Scaling criteria for modeling natural- and forced-convection loops. [PWR]

Nuclear reactor safety regulations have required extensive thermal-hydraulic testing of simulated reactor systems and components. In view of the inherent difficulties associated with full-scale testing, scale models for prototype systems have been extensively used to predict the behavior of nuclear reactor systems during normal and abnormal operations as well as under accident conditions. Several studies have been performed to establish similarity relations between a prototype and scale model. It is the purpose of the present study to develop scaling criteria for a forced and natural circulation loop under single- and/or two-phase flow conditions, and to apply the criteria to obtain the preliminary conceptual design parameters for the B and W 2 x 4 loop system. The 2 x 4 loop scaled system contains representative components of all thermal-hydraulic systems considered important in performing tests to obtain data representative of the response of the prototype plant

General formulation of an HCDA bubble rising in a sodium pool and the effect of nonequilibrium on fuel transport

This report which improved the formulation of the previous reports is designed to investigate the effect of the interfacial nonequilibrium mass transfer and the radiative heat transfer on the amount of the fuel vapor condensed before the bubble reaches to the cover-gas region. Consideration is given to a fuel dominated bubble which is assumed to have just penetrated into the sodium pool in a spherical form subsequent to an Hypothetical Core Disruptive Accident (HCDA). The two-phase bubble mixture as it rises through the sodium pool to the cover-gas region is formulated. The formulation takes into account the effects of the nonequilibrium mass transfer at the interfaces and of the radiative cooling of the bubble as well as the kinematic, dynamic and thermal effects of the surrounding fields. The results of calculation for the amount of the fuel vapor condensed before the bubble reaches the cover-gas region are presented over a wide possible range of the evaporation coefficient as well as the liquid sodium-bubble interface absorbtivity

Local phase distribution and interfacial area in a horizontal bubbly two-phase flow

Short communication