分类： 核科学技术 >> 核科学与技术 提交时间： 2024-03-21
摘要： Small-break superposed station blackout (SBO) accidents are the basic design accidents of nuclear power plants. Under the condition of a small break in the cold leg, SBO further increases the severity of the accident, and the steam bypass discharging system (GCT) in the second circuit can play an important role in guaranteeing core safety. To explore the influence of the GCT on the thermal-hydraulic characteristics of the primary circuit, RELAP5 software was used to establish a numerical model based on a typical pressurized water reactor (PWR) nuclear power plant. Five different small breaks in the cold-leg superposed SBO were selected, and the impact of the GCT operation on the transient response characteristics of the primary and secondary circuit systems was analyzed. The results show that the GCT plays an indispensable role in core heat removal during an accident; otherwise, core safety cannot be guaranteed. The GCT was used in conjunction with the primary safety injection system during the placement process. When the break diameter was greater than a certain critical value, the core cooling rate could not be guaranteed to be less than 100 K/h; however, the core remained in a safe state.
分类： 物理学 >> 核物理学 提交时间： 2023-08-10
摘要： Abstract To understand the dynamical system scaling (DSS) analysis theory, the applicability of DSS - and -strain transformation methods for the scaling analysis of complex loops was explored. A simplified model consisting of two loops was established based on the primary and secondary sides of a nuclear reactor, and - and -strain transformation methods were used to analyze the single-phase natural circulation in the primary circuit. For comparison with the traditional method, simplified DSS - and -strain methods were developed based on the standard scaling criterion. The strain parameters in these four methods were modified to form multiple groups of scaled-down cases. The transient process of the natural circulation was simulated using the Relap5 code, and the variation in the dynamic flow characteristics with the strain numbers was obtained using different scaling methods. The results show that both the simplified and standard DSS methods can simulate the dynamic characteristics of natural circulation in the primary circuit. The scaled-down cases in the simplified method exhibit the same geometric scaling and correspond to small core power ratios. By contrast, different scaled-down cases in the standard DSS method correspond to different geometric scaling criteria and require more power. The dynamic process of natural circulation can be simulated more accurately using the standard DSS method.
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