Situations with local boiling of the coolant become more likely when VVER-type power units are transferred to a heightened power level. In a VVER core, neutron flux detectors are not present in all FA. An important problem for evaluating the possibility of detecting local boiling in FA which are not equipped with detectors is the study of the spatial distribution of the change brought about in the neutron flux noise by local boiling of the coolant. The results of an investigation of the spatial distribution of the neutron flux noise initiated by fluctuations of the coolant parameters at the ingress into the core with non-equilibrium local surface boiling are reported. The sensitivity of the neutron flux noise in FA with no boiling to local boiling in neighboring FA is analyzed. The results could be helpful in analyzing the data recorded by the in-reactor noise diagnostics system in commercial operation in operating power-generating units.

中文翻译：

---

基于中子通量噪声分析的VVER堆芯冷却液局部沸腾的空间效应研究

当将VVER型动力装置转移到更高的功率水平时，冷却剂局部沸腾的情况变得更有可能。在VVER堆芯中，并非所有FA中都存在中子通量检测器。评估未配备检测器的FA中局部沸腾的可能性的重要问题是研究冷却剂局部沸腾引起的中子通量噪声变化的空间分布。报道了中子通量噪声的空间分布调查结果，该中子通量噪声是由冷却剂参数波动引起的，其中冷却剂参数在进入非平衡局部表面沸腾堆芯时开始波动。分析了没有沸腾的FA中子通量噪声对相邻FA中的局部沸腾的敏感性。