小型双流熔盐铅基堆的无棒系统稳定性机理及其控制

The dual-fluid molten salt reactor (DFR) belongs to the novel GEN-IV fast reactor, which utilizes UCl3+PuCl3 mixture as the fuel and liquid lead as coolant. Compared to other molten salt reactors, the DFR has a larger negative temperature feedback coefficient. Since the DFR does not have the control rods, the reactivity needs pumps, valves and other components to regulate. Including but not limited to, an assembly of such measurements is called the stability control system without control rods...The project firstly establishes a parameter databank for the components in the system, which may have impact to the stability of the system, analyses the stability mechanism of the system. Secondly, the project models the effect of the components in the small DFR to the system stability, then evaluates the stability of the system without control rods by using the coupled model of deterministic and stochastic Monte Carlo methods with the CFD method. The control system without control rods for the small DFR will be modeled and analyzed. During this process the stability mechanism of the system without control rods will be mastered, and the model of the control system will be complete. Thirdly, this mechanism will be applied in multiple operations to be tested in the aspects of power and operational status, the static and transient analysis of the system will be performed. At last, the feasibility of the system stability by using this mechanism in the DFR to maintain the stability of the system will be discussed, while the problems that would be possibly introduced will also be discussed. The final solution of the stability control of the small DFR will be given.

双流熔盐铅基堆（双流堆）属于第四代新型快中子堆，使用氯化铀/钚混合熔盐为燃料，熔融铅为冷却剂。相对其他熔盐堆，该反应堆有着更强的负温度反馈系数，且由于没有控制棒，其反应性需要借助泵、阀门等系统组件和部件来进行调节。包括但不限于这些手段的反应性调节方式可以被视作无棒系统稳定性控制。.本项目首先建立小型双流堆无棒系统中对稳定性起影响作用的组件、部件的参数数据库，分析系统稳定机理。其次针对组件对系统稳定性的影响建模，采用确定性分析模型与蒙特卡洛方法-CFD方法耦合模型对无棒系统的稳定性开展模拟计算，掌握无棒系统稳定机理，完成小型双流堆无棒控制系统的建模和理论分析。再次，在多工况下通过该控制系统进行系统功率与运行状态转换的模拟计算，开展系统稳态/瞬态的控制响应。最后，论证在小型双流堆中使用该控制方案实现系统稳定的可行性，探索和讨论可能带来的问题，提出适合于小型双流堆的无棒系统稳定性的最终控制方案。

小型双流熔盐铅基堆无棒系统的稳定性机理及其控制这一问题对完善核反应堆稳定性控制理论有着切实的科学意义，对小型双流熔盐铅基堆的推广及应用具有明确的现实意义。本项目针对小型双流熔盐铅基堆无棒系统稳定机理问题，建立了能准确反映物理学特性的组件参数数据库；根据堆内物理现象时间上的随机性与空间上的非均匀性，基于蒙特卡罗中子物理计算程序和开源热工流体模拟程序构建了小型双流熔盐铅基堆无棒系统的子通道和堆芯等多层次的中子物理与热工水力耦合模型并完成了多工况验证，掌握了在不同几何、系统配置条件下无棒系统的控制机理；基于Modelica语言提出了小型双流熔盐铅基堆无棒系统在一维集总参数核动力系统中的稳定性控制方案，获得了系统的稳态/瞬态响应，针对不同工况给出了具体控制手段和基于此的安全分析，验证了控制方案设计的有效性和稳定性。