Neutron radiography has in recent years emerged as a useful and complementary technology for radiation diagnosis. It is now routinely used in industrial quality assurance and in support of selected research and developmental activities. Conferences are held on the subject, pertinent handbooks exist, and technical papers appear regularly reporting on new developments. While neutron radiography has indeed passed through the transition from a scientific curiosity to technological relevance, it is a sign of its continuing dynamic evolution that little material has appeared which provides an integrated mathematical and physical analysis of the subject possessing both an instructional as well as reference function. It is our hope that this monograph will fill this need. The distinctiveness of neutron radiography rests on the unique interactions between neutrons and nuclei. This leads to some special relationships between the material and geometrical properties of an object and the neutron radiographic image. The evolution of a technical discipline demands that specific conceptual constructs be developed and their mathematical representations examined and compared with controlled experiments. Experience has convinced us that a particular and substantial body of knowledge has accumulated endowing neutron radiography with the essential foundations of a unique mathematical and physical science. Our scientific and professional involvement in neutron radiography began some 15 years ago when the senior author (A.A.H.) found himself with convenient access to the McMaster University Nuclear Reactor and research support from the Government of Canada.

Neutron radiography has in recent years emerged as a useful and complementary technology for radiation diagnosis. It is now routinely used in industrial quality assurance and in support of selected research and developmental activities. Conferences are held on the subject, pertinent handbooks exist, and technical papers appear regularly reporting on new developments. While neutron radiography has indeed passed through the transition from a scientific curiosity to technological relevance, it is a sign of its continuing dynamic evolution that little material has appeared which provides an integrated mathematical and physical analysis of the subject possessing both an instructional as well as reference function. It is our hope that this monograph will fill this need. The distinctiveness of neutron radiography rests on the unique interactions between neutrons and nuclei. This leads to some special relationships between the material and geometrical properties of an object and the neutron radiographic image. The evolution of a technical discipline demands that specific conceptual constructs be developed and their mathematical representations examined and compared with controlled experiments. Experience has convinced us that a particular and substantial body of knowledge has accumulated endowing neutron radiography with the essential foundations of a unique mathematical and physical science. Our scientific and professional involvement in neutron radiography began some 15 years ago when the senior author (A.A.H.) found himself with convenient access to the McMaster University Nuclear Reactor and research support from the Government of Canada.

This book is intended as an introductory exposition of those nuclear energy systems concepts which are characterized by an integrated utiliz ation of complementary nuclear processes. Basic to such systems is the notion of synergism, which herein implies the cooperative interaction of selected nuclear reactions and system components so as to provide overall advantages not possible otherwise. While the concept of nuclear energy synergism has in recent years become the focus of an increasing number of conferences, scientific papers, and institutional in-house reports, no text which encompasses the major topics of the subject at a conceptual and analytical level has appeared. It is our aim to present a systematic characterization of these emerging nuclear energy concepts suitable for the senior university student of nuclear science and engineering as well for the active pro fessional involved in nuclear energy systems planning and analysis. In addressing the subject of nuclear energy synergism we have become most conscious of the tension between realism and vision in nuclear energy technology. As developed here, our perception of nuclear energy synergism is firmly rooted in the present and then seeks to proceed toward a heightened degree of compatibility and efficacy based on an enhanced integration of relevant nuclear processes. It is our view that such conceptual considerations must assume a greater role in the emerging techological orientation of nuclear energy systems planning.

In March 1981 the International Institute for Applied Systems Analysis (IIASA) published the results of a global energy study looking fifty years into the future: Energy in a Finite World: A Global Systems Analysis (Cambridge, Massachusetts: Ballinger Publishing Co., 1981)*. Not surprisingly, this book raises almost as many questions as it answers; thus, it defines a broad range of research topics that might be taken up by IIASA or other research institutions around the world. A 25-27 May 1981 workshop at IIASA entitled "A Perspective on Adaptive Nuclear Energy Evolutions: Towards a World of Neutron Abundance" was a beginning on one of these topics; it was organized by Wolf Hafele (Kernforschungsanlage Ji. ilich, Jiilich, Federal Republic of Germany, and IIASA) and Arkadius Archie Harms (McMaster University, Hamilton, Ontario, Canada). The origin of this workshop was the effort with in the IIASA energy study to explore possible "sustainable" global energy systems that might eventually replace the current "consumptive" system. In investigating the possible contributions nuclear technologies might make to a sustainable energy system, it had become clear that it is not so much particular, distinct technologies within the nuclear family that should be examined as a question of particularly advantageous configurations of mutually complementary technologies. Only when one considers exploiting a whole spectrum of arrangements of fission breeders, fusion reactors, and accelerators does the true potential of nuclear power become apparent."