Dynamic thermal performance analysis for fin-concrete ceiling in main control rooms of passive nuclear power plants

The main control rooms of passive nuclear plants must maintain a habitable environment once station-blackout accidents occur. In this condition, the heavy fin-concrete ceiling on the room will remove heat from kind of heat sources and protect from overheating environment. However, the dynamic thermal process of finned concrete ceiling has not been studied in various passive cooling measures. In this study, an efficient parametric resistance-capacitance thermal network model is established to describe dynamic thermal responses of heavy fin-concrete layer, and validated by dynamic temperature change data of a hot-box experiment for 24 h. Series indicators were deduced by analytic solutions. Based on the validated model and indicators, factor analysis was conducted to obtain details of effect of finned-plate geometric parameters and heat source intensity. The results show that initial 2-h thermal process can be divided into two stage, "transient stage" and "quasi-stable stage". The transient-stage thermal process is determined by source flux and finned coefficient of finned plate. The quasi-stable thermal process depends on thermal mass of the finned plate and heat source flux. Furthermore, there exists a linear relationship between air temperature and heat source flux. Finned plate layout can be design according to the factor assessment results.