Advances in Nuclear Science and Technology, Volume 5 presents the underlying principles and theory, as well as the practical applications of the advances in the nuclear field. This book reviews the specialized applications to such fields as space propulsion. Organized into six chapters, this volume begins with an overview of the design and objective of the Fast Flux Test Facility to provide fast flux irradiation testing facilities. This text then examines the problem in the design of nuclear reactors, which is the analysis of the spatial and temporal behavior of the neutron and temperature distributions within the system. Other chapters consider the three major ways of estimating shield effectiveness. This book discusses as well the purpose of variational principle, which is a characterization of a function as the stationary point of an appropriate functional. The final chapter deals with the solution of the Boltzmann transport equation. This book is a valuable resource for engineers.