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METALS AND NUCLEAR ENERGY
Many of the problems with which metallurgists have to meet in the development of nuclear energy are connected with the peculiar behaviour of metallic nuclear fuels. Until now the fuel of nearly every reactor constructed has been uranium metal. Uranium is a highly reactive metal of complex structure (in its alpha and beta forms) and new problems appeared when it was set to work in reactors operating at a temperature where oxidation was rapid, where there were high neutron fluxes and where the temperature varied in an irregular way.
In the early stages, the metallurgist's problem was to produce the metal suitably protected and in a satisfactory structural condition to withstand periods of several months in the reactor without failure. The purpose of the early American reactors built during the war was to produce plutonium for military purposes, and, as soon as it became available in sufficient quantities, the metallurgical properties of that metal had to be investigated.
Later the field of work has been enlarged to the point where success or failure of a reactor project depends upon the satisfactory solution of metallurgical problems. For power production, the nuclear fuel must be able to withstand much higher neutron doses than in early plutonium-producing piles. As will be seen later, unalloyed uranium cannot be quite satisfactory for such reactors, and the metallurgist must investigate alloy structure and mechanical and physical characteristics in relation to irradiation behaviour.
New metallurgical problems arise with the introduction of better methods of heat removal. High-pressure water and sodium are examples of heat-transfer media which will be important in the next phase of power development. In both cases problems of corrosion have to be solved.
The new types of reactor operating at high ratings need a wide variety of sheathing materials, and both the chemical and physical interactions of these with the fuel have been extensively investigated. The use of new materials has also called for work on their fabrication and joining characteristics.
Nuclear energy has produced a new tool for metallurgical work in the form of neutron diffraction (which has been used particularly on the problem of antiferromagnetism). Progress in the production of electricity by the utilization of nuclear energy is limited at present more by the rate at which improved materials, especially better fuel elements, can be developed than by the rate of extension of reactor physics.
2. Find in the text English equivalents to the following words and word combinations:
ядерна енергія, ядерне паливо, уран, поломка, військові цілі, залежати від, задовільне вирішення, обшивка, хімічна та фізична взаємодія, виробництво, властивості з’єднання, нейтронові дифракції.
3. Find in the text antonyms to the following words:
regular, unsatisfactory, to be free from, slow, to be widen.
4. Make up word combinations from the following words:
nuclear, condition, complex, reactive, sufficient, military, metal, structure, metallurgical, satisfactory, purposes, physical, energy, quantities, problems, characteristics.