核反馈对并联双通道自然循环系统流动不稳定性的影响

将热工水力系统分析程序RELAP5与三维物理瞬态输运程序TDOT T采用并行方式耦合，对并联双通道自然循环系统内核热耦合不稳定性进行分析，得到系统的不稳定边界。分别以燃料时间常数差异较大的板型元件及棒型元件为对象，讨论了核反馈对系统稳定性的影响。对于板型元件，核反馈作用对低含汽率区的第1类密度波振荡（DWO）有明显的抑制作用，而对高含汽率区的第2类DWO基本无影响。对于棒型元件，计算分析结果表明核反馈对系统稳定性几乎无影响。

Effect of Neutronic Feedback on Flow Instability of Parallel Double-Channel Natural Circulation System

The thermal-hydraulic system code RELAP5 was coupled with the TDOT-T 3D neutron kinetic code by parallel virtual machine (PVM). A parallel double-channel natural circulation boiling system was built by the coupled code and the instability boundary of the system was obtained. Two types of fuel with different geometries (flat-plate-type fuel and pin-type fuel) were used in the analysis respectively, and the influences of neutronic feedback on density wave instability were analyzed. For the flat-plate-type fuel system, it is found that the type 1 density wave oscillation (DWO) is suppressed by neutronic feedback significantly but the effect of neutronic feedback on type 2 DWO is weak. For the pin-type fuel system, the result shows that the effect of neutronic feedback on instability boundary of the system could be ignored.