Empirical correlations for predicting the self-leveling behavior of debris bed

Empirical correlations for predicting the self-leveling

behavior of debris bed

CHENG Songbai1,* YAMANO Hidemasa1 SUZUKI Tohru1 TOBITA Yoshiharu1 NAKAMURA Yuya2 ZHANG Bin2 MATSUMOTO Tatsuya2 MORITA Koji2

【摘 要】Abstract Studies on the self-leveling behavior of debris bed are crucial for the assessment of core-disruptive accident (CDA) occurred in sodium-cooled fast reactors (SFR). To clarify this behavior over a comparatively wider range of gas velocities, a series of experiments were performed by injecting nitrogen gas uniformly from a pool bottom. Current experiments were conducted in a cylindrical tank, in which water, nitrogen gas and different kinds of solid particles, simulate the coolant, vapor (generated by coolant boiling) and fuel debris, respectively. Based on the quantitative data obtained (mainly the time variation of bed inclination angle), with the help of dimensional analysis technique, a set of empirical correlations to predict the self-leveling development depending on particle size, particle density and gas injection velocity was proposed and discussed. It was seen that good agreement could be obtained between the calculated and experimental values. Rationality of the correlations was further confirmed through detailed analyses of the effects of experimental parameters such as particle size, particle density, gas flow rate and boiling mode. In order to facilitate future analyses and simulations of CDAs in SFRs, the obtained results in this work will be utilized for the validations of an advanced fast reactor safety analysis code.

【期刊名称】核技术（英文版）【年(卷),期】2013(024)001【总页数】10

【关键词】Key words Sodium-cooled fast reactor, Core disruptive accident, Self-leveling, Debris bed, Gas injection, Empirical correlation

1 Introduction

The disaster in March 2011 at the Fukushima Dai-Ichi nuclear power plant in Japan makes more and more people to realize that severe accidents might occur, even if their probability is extremely low. In order to achieve In-Vessel Retention (IVR) for sodium-cooled fast reactors (SFR), the evaluation of core disruptive accident (CDA) has been one of the major concerns in the safety analyses during the past decades[1]. During a postulated