The reflood stage is an important stage after a large break loss of coolant accident(LBLOCA)in pressurized water reactor.In order to evaluate the simulation ability of the system code LOCUST,the verification and uncertainty research of LOCUST reflood model are carried out.Based on the experimental results of RBHT test bench,the LOCUST reflood model is verified.At the same time,the uncertainty of the reflood model is analyzed by response surface method,and the response function of the maximum temperature of the heating rod surface at three heights of RBHT test section is obtained by response surface method with the wall-liquid film boiling heat transfer coefficient,wall-vapor film boiling heat transfer coefficient and interface friction coefficient as input parameters.The calculated results are in good agreement with the experimental results,and the maximum temperature deviation is within 40 K.Based on the calculation results of response surface method,the maximum deviation of the maximum temperature of the heating rod surface at three heights is about 20 K with 95%probability and 95%confidence.Meanwhile,the highest temperature values calculated for the three heights are basically consistent with the experimental values when the dimensionless factors of the three input parameters are 1.951,1.233,and 0.1,respectively.