Coordinated control of mHTGR-based nuclear steam supply systems considering cold helium temperature

Abstract

For industrial energy systems, there commonly exists coupling effect amongst those under-controlled process variables. Coordinated control of energy system enhances the operation performance by fully using the coupling effect positive to stabilization. Nuclear steam supply system (NSSS) module is the central of every nuclear plant, and the coordinated control of NSSS module is important for the stable, reliable and efficient operation of nuclear plants. Currently, the process variables considered in developing NSSS coordinated control strategies (CCSs) are mainly neutron flux, steam temperature as well as hot or average primary coolant temperature. Although cold primary coolant temperature, i.e. the primary coolant temperature at reactor inlet, reflects the heat balance between primary and secondary loops, it still not considered in developing CCS for NSSS modules. The modular high temperature gas-cooled reactor (mHTGR) uses helium as primary coolant and graphite as both moderator and structural material. Due to its inherent safety feature and high temperature, the mHTGR can be applied as a heat source driving industrial processes for power generation, chemical production and etc. To further improve the operation performance of mHTGR-based NSSS module, a passivity-based CCS is newly proposed by considering cold helium temperature. The sufficient condition for asymptotical closed-loop stability is given, and numerical simulation results in the cases of power stepping of 10 % reactor full power (RFP) as well as power ramping of 50%RFP and 5%RFP/min show that the control performance can be effectively improved.