Studies on the Control of Nuclear Materials by Spectroscopic Methods

Abstract

Generation of electric energy from controlled nuclear fission of heavy elements is the most important technical application of nuclear reactions at present time. This is attributed to the fact that the world's reserves of nuclear fuel materials including in particular uranium and thorium greatly exceed the existing reserves of coal, oil and gaseous products. In addition, the energy produced from nuclear fuel is in a far more intense and concentrated form than that from combustion of conventional fuels. Establishment of nuclear power industries based on fission reactors involves a number of materials including uranium, thorium, zirconium and heavy water, which acquired commercial importance only during the second half of the present century. To meet the ever increasing demand for nuclear materials, several novel chemical-engineering processes have been developed for separation and purification of uranium and eventually thorium, isotope separation and subsequent enrichment of fissile uranium- 235, and for separation of plutonium in reprocessing plants. Nuclear fuel consists mainly of fissile materials producing a net increase in neutrons when they absorb neutrons; and fertile materials producing fissile materials when absorbing neutrons. The principle fissile materials include uranium-235, plutonium-239 and uranium-233; while uranium-238, thorium-232, plutonium-240 and uranium-234 play the role of fertile materials. Among these uranium-235 is the only naturally occurring fissile material, in as much as 0.711 weight percent in uranium of natural isotopic composition. Selection of fuel materials for different nuclear reactors depends largely on the principal purposes for which the concerned facility may be used, whether for research activities, material testing, production of radioisotopes, massive production of plutonium or for power generation.