Research on power regulation and distribution of the improved NHR200-II low temperature nuclear heating reactor

Abstract

Tsinghua University's low-temperature nuclear heating reactor (NHR) primarily focused on heating supply in its initial design. However, utilizing the reactor solely as a heat source limits its economic efficiency and competitiveness. To further broaden the application scope of the NHR200-II reactor, several modifications were implemented based on the original design. These include replacing the vertical steam generator with a horizontal one, which facilitates easier discharge of fouling, and add a superheater to enhance the thermal parameters values of the secondary loop to generate the desired superheated steam for industrial users. A comprehensive numerical modeling approach was employed to establish the primary loop, intermediate loop, secondary loop, and the passive residual heat removal system (PRHR) models for the NHR200-II reactor. The computational results indicate that the novel superheated steam supply system of the NHR200-II reactor exhibits good power control capability within the range of 50%–100% of the full power, with a step size of 10%. Moreover, the reactor demonstrates the ability to operate between 50% and 100% of the full power for a 24-h period, meeting the superheated steam demand of an industrial plant in a Chinese demonstration project. Furthermore, in the event of a reactor shutdown, the passive residual heat removal system efficiently removes the residual heat from the reactor core, thus preventing core meltdown accidents. The power between the reactor core and the superheated steam supply system could be well matched, and there could also be effective power distribution and coordination among the three heat exchangers. These numerical simulation results not only verify the new design of NHR200-II, but also contribute to the advancement of a demonstration project for a low-temperature nuclear heating reactor.