Applications of Fission and Fusion

In the next section, we examine fission and fusion and the industrial energy facilities designed to utilize them. 

The mass of a nucleus is less than the sum of the masses of its nucleons by an amount called the mass defect. The energy equivalent to the mass defect is the nuclear binding energy, usually expressed in units of MeV. The binding energy per nucleon is a measure of nuclide stability and varies with the number of nucleons in a nuclide. Nuclides with A == 60 are most stable. Lighter nuclei can join (fusion) or heavier nuclei can split (fission) to become more stable. 

Of the many beneficial applications of nuclear reactions, the greatest is the potential for almost limitless amounts of energy. Our experience with nuclear energy from power plants, however, has shown that we must improve ways to tap this energy source safely and economically. In this section, we discuss how nuclear fission and fusion occur and how we are applying them. 

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Sierk, A.J., Nix, J.R. Dynamics of fission and fusion with applications to the formation of superheavy nuclei. Los Alamos preprint LA-UR-73-981 (1973)... 

The tremendous release of energy from nuclear reactions makes possible a unique family of applications for long-lived radioisotopes that are important to health, science, and industry. Whereas fission and fusion occur almost instantaneously, other radioactive decay processes occur in times ranging from a few minutes to thousands of years. The general areas of application may be grouped into irradiation, thermal energy generation, and tracer applications.57... 

A primary objective of this work is to provide the general theoretical foundation for different perturbation theory applications in all types of nuclear systems. Consequently, general notations have been used without reference to any specific mathematical description of the transport equation used for numerical calculations. The formulation has been restricted to time-independent and linear problems. Throughout the work we describe the scope of past, and discuss the possibility for future applications of perturbation theory techniques for the analysis, design and optimization of fission reactors, fusion reactors, radiation shields, and other deep-penetration problems. This review concentrates on developments subsequent to Lewins review (7) published in 1968. The literature search covers the period ending Fall 1974. 

Inertial confinement fusion has long succeeded in the context of militai y explosions—the hydrogen bomb. In the militai y application a fission bomb produces x-rays that drive an implosion of D-T fuel to enormous temperatures and densities such that fusion reactions occur during the short time that inertia keeps the fusing nuclei densely packed and hot. 

Sensitivity functions provide the basis for a large variety of sensitivity studies. Sensitivity studies are becoming an important field in the application of perturbation theory. This is evidenced by the increasing number of papers published on this subject, which reached a high point in 1974 47, 48, 62, 66,68-80). This section sets out to describe (1) the principles of sensitivity and optimization methods that utilize sensitivity functions, and (2) potential uses for the application of perturbation-based sensitivity and optimization methods to fission reactors, fusion reactors and radiation transport problems. This is not intended to be a comprehensive review of either sensitivity or optimization methods, but rather an illustration of fields of application of perturbation theory formulations presented in Section V. Sensitivity and optimization studies not based on perturbation theory formulations are not discussed. 

A vast amount of energy is released when heavy atomic nuclei split—the nuclear fission process—and when small atomic nuclei combine to make heavier nuclei—the fusion process. In 1938, Otto Hahn, Fritz Strassman, Lise Meitner, and Otto Frisch discovered that ggU is fissionable by neutrons (Figure 13.8). In less than a decade, this discovery led to two important applications of this energy release accompanying fission—the atomic bomb and nuclear power plants. 

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