AP1000核电厂二回路热循环冲洗方案

Flushing Scheme for Secondary Circuit Thermal Cycling in AP1000 Nuclear Power Plant

探讨了AP1000核电厂以凝结水泵作为动力源,单列加热器逐列投入的二回路热循环冲洗方案。通过热平衡计算分析,确定冲洗前辅助蒸汽的使用量;建立系统散热量计算数学模型,假设冲洗水温维持在60℃时,计算出小循环、大循环热冲洗阶段的总散热量,并与单台凝结水泵热功率进行了比较。计算结果表明,热冲洗过程中,不需要投入辅助蒸汽进行加热即可使冲洗水温稍高于60℃达到热平衡,此时系统总散热量和单台凝结水泵热功率相抵消。通过系统散热量的计算确定除氧器水箱温度变化趋势,给出避免凝汽器超温的措施。

The flushing scheme for secondary circuit thermal cycling was discussed in AP1000 nuclear power plant, in which condensate pump was used as a power source and single column heater was input one by one. At first, by means of the calculation of heat balance analysis, the usage amount of auxiliary steam before flushing was determined. Then, the mathematical model was built for heat dissipating capacity calculation with assumption that the temperature of flushing water was 60℃, the total heat dissipating capacity of small cycle and large cycle was calculated, as well as calculation results with the thermal power of single condensate pump were compared. The calculation results show that during the flushing process, the flushing water temperature can be slightly higher than 60℃ and reach the thermal equilibrium without auxiliary steam, and the thermal power of a single condensate pump can offset total heat dissipation. Finally, the change trend of water temperature in deaerator tank was presented through the calculation of heat release, and some measures for avoiding condenser over temperature were proposed.