Simulations of Coupled Core and Steam Generator Dynamics (Contribution to Task 4.4: “Preliminary definition of the Control Architecture” Status Report). Bologna, 26 th October, 2011. Authors:Dumitru Dobrea , Laurentiu Aioanei. 1. Introduction.
Simulations of Coupled Core and Steam Generator Dynamics(Contribution to Task 4.4: “Preliminary definition of the Control Architecture” Status Report)
Bologna, 26th October, 2011
Figures present a comparison between the results obtained with constant =1/2 for both sub-cooled and superheated regions and the results obtained with computed with the iterative procedure, when coolant flow rate is stepwise increased by 10%.
Non-Linear System Simulations with constant
Water Flow Rate 10% Step Increase
SG Inlet Water Temperature 1 with constant oC/s in 10 s Ramp Increase
Turbine Admission Coefficient 10% Step Increase with constant
Reactivity Step Increase by 20 pcm with constant
Linearized System Simulations with constant
Turbine Admission CoefficientStep Increaseby 1%
Lead Flow Rate 1% Step Increase with constant
SG Water Inlet Temperature with constant 1oC/s in 10 seconds RampIncrease
1% Water Flow Rate Step Increase with constant
20 pcm Reactivity Step Increase with constant
Output Variation for Reactivity Step Increase by 20 pcm with constant
The figures below are examples of control applied to lead outlet temperature and core power as outputs when control rod reactivity is used as step input for core dynamics. The controlled parameters are normalized to one both in free and closed loops.
1. By adapting the MVB model using an enthalpy averaging procedure to satisfy the imposed value of SG tube, the simulation results of the non-linear dynamics of coupled SG and core do not deviate significantly from those reported in ref. , as regarding final steady-states. As regarding shape, including peak heights, comparisons could pe performed based a common set of heat transport core-SG and pump. Most important differences at final steady-state could be observed for coolant flow rate variation. But the final values are close to initial values and slight differences in thermophysical data or correlations for water and lead could produce the deviations.
2. The linearized model results fit well the non-linear results for 1%, or 1 oC input variations for all transients, except turbine admission coefficient variations, where several percent deviations persist at very small input variation. This issue may be further investigated.
3. Restricting the range of heat transport time constants and working with actualized values of reactivity coefficients (for ALFRED) would be desired.
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