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AbstractAbstract
[en] In the model proposed in this paper, the reaction has been assumed to occur in two successive phases. In phase A a given number (function of time) of fuel particles comes in intimate contact with a given mass of liquid Na (function of time). The heat transfer process is characterized by very good direct thermal contact between the fuel and the liquid coolant, and by a large contact area due to the small size of the particles. The heat transfer coefficient decreases with time due to the formation of a temperature profile inside the fuel particles. The heated volume of sodium is constrained by the surrounding unheated coolant and by the other materials present in the core. The mechanical constraint is schematized by a sodium column of finite length which is contained in a channel located above the reaction volume. The sudden expansion of the heated volume first produces acoustic waves which travel along the sodium column. Later the sodium column behaves like a piston which is pushed inertially upwards. The pressure rises, reaches a maximum, and then falls as soon as the expansion of the liquid sodium becomes important. At the time which the pressure reaches the saturation point, sodium boiling starts and phase B begins. In phase B the heat transfer process now characterized by a very large contact area, and by a thermal contact between the fuel and the coolant which becomes increasingly worse with time, due to the formation of a sodium vapour layer at the external surface of the fuel fragments. The sodium will boil in a large quantity, and will produce therefore large volume changes. The sodium piston will be further accelerated and its movement will allow the pressure in the reaction volume to decrease. (Auth.)
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Source
Jaeger, T.A. (comp.) (Bundesanstalt fuer Materialpruefung, Berlin (Germany, F.R.)); International Association for Structural Mechanics in Reactor Technology; Commission of the European Communities, Brussels (Belgium); British Nuclear Energy Society, London; v. 2 p. E1/1 1-24; 1975; North-Holland; Amsterdam, The Netherlands; 3. international conference on structural mechanics in reactor technology; London, UK; 1 Sep 1975
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Book
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Conference
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