Testing the feasibility of multi-modular design in an HTR-PM nuclear plant

Small modular reactors are the nuclear fission reactors with electric power output less than 300 MWe. To apply the enhanced safety of small modular reactors to build large-scale nuclear plants with any desired power ratings, the multi-modular scheme is recommended to be adopted, where multiple reactor modules are utilized to drive the common load equipment for power generation or cogeneration. The feasibility of multi-modular scheme is not verified until several plant-wide tests were carried out recently on the high temperature gas-cooled reactor pebble-bed module (HTR-PM) nuclear plant. The HTR-PM plant consists of two inherently safe nuclear reactors of 200 MWt, adopts the scheme of two reactor modules driving a common steam turbine, and operates commercially since December 6, 2023. In this paper, the responses of key process variables of HTR-PM plant in the tests of power ramping, turbine trip and reactor trip are provided, and the related multi-modular coordinated control method is also proposed. This result manifests the feasibility of multi-modular scheme practically, and shows the promising future of building large-scale nuclear plants with a system of small modular reactors.