Several emerging application areas are driving a revival in nuclear engineering, including new nuclear reactor designs (advanced water-cooled reactors, small modular reactors, and microreactors) and their various applications beyond electricity production and a revolution in nuclear medicine, nuclear space exploration, hydrogen production, and homeland security. This fully updated introductory textbook provides students and practitioners with the fundamentals of nuclear principles in engineering for a thorough understanding of physical processes relating to neutron physics, nuclear structures, and radiation interactions. To comprehend physical phenomena, hands-on computational exercises supported by mathematical details and real-life examples are provided to communicate the nuclear principles concepts. A new chapter details the evolution of nuclear power plants, explaining the modern-day technologies based on design details linked to the basic principles of nuclear engineering. In addition, every chapter is supplied with the problems solutions and answers. Nuclear Principles in Engineering, Third Edition, is written for students, engineers, physicists, and scientists who need up-to-date information on basic nuclear concepts and calculation methods, and will serve as an invaluable resource for training programs in the nuclear sector.