Thermal-Hydraulic Stability Analysis Method

The one-dimensional single-channel single-phase conservation equations of mass, energy and momentum, and the state equation for the coolant channel are written 

The conservation equations are numerically discretized along the axial direction by the forward finite difference method. The discretization or nodalization is done by dividing the coolant channel and the water rods into nodes of equal length and by approximating the time-dependent thermal-hydraulic variables as spatially uniform within these nodes. Equations (5.36)-(5.39) are expressed as follows for each axial node i. 

These equations are perturbed, linearized, and Laplace-transformed from the time domain to the frequency domain to evaluate the transfer functions between various thermal-hydraulic parameters. The Laplace-transformed equations are solved simultaneously by means of a matrix equation. 

For the single-phase region, the state equation becomes 

The mixture density and the mixture specific enthalpy are defined as 

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Coupled Neutronic Thermal-Hydraulic Stability Analysis Method... 

Like in the thermal-hydraulic stability analyses, the frequency domain analysis method is used here, too. The mathematical model contains six submodels - the neutron kinetics model, the fuel rod heat transfer model, water rod heat transfer model, fuel channel thermal-hydraulic model, water rod thermal-hydraulic model, and the excore circulation system model. The fuel channel thermal-hydraulic model and water rod thermal-hydraulic model are the same as the thermal-hydraulic stability analysis model described in Sect. 5.4.3. 

Chapters 3-5 treat the plant system and behaviors. They include system components and configuration, plant heat balance, the methods of plant control system design, plant dynamics, plant startup schemes, methods of stability analysis, thermal-hydraulic analyses, and coupled neutronic and thermal-hydraulic stability analyses. 

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