超临界水实验回路热工水力分析

作为超临界水堆失水事故分析的关键现象,跨临界过程(即超临界水堆的压力从超临界状态降到次临界状态22.1 MPa以下)受到国内外的关注。上海交通大学的超临界流体多功能实验回路(SWAMUP)计划对这一泄压过程进行实验研究。为确保该实验装置在实验过程中的安全性能,采用系统程序ATHLET-SC对该实验回路进行预计算分析,主要针对该系统在泄压跨临界过程中的热工水力参数,包括系统压力、冷却剂流量、加热棒壁面温度等展开计算,并讨论一些重要参数如泄压速度、加热棒加热功率等对计算结果的影响。计算结果表明,修改后的ATHLET-SC程序可模拟跨临界瞬态过程,在实验过程中,加热棒壁面温度不会超过设计上限温度,然而,回路中换热器的内外最高压差将会达6 MPa,这一点需在实验中特别考虑。

Thermal-hydraulic Analysis of SWAMUP Test Facility

Trans-critical transients, i.e. the pressure in the reactor system undergoing a rapid decrease from the supercritical pressure to the subcritical condition, are of crucial importance for the LOCA analysis of supercritical water cooled reactor (SCWR). To obtain more knowledge about this process, the supercritical water multipurpose loop (SWAMUP) test facility in Shanghai Jiao Tong University (SJTU) will be applied to provide test data for the process. Some pre-test calculations are necessary to show the feasibility of the experiment. In this study, the trans-critical transient analysis was performed for the SWAMUP test facility with the system code ATHLET-SC which was modified in SJTU. The system behaviors including system pressure, coolant mass flow, and wall temperature of heating rod during the depressurization were presented. The effects of some important parameters such as depressurization rate, heating power of heating rod on the system characteristics were also investigated. The results indicate that the revised system code ATHLET-SC is capable of simulating thermal-hydraulic behaviors during the trans-critical transient. According to the results, the wall temperature of heating rod during the transient is kept below the design limit. However, the pressure difference between the heat exchanger inside and outside after depressurization could reach 6 MPa, which should be considered in the test.