火箭推进

核热推进系统不仅要像传统动力堆产生预期功率,还需具备快速启动与推力调节的能力,以满足其变轨与机动的需求。因此,瞬态分析对于核热推进系统的方案设计、运行策略和集成试验等有重要作用。以颗粒床反应堆燃料组件为研究对象,建立了一维瞬态热工水力模型,并分析了功率提升过程以及反应性引入后的响应特性。研究发现由于颗粒床反应堆热量载出能力强,且燃料颗粒自身热容小,因此在启动等瞬态过程中换热滞后现象较弱,从而避免了堆芯内由于蓄热效应显著可能造成的超温或热应力过大等现象,有利于实现快速启动。额定工况下引入阶跃反应性,冷却剂载热滞后于堆芯释热约0.1 s,同样有利于系统功率和推力的快速调节。此外,颗粒床反应堆堆芯阻力会随着功率升高而增大,因此在启动和推力调节等过程中需要进一步研究反应性引入与推进剂供应量的匹配技术,以实现核热推进系统的运行与控制。

To achieve orbit transfer and maneuver, the nuclear thermal propulsion(NTP)system should not only release the expected heat like the traditional power reactor but also have the capability of rapid start and thrust regulation. Therefore, transient analysis is important for system design, operation strategy, and integrated test of NTP. In this paper, a one-dimensional transient thermal hydraulics model of the Particle Bed Reactor(PBR)fuel assembly was established and the response performance was analyzed under a condition of power raising. It was observed that during the start-up procedure, the delay between heat transfer on the particle surface and heat release in the fuel kernel was minimal due to the strong heat removal by the coolant and the low heat capacity of the fuel particle. The effect prevented the over temperature and high thermal stress resulted from thermal storage, which benefits the rapid start. Under rated operating conditions, introducing a reactivity step change results in a thermal response that delays behind the variation in neutron density by about 0.1 s, which also benefits the system power and thrust rapid adjustment. Furthermore, the PBR core resistance rapidly increases with the elevation of core power. Therefore, further research is needed to optimize the matching of reactivity insertion and propellant supply during startup and thrust regulation processes. This study can inform the operation and control strategies of nuclear thermal propulsion systems.

引言
1 燃料组件简化模型
2 燃料颗粒传热模型
3 组件瞬态分析流程
4 结果与讨论
5 总结与展望

图1 颗粒床反应堆概念示意图<br/>Fig.1 Schematic view of the particle bed reactor

图1 颗粒床反应堆概念示意图
Fig.1 Schematic view of the particle bed reactor

图2 颗粒床反应堆燃料组件简化过程示意图<br/>Fig.2 Simplified process of the particle bed reactor fuel assembly

图2 颗粒床反应堆燃料组件简化过程示意图
Fig.2 Simplified process of the particle bed reactor fuel assembly

图3 燃料颗粒模型示意图<br/>Fig.3 Schematic view of the fuel particle model

图3 燃料颗粒模型示意图
Fig.3 Schematic view of the fuel particle model

图4 一维燃料组件瞬态热工水力分析流程图<br/>Fig.4 Flow chart of transient thermal-hydraulic analysis of one-dimensional fuel assembly

图4 一维燃料组件瞬态热工水力分析流程图
Fig.4 Flow chart of transient thermal-hydraulic analysis of one-dimensional fuel assembly

表1 颗粒床燃料组件主要几何设计参数<br/>Tab.1 Geometry and thermal parameters of the particle bed fuel assembly

表1 颗粒床燃料组件主要几何设计参数
Tab.1 Geometry and thermal parameters of the particle bed fuel assembly

表2 燃料颗粒主要设计参数参数<br/>Tab.2 Main parameters of the fuel particle

表2 燃料颗粒主要设计参数参数
Tab.2 Main parameters of the fuel particle

图5 燃料颗粒内释热与颗粒床表面换热变化情况<br/>Fig.5 Volumetric heat deposition and surface heat removal by coolant

图5 燃料颗粒内释热与颗粒床表面换热变化情况
Fig.5 Volumetric heat deposition and surface heat removal by coolant

图6 颗粒床内推进剂与颗粒平均温度变化情况<br/>Fig.6 Mean temperature of the propellant and the fuel particle in the bed

图6 颗粒床内推进剂与颗粒平均温度变化情况
Fig.6 Mean temperature of the propellant and the fuel particle in the bed

图7 燃料组件质量流量变化情况<br/>Fig.7 Mass flow rate in the fuel assembly

图7 燃料组件质量流量变化情况
Fig.7 Mass flow rate in the fuel assembly

表3 缓发中子参数[14]<br/>Tab.3 Parameters of delayed neutron[14]

表3 缓发中子参数[14]
Tab.3 Parameters of delayed neutron[14]

图8 额定工况下引入0.2$反应性各参数响应<br/>Fig.8 The response of various parameters to the insertion of 0.2$ reactivity under rated conditions

图8 额定工况下引入0.2$反应性各参数响应
Fig.8 The response of various parameters to the insertion of 0.2$ reactivity under rated conditions

图9 额定工况下引入-0.5$反应性各参数响应<br/>Fig.9 The response of various parameters to the insertion of -0.5$ reactivity under rated conditions

图9 额定工况下引入-0.5$反应性各参数响应
Fig.9 The response of various parameters to the insertion of -0.5$ reactivity under rated conditions

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备注

引言

1 燃料组件简化模型

2 燃料颗粒传热模型

3 组件瞬态分析流程

4 结果与讨论

5 总结与展望

期刊信息