某核电厂蒸汽发生器液位测量偏差分析与处理

Deviation Analysis and Treatment of Liquid Level Measurement of Steam Generator in a Nuclear Power Plant

某核电厂蒸汽发生器液位仪表(MN)分为窄量程和宽量程,共计15块,皆为核级仪表。其中12块窄量程液位测量仪表为机组热态时使用,参与反应堆重要控制保护逻辑。该类型仪表在蒸汽发生器冷态情况下进行换算交叉比对均显示正常。而在机组进行热态功能试验一回路达到热停堆平台时,蒸汽发生器部分窄量程液位仪表多次出现较其他正常液位仪表显示逐渐偏高情况,最大偏差达到30 cm左右,超过维修程序要求。而该类型热态仪表测量偏差过大问题直接制约机组调试工作和机组控制的安全。通过液位测量理论计算与现场检查相结合,分析蒸汽发生器液位仪表测量偏差的根本原因,制定实施方案并通过现场验证。该方案能够保证蒸汽发生器液位仪表测量交叉比对偏差满足维修程序要求,进一步保障核电站的安全稳定运行,同时也为后续此类型仪表的安装和偏差问题的处理积累经验。

A nuclear power plant steam generator level meter(MN)is divided into narrow range and wide range,a total of 15 pieces,all are nuclear level meters.Among them,12 narrow range liquid level measuring instruments are used in the hot state of the unit and participate in the important control and protection logic of the reactor.This type of instrument in the steam generator cold case for conversion cross-reference all showed normal.And hot function test in unit time way to hot shutdown platform when the steam generator part narrow range liquid level meter appears many times than other normal liquid level instrument display gradually on the high side,the largest deviation is about 30 cm,more than maintenance program requirements.The large measurement deviation of this type of thermal instrument directly restricts the safety of unit debugging and unit control.Through the combination of theoretical calculation of liquid level measurement and on-site inspection,the root cause of measurement deviation of liquid level instrument of steam generator was analyzed,and the implementation plan was developed and verified on site.This scheme can ensure that the cross-comparison deviation of the steam generator level instrument can meet the requirements of the maintenance procedure,further guarantee the safe and stable operation of the nuclear power plant,and meanwhile accumulate experience for the subsequent installation of this type of instrument and the treatment of deviation problems.