小型可运输长寿命铅铋冷却快堆堆芯设计研究

Core Design Study of Small Transportable Long-life Lead-bismuth Cooled Fast Reactor

为满足偏远地区供电需求,提出了一种小型可运输长寿命铅铋冷却快堆(STLFR)堆芯设计方案,额定热功率为20 MW,在不换料条件下可运行18 EFPY(有效满功率年)。为减小堆芯体积,堆芯采用蜂窝煤型燃料组件,内设若干冷却剂管道,管外为燃料,实现了较高的堆芯燃料体积占比。为展平堆芯径向功率分布,将堆芯燃料区沿径向划分为三区,分别采用不同的冷却剂管道尺寸。为降低堆芯高度,设计使用含高富集度6Li的液态锂作为吸收体的液态吸收体控制系统。为降低初始剩余反应性,在堆芯控制组件与安全组件中布置两组固定式可替换吸收体,分别在堆芯燃耗1/3和2/3寿期时替换为固定式反射体。提出的堆芯设计方案在整个运行寿期内满足热工设计限值,控制系统和安全系统能独立满足堆芯控制和停堆要求。采用准静态反应性平衡方法对5种典型无保护事故工况进行分析,初步证明了堆芯具有固有安全特性。

In order to meet the demand of power supply in remote areas,a conceptual core design of a small transportable long-life lead-bismuth cooled fast reactor(STLFR)with rated power of 20 MW was proposed to operate for 18 EFPY(effective full power years)without refueling.In order to reduce core volume,the tube-in-duct(TID)fuel was proposed with coolant inside the tubes and fuel outside,which achieved a high fuel volume fraction in the core.For radial power flattening,the active core was divided into three regions radially with different sizes of coolant tubes.In order to reduce core height,a liquid absorber control system was implemented using 6Li-enriched liquid lithium as the neutron absorber.In order to lower the initial excess reactivity,replaceable fixed absorbers were installed in the control and scram assemblies,and then replaced by fixed reflectors at the 1/3 and 2/3 core lifetime.The thermal design constraints are satisfied during the whole life.The control system and safety system can independently provide sufficient shutdown margin.Five typical anticipated transients without scram were analyzed with the quasi-static reactive balance method,and the inherent safety characteristics of the core are demonstrated preliminarily.