The Application of Nodal Kinetics to the Analysis of Coupled Neutronic/Thermohydraulic Phenomena

Abstract

This paper illustrates the application of Avery type nodal kinetics (1) to study the effect of neutronic feedback on coolant flow instabilities resulting from loss of pressure control in heat transport circuits without stabilizing interconnections. It is found that coolant flow and density oscillations occur at a frequency of 0.07 Hz with a phase separation of 180 degrees in the two passes of a figure-of-eight loop. The reactivity effects of the changes in coolant density, produce second harmonic oscillations in the neutron flux and in the components of the Reactor Regulating System. Neutronic feedback increases the oscillation amplitude by as much as 40% over the first 240 s.