Tests of a Two-Stage Core at the KV-1 Test Facility: Physical Aspects and Results

Atomic Energy - The physical aspects and main results of reactor tests of a two-stage core consisting of fresh fuel assemblies and a significant number of fuel assemblies from the previous core,...     

Stability of Non-axisymmetric Electrolyte Jet in High-frequency AC Electric Field

In the present work linear instability of capillary non-axisymmetric micro-jets of electrolyte solutions in a high-frequency alternating axial electric field is investigated theoretically. The gravity affects are neglected. The problem is described by strongly coupled nonlinear system of PDEs for ion transport, electrical field and fluid flow. Viscous liquid is taken. The problem can be divided into outer and inner ones. Solution for the unsteady double ion layer is obtained in Debye-Huckel approximation provided that the oscillation frequency is sufficiently high while Pecklet number based on the Debye layer thickness is sufficiently small. The unsteady double ion layer produces additional normal and tangential stresses on the liquid–gas interface; the latter can either stabilize or destabilize the flow. It is shown that only axisymmetric mode is unstable while non-axisymmetric perturbations are always stable. It is also shown that in unstable case there is an essential dependence of the main stability characteristics on the parameter proportional to the frequency of external field. There are two threshold values of the parameter at which a bifurcation of stability parameters occurs. In particular, the size of the formed drops suffers a jump at increase of amplitude of fluctuation of an electric field. The problem is solved in a broad region of its parameters. There is a qualitative agreement of the theory developed with the available experimental data.     

Instability of Slender Liquid Jet in AC Electric Field of Arbitrary Frequency

In the present work stability of capillary micro-jet of electrolyte solution in alternating longitudinal electric field is investigated theoretically. The gravity effects are neglected. The problem is described by strongly coupled nonlinear system of PDEs for ion transport, electric field and fluid flow under assumption of a viscous Newtonian liquid. The Debye layer thickness is supposed to be small compared with initial jet radius. The Peclet number based on the Debye layer thickness is assumed to be small. These assumptions lead to substantial simplification of the problem. Slender-body theory is used to further simplification of initial statement. Used asymptotic method allows to reduce initially infinite system to three-dimensional ODE with time-periodic coefficients. It is shown that monodromy operator has the only real unstable multiplier. In the case of high-frequency alternating electric field the results showed good agreement with the ones provided by averaging theory.     

Flowrate monitoring in an RBMK process channel on the basis of coolant activity information

A method of determining the coolant flowrate in an RBMK process channel on the basis of activity information is examined. A mathematical model of coolant activation in the RBMK channel and an algorithm for determining the flowrate in the channel with an imprecise flowmeter are described. The results of tests of the computational-measurement system to determine the coolant flowrate in the No. 1 unit of the Kursk nuclear power plant are presented (area of application and error in flowrate determination).