Chapter 8 is devoted to the plutonium bomb, the spontaneous fission crisis of 1944, work on the metallurgy of plutonium, and the difficulty of developing an implosion assembly.

Chapter 9 is the most personal of this work, a description of how the author came to be an intern at Los Alamos in 1957 and had the opportunity to witness two aboveground tests and to hold a bomb core in his hands. He relates how this experience made him feel that he had crossed a divide into a secret world that had given him some kind of power, a feeling that he did not appreciate as absurd until some time later. This sets the stage for a detailed description of what actually happens in a nuclear explosion from the moment of "second criticality" (when more neutrons are escaping than causing fissions) to the formation of the now-iconic mushroom cloud and the consequent effects. Chapter 10 reviews the development of fusion weapons, emphasizing the contributions of Fuchs, von Neumann, Ulam and Teller toward the development of practical hydrogen bombs. Chapter 11 examines the German nuclear program, the response of German scientists to the news of Hiroshima, and espionage at Los Alamos with emphasis on what Klaus Fuchs transmitted to the Russians.

Chapter 12 examines some of the history of nuclear proliferation. Bernstein outlines how German scientists captured by Russia at the end of World War II aided that country in centrifuge development. One of these men, Gernot Zippe, returned to the West in 1956 and carried plans in his head, information that came to A. Q. Khan, who was then working in the Netherlands. Khan offered his services to his adopted country of Pakistan and soon had his own laboratory. The story of Khan's deals with China, North Korea, Iraq, Iran and Libya to trade centrifuge plans and parts for bomb designs, missiles and substantial amounts of money is chilling. This chapter concludes with a summary of current nuclear weapon states and numbers of warheads along with brief discussions of the complications of reactor-grade plutonium in proliferation issues and the North Korean test of October 2006. Bernstein reminds us that the most important aspect of inhibiting proliferation is to secure fuel fabrication.

I found a few errors in this book. Figure 16 (p. 130) shows the projectile piece in a gun-type bomb being shot toward the tail from the nose. A description of the implosion process on p. 150 is reversed from the accompanying diagram. Equations concerning fusion reactions on pages 205 and 209 have suffered some minor typesetting errors. However, these should not cause great difficulties for readers, especially those familiar with the physical ideas to begin with.
In contrast to Richard Rhodes' monumental The Making of the Atomic Bomb with its many diversions, Bernstein has produced a compact description of the underlying physics and development of nuclear weapons that is scientifically meaty while remaining accessible and engaging to intelligent lay readers willing to work through it; it is to be highly recommended. Finally, full disclosure: I am grateful to Dr. Bernstein for acknowledging me in this book for having pointed out a minor numerical error in his recently-published Plutonium.

Cameron Reed,
Department of Physics,
Alma College, Alma, MI 48801