The development of nuclear fission chain reactors for the conversion of mass to energy and the transmutation of elements has brought into industrial prominence chemical substances and chemical engineering processes that a few years ago were no more than scientific curiosities. Uranium, formerly used mainly for coloring glass and ceramics, has become one of the world’s most important sources of energy. Thorium, once used mainly in the Welsbach gas mantle, promises to become a nuclear fuel second in importance only to uranium. Zirconium and its chemical twin hafnium, formerly always produced together, have been separated and have emerged as structural materials of unique value in reactors. New chemical engineering processes have been devised to separate these elements, and even more novel processes have been developed for producing deuterium, 235 U, and the other separated isotopes that have become the fine chemicals of the nuclear age. The processing of radioactive materials, formerly limited mainly to a few curies of radium, is now concerned with the millions of curies of radioactive isotopes of the many chemical elements that are present in spent fuel discharged from nuclear reactors.

The preceding introduction to the preface of the first edition of this book can still serve as the theme of this second edition. Since 1957 nuclear power systems have become important contributors to the energy supply of most industrialized nations. This text describes the materials of special importance in nuclear reactors and the processes that have been developed to concentrate, purify, separate, and store safely these materials. Because of the growth in nuclear technology since the first edition appeared and the great amount of published new information, this second edition is an entirely new book,- following the first edition only in its general outline.

Chapter 1 lists the special materials of importance in nuclear technology and outlines the relationship between nuclear reactors and the chemical production plants associated with them. Chapter 2 summarizes the aspects of nuclear physics and radioactivity that are pertinent to many of the processes to be described in later chapters. Chapter 3 describes the changes in composition and reactivity that occur during irradiation of fuel in a nuclear reactor and shows how these changes determine the material and processing requirements of the reactor’s fuel cycle. Chapter 4 describes the principles of solvent extraction, the chemical engineering unit operation used most extensively for purifying uranium, thorium, and zirconium and reprocessing irradiated fuel discharged from reactors.

Chapters 5, 6, and 7 take up uranium, thorium, and zirconium in that order. Each chapter discusses the physical and chemical properties of the element and its compounds, its natural occurrence, and the processes used to extract the element from its ores, purify it, and convert it to the forms most useful in nuclear technology.

The next four chapters take up processing of the highly radioactive materials produced in reactors. Chapter 8 describes the isotopic composition and radioactive constituents of spent fuel discharged from representative types of reactors and deals briefly with other radioisotopes resulting from reactor operation. Chapter 9 describes the physical and chemical properties of the synthetic actinide elements produced in reactors: protactinium, neptunium, plutonium, americium, and curium, and their compounds. Chapter 10 describes the radiochemical processes that have been developed for reprocessing irradiated fuel to recover uranium, plutonium, and other valuable actinides from it. Chapter 11 describes conversion of radioactive wastes from reactor operation and fuel reprocessing into stable forms suitable for safe, long-term storage, and systems to be used for such storage.

The last three chapters deal with separation of stable isotopes. Chapter 12 lists the isotopes of principal importance in nuclear technology, discusses their natural occurrence, and develops the chemical engineering principles generally applicable to isotope separation processes. Chapter 13 describes processes useful for separating deuterium and isotopes of other light elements, specifically distillation, electrolysis, and chemical exchange. Chapter 14 describes processes used for separating uranium isotopes, specifically gaseous diffusion, the gas centrifuge, aerodynamic processes, mass and thermal diffusion, and laser-based processes.

Four appendixes list fundamental physical constants, conversion tables, nuclide properties, and radioactivity concentration limits for nuclear plant effluents.

As may be seen from this synopsis, this text combines an account of scientific and engineering principles with a description of materials and processes of importance in nuclear chemical technology. It aims thus to serve both as a text for classroom instruction and as a source of information on chemical engineering practice in nuclear industry.

Problems at the end of each chapter may prove useful when the text is used for instruction. References are provided for readers who wish more details about the topics treated in each chapter. Extensive use has been made of information from the Proceedings of the four International Conferences on the Peaceful Uses of Atomic Energy in Geneva, Switzerland, sponsored by the United Nations, which are listed as PICG, followed by the number of the conference, in the references at the ends of chapters.

This book was written in a transition period when U. S. engineering and business practice was changing from English to SI units. When the references cited used English units, these have been retained in the text in most cases. Equivalent SI values are also provided in many passages, or conversion factors are given in footnotes. In addition, conversion tables are provided in App. B. The multiplicity of units is regrettable, but it is unavoidable until the world’s technical literature has changed over completely to the SI system.

In preparing this text the authors have been blessed with assistance from so many sources that not all can be mentioned here. We are grateful to our respective institutions, Massachusetts Institute of Technology, University of California (Berkeley), and Hahn-Meitner-Institut (Berlin), for the freedom and opportunity to write this book. For help with calculations, illustrations, and typing, thanks are due Marjorie Benedict, Ellen Mandigo, Mary Bosco, Sue Thur, and many others. Editorial assistance from Judith B. Gandy and Lynne Lackenbach is acknowledged with gratitude. To the many generations of students who used the notes on which this book is based and helped to correct its mistakes we are greatly indebted. Among our more recent students we wish to thank Allen Croff, Charles Forsberg, Saeed Tajik, and Cheh-Suei Yang.

Among our American professional colleagues we are greatly indebted to Don Ferguson and his associates at Oak Ridge National Laboratory; Paul McMurray and others of Exxon Nuclear Company; James Buckham and Wesley Murbach of Allied General Nuclear Services; James Duckworth of Nuclear Fuel Services, Inc.; Joseph Megy of Teledyne Wah Chang Albany Company; Paul Vanstrum and Edward Von Halle of Union Carbide Corporation; Lombard Squires, John

Proctor, and their associates of E. I. duPont de Nemours and Company; Marvin Miller of MIT; and Donald Olander of the University of California (Berkeley). In Germany, we wish to thank Hubert Eschrich of Eurochemic, Richard Kroebel of Kemforschungszentrum Karlsruhe, Erich Merz of Kemforschungsanlage Julich, Walther Schuller of Wiederaufarbeitungsanlage Karlsruhe, and Eckhart Ewest of Deutsche Gesellschaft fur Wiederaufarbeitung von Kembrennstoff.

Assistance provided to one of the authors (MB) by a fellowship from the Guggenheim Foundation is acknowledged with gratitude.

Despite the valued assistance the authors have had in preparing this text, it doubtless still contains many errors and omissions. We shall be grateful to our readers for calling these to our attention.

Manson Benedict Thomas H. Pigford Hans Wolfgang Levi