体热源沸腾池的建模及其验证

在事故保护系统和自动停堆系统失效的假设下,快堆中一大类事故可能会发展到熔融池和沸腾池阶段,此阶段的特征是:液态钢和液态燃料为池内主要成分,以燃料的裂变热为体热源,整个池子被附着在冷壁面上的UO2固化壳包裹,当其中钢的温度超过沸点时,便开始沸腾。建立了一个半经验模型来描述体热源沸腾池的行为。模型中,用漂移速度模型来预测空泡份额分布,用修正后的Greene关系式计算平均传热系数并在此基础上根据实验结果确定局部传热系数,用焓方法求解包裹沸腾池的固化壳的温度场及厚度。对SCARABEE BF2实验(单组分UO2沸腾池)及BE+2(UO2 钢混合沸腾池)进行了模拟计算,计算结果与实验结果基本吻合。

Modeling of volume heated boiling pool and its validation

Under the assumption of failure to scram, a large variety of accidents may cause the formation of a volume heated boiling pool in a fast breeder reactor. Generally speaking, the pool is made up of liquid steel and liquid UO 2 , heated by fissile heat and bounded by UO 2 crust that froze on cold surface. When liquid steel reaches its saturation temperature, it will boil up. A simple semi-empirical model was developed to predict its behavior. In the model, the distribution of void fraction was calculated by drift flux model; local heat transfer coefficient was determined by experimental results and average heat transfer coefficient, which was calculated by modified Greene correlation; the temperature field and thickness of UO 2 crust was obtained by solving enthalpy model. Calculations for SCARABEE BF2 experiment (single component UO 2 boiling pool) and BE+2 experiment (UO 2 and steel mixed boiling pool) were performed, the results approximately agree with the experimental observation.