Thermal Hydraulic Design and Evaluation of the Solid Microencapsulated Fuel in Light Water Reactors

Solid Microencapsulated Fuel (SMF) is a kind of solid fuel rod design that disperses TRISO coated fuel par-ticles directly into a kind of matrix. Without cladding tube and associated failure mechanisms, this type of new fuel design is expected to provide improved performance under normal and even accident condi-tions. The purpose of this paper is to analyze the thermal hydraulic performance of SMF based on a single channel, compared to the traditional fuel in the 200 MW Nuclear Heating Reactor (NHR200-II). Two kinds of specific SMF by dispersing TRISO particles into Zirconium or SiC matrix were investigated. Thermal margin to DNB was assessed and confirmed by determining the heat transfer capacity under normal con-dition. Two-phase pressure drop was evaluated by using the homogeneous equilibrium boiling assump-tion. The centerline temperature of SMF rod was calculated by using effective thermal conductivity of two-phase composite. The analysis of flow instability and flow-induced vibration were also included and compared. This study showed that SMF has a better thermal transfer capacity, a higher margin from vortex shedding and fluid-elastic instability, and a lower fretting wear rate, while a higher sliding wear rate because of a higher Young's modulus and fundamental frequency, which is compensated by a higher hardness for SiC matrix.(c) 2022 Elsevier Ltd. All rights reserved.