Fission reactor applications

This is a collaborative project between the countries participating in the NEA Data Bank. The JEF-2.2 library comprises sets of evaluated nuclear data, mainly for fission reactor applications it contains a number of different data types, including neutron interaction data, radioactive decay data, fission yield data, thermal neutron scattering raw data and photo-atomic interaction data. JEF-PC is a personal computer package containing selected data from the JEF 2.2 library. 

Ruffenach, J. C. 1978. Etude des migrations de l uranium et des terres rates sur une carotte de sondage et application a la determination de la date des reactions nicleaires. In Proceedings of the Technical Committee Meeting, Palis, 19-21 December 1975. Natural Fission Reactors, IAEA, Vienna, 441-471. 

Potential fusion applications other than electricity production have received some study. For example, radiation and high temperature heat from a fusion reactor could be used to produce hydrogen by the electrolysis or radiolysis of water, which could be employed in the synthesis of portable chemical fuels for transportation or industrial use. The transmutation of radioactive actinide wastes from fission reactors may also be feasible. This idea would utilize the neutrons from a fusion reactor to convert hazardous isotopes into more benign and easier-to-handle species. The practicality of these concepts requires further analysis. 

To adequately treat these many applications and to illustrate the specific ways in which decay data make useful, if not crucial, contributions to them is a task that lies beyond the space and time limitations of this paper. We have thus chosen to limit the scope of this presentation to the discussion of several selected examples, drawn mostly from the area of fission-reactor physics. These include the results of recent significant developments in actinide-nuclide decay data and, in the spirit of this symposium, decay data of fission-product nuclides off the line of p stability and some of the problems and challenges they present to both experimental capabilities and nuclear theory. 

A knowledge of the half-life is required for any application in which quantitative assay of material for radionuclide content is desired. In fission-reactor research and technology, for example, accurate half-life... 

Thereafter, cosmic rays were observed and explained, and many cosmic-ray-produced radionuclides were identified. The number of known and characterized radionuclides increased dramatically with the development and application of nuclear-particle accelerators in the 1930s and nuclear-fission reactors in the 1940s. 

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. 

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. 

This work is the first step in the process towards a unique data set which will be valid for all applications (core neutronics, shielding, fuel cycle) and for all types of fission reactors and consequently the integral data base needs to be enlarged. Complementary information on ERALIBl is given in ref. 3. 

Cylindrical reactor with source. An attempt is made here to describe the kinetics of a homogeneous cylindrical reactor with a point source of fast neutrons located at an arbitrary interior point on the axis of the reactor. The theory developed is quite general, at least to the extent that five delayed neutron groups are taken into consideration and appropriate ages are assigned to the source neutrons, the prompt fission neutrons, and each of five groups of delayed fission neutrons. Application of the theory is made to the problem of the determination of the power level in a so-called zero power critical assembly. 

The application of nuclear forensic techniques to samples of purified heavy elements is well developed however, when applied to unseparated spent reactor fuel, the methods become more complicated. The radionuclide content of a spent fuel sample is not controlled solely by radioactive decay, but is strongly influenced by neutron-induced transmutation. Chronometry based on the decay of the light plutonium isotopes cannot be performed due to the initial presence of an overwhelming quantity of uranium. The isotopic distribution of the plutonium isotopes and the concentration of fission products can provide a means by which the degree of transmutation can be estimated, unless the material started out as MOX fuel (where reprocessed plutonium is incorporated into fuel fabricated from uranium with insufficient fissile content to support the reactor application). More study is needed to extend the methodology to unprocessed fuel. 

Extensive research work has been going on for the safe disposal of radioactive wastes in different parts of the world, especially in the North American and West European countries where fission reactors are aplenty. Different types of clays and cl -derivatives are found to be more effective in safe disposal of different types of radioactive wastes. The clays are easily available than any other buffer materials, and the procedures of waste disposal with clay buffer are less expensive. This encoimages the researchers to explore further possibilities of application of cl s in this field. 

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