Analytical study of coupled neutronic and thermodynamic instabilities in a boiling channel

Abstract Linear stability analysis in the frequency domain is performed to reveal the basic mechanism of coupled nuclear-thermal instabilities in a boiling channel. It is found that the Ledinegg instability will not occur due to the coupling of the void-reactivity feedback and the hydrodynamic feedback. Besides the phase-change number Np and Jacob number Ja, the Froude number Fr and the fuel-time-constant τM are found to be the parameters determining the density-wave instability. It is also found that the Froude number effect on the density-wave stability becomes stronger when the void-reactivity feedback is involved, and that the lower the Fr number the less stable the system. The result reveals that there exists a region in which the void-reactivity feedback loop is unstable, and this has a strong effect on the stability of the system. A non-dimensional fuel-time-constant number is proposed, with which the stability boundary is better presented in the range of Froude numbers of interest.

[1]  Kenji Fukuda,et al.  Classification of two-phase flow instability by density wave oscillation model. , 1979 .

[2]  T. Fukahori,et al.  Space-dependent analysis of BWR core nuclear thermal hydraulic instability and thermal margin , 1990 .

[3]  L. Weaver.  System analysis of nuclear reactor dynamics , 1963 .

[4]  Jose March-Leuba,et al.  Coupled thermohydraulic-neutronic instabilities in boiling water nuclear reactors: A review of the state of the art , 1993 .

[5]  F. J. Moody,et al.  The thermal hydraulics of a boiling water nuclear reactor , 1977 .

[6]  Richard T. Lahey,et al.  The development of a closed-form analytical model for the stability analysis of nuclear-coupled density-wave oscillations in boiling water nuclear reactors , 1986 .

[7]  M. Becker,et al.  Frequency-Dependent Nodal Analysis of Boiling Water Reactor Stability , 1983 .

[8]  Fumimasa Araya,et al.  Analysis of a neutron flux oscillation event at LaSalle-2 , 1991 .

[9]  Richard T. Lahey,et al.  NUFREQ-NP: a computer code for the stability analysis of boiling water nuclear reactors , 1984 .

[10]  Richard T. Lahey,et al.  BWR linear stability analysis , 1986 .

[11]  Mamoru Ishii,et al.  Thermally induced flow instabilities in two-phase mixtures in thermal equilibrium , 1971 .

[12]  H. S. Cheng,et al.  BWR stability analysis at Brookhaven National Laboratory , 1991 .

[13]  Richard T. Lahey,et al.  Benchmarking and qualification of the NUFREQ-NPW code for best-estimate prediction of multichannel core stability margins , 1988 .

[14]  Masao Yokobayashi,et al.  Analysis of LaSalle-2 Neutron Flux Oscillation Event with RETRAN Code , 1992 .

[15]  Advances in the analytical modeling of linear and nonlinear density-wave instability modes , 1986 .

[16]  T. V. D. Hagen.  Experimental and Theoretical Evidence for a Short Effective Fuel Time Constant in a Boiling Water Reactor , 1988 .