Investigation of neutronic and thermal–electric coupling phenomenon in a 100 kWe-level nuclear silent heat pipe-cooled reactor

Abstract

Heat pipe-cooled reactors are attractive because of their compact structure, high power capacity and reliability, and inherent safety features. These reactors are distinguished by the use of high-temperature heat pipes that directly bridge the reactor core and energy conversion devices, thus creating a tightly knit modular system. However, comprehensive coupled analysis of these reactors remains challenging because of the intricate multiphysics interactions involved. To address this, the neutronic and thermoelectric coupled phenomena of heat pipe-cooled reactors are investigated in this study. Models are introduced for the point reactor kinetics, core heat transfer, channel heat transfer, two-phase two-dimensional heat pipes, thermoelectric coupling, and cold plates. The channel heat transfer is refined in a 100 kWe-level nuclear silent heat pipe-cooled reactor and a model for the three-dimensional heat transfer process in its thermoelectric matrix established, which effectively resolves the calculation distortions of the lumped model. The maximum deviation between the calculation results from the proposed model and the verification data for a full-system coupled computation is less than 10 K. The core temperature difference from the three-dimensional model is five times that of the lumped model with a maximum average fuel temperature difference of 225.7 K. The maximum and average thermoelectric conversion efficiencies are 15.56 % and 14.43 %, respectively. The failures of one, five, and nine heat pipes are analysed. The failure of a single heat pipe has negligible effects with a peak fuel temperature surge of only 121 K. In contrast, a failure involving nine heat pipes leads to a peak fuel temperature spike of 778 K and a 47.1 % increase in the maximum heat transfer power, marking a critical operational threshold. It is therefore imperative to consider the safety margin in the potential failure of multiple central heat pipes during the preliminary design stages.