Each steam generator (evaporator for short as following) of CPR1000 nuclear power unit is designed with four narrow range water level gauges and a wide range water level gauge, the measurement error or disturbance will affect the control of water level and when the low-low level of evaporator appears the reactor will trip, the primary loop and the secondary loop will cross, also the reactor core has the risk of losing cooling under serious condition. In the paper, we will take the example of the evaporator water level’s abnormal fluctuation for several times of a certain nuclear power unit during the start or stop phase, and refer to the measuring principle of differential pressure type water gauge, to discuss the cause of the water level fluctuation , and to optimize the water level measurement with the nuclear grade intelligent transmitter in CPR1000 nuclear power unit ,as well as to optimize the improvement plan and measures, according to the design and installation.%CPR1000核电机组每台蒸汽发生器（简称蒸发器）设计有4台窄量程水位计和1台宽量程水位计，其测量偏差或扰动将影响蒸发器水位控制或产生蒸发器水位低触发反应堆跳堆保护，严重工况下存在一二回路贯通、堆芯失去冷却等风险。本文结合国内某核电站三、四号机组在机组启、停阶段多次出现的蒸发器水位异常波动的典型实例，结合差压式水位计测量原理，阐述了水位波动的根本原因。同时从设计安装改进的维度提出了核级智能变送器在CPR1000核电机组中水位测量的优化、改进方案及措施。
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