Extension of Load Follow Operation of PWRs Without Boron Adjustment

Abstract

Due to development of electric power system, the proportion of nuclear power and its needs for Load follow operation have become large. Then there would be higher requirements to the power control ability of the nuclear power system. The project with China’s own brands and using the advanced pressurized water reactor (APWR) nuclear power technology, CPR1000, adopts a control method called Mode G, using G banks, N banks, R bank and soluble boron to perform the load follow control. The common Point Model, widely used in conventional core modeling, cannot successfully research the axial power distribution. But in this paper, a two-node dynamic function model was built, taking CPR1000 as an example, considering the coupling coefficient and mutual influence. The transient parameter values were obtained by the steady-state calculation of single channel with its original structure parameter and operation parameter. Then the core system simulation of CPR1000 was modeled. In order to carry out the load follow operation without the boron adjustment, known as BTP mode, the control banks were regrouped to control the average temperature by M banks and axial offset by AO bank. The last, the optimal control implementation was connected to the core simulation platform to operate with the variable daily load. The feasibility and effectiveness of the control policy and the simulation system are validated by the calculation results via one-dimensional in axial computer code APOC. Results of computations performed for a reference reactor were present, giving the possibility that the optimal control policy could stretches the capability of the reactor to follow an average daily load curve. The paper demonstrated in principle that the BTP mode was feasible for CPR1000.