COUPLED NEUTRONIC-THERMAL-HYDRAULIC ANALYSIS OF A SMALL FHR CORE WITH PIN-TYPE FUEL ASSEMBLIES

摘要

This study undertook a coupled neutronic-thermal-hydraulic analysis of a small fluoride salt-cooled high-temperature reactor (FHR), one of the advanced Gen. Ⅳ concepts. The objective is to further investigate the practical feasibility of two UO_2 pin-type fuel assembly designs, namely 3- and 4-ring designs, by looking primarily at thermal-hydraulic (TH) parameters, such as linear power and fuel centreline temperature, as well as radial power peaking. The coupled neutronic-TH analysis was performed by the external coupling of Serpent, a Monte Carlo based reactor physics code, with the TH feedback provided by THERMO. Sensitivity analysis was performed by varying the fuel pin radius by ±5% and ±10% of its original size. Results show that the 4-ring design has better TH performance than the 3-ring design. However, this TH advantage is outweighed by the superior neutronic performance offered by the 3-ring design. The change in fuel pin radius does not significantly affect fuel centreline and coolant temperatures for either design, but the discharge burnup and pressure drop increase with increasing fuel pin radius.