分布式光纤测温系统在核电厂的应用实践

Applications of distributed optical fiber temperature sensor system in nuclear power plants

火灾自动报警系统是核电厂消防的必要组成部分,核电厂的特殊性使得该系统的可靠性和稳定性尤为重要。传统温度传感器以电信号为工作基础,易受到核电厂潮湿、盐雾、强电磁干扰、易燃易爆等环境影响,无法保证长期稳定运行。分布式光纤测温系统是基于光信号传输,具有抗电磁干扰、耐腐蚀、耐潮湿、耐盐碱等显著特点,拉曼散射和光时域反射工作原理可实现长距离、实时、在线监测、分布精确定位等技术特性,可靠性与稳定性已得到验证。经系统解调后的数据可实时显示,还可通过阈值设定进行预警和报警,做到防患于未“燃”。基于田湾核电站地下廊道及变压器区域探测器换型改造项目,简述分布式光纤测温系统技术原理,重点介绍现有实施方案及效果,并探索其他可行应用实践。

Automatic fire alarm system plays a significant role in nuclear power plants. Its reliability and stability are especially underlined in these facilities due to the nuclear-related factor. Traditional fire detectors work through electrical current, the function of which can easily be compromised by the adverse impact of humidity, salt mist,electromagnetic interference, inflammables and explosives in nuclear power plants. In comparison, distributed optical fiber temperature sensor system detects temperature and fire by a length of fiber cable and gets immune to the impact because of its optical characteristics. The combination of Raman scattering and optical time domain reflectometry(OTDR) features in distributed, real-time and precise detection over a long distance. The temperature data will finally be processed and displayed by the terminal unit, where early warning and real fire alarm values can be set for multiple purposes. The article addresses hands-on experiences in application of the system at underground corridors and transformer areas in Tianwan Nuclear Power Plant. It also refers briefly to the system’s working theory and explores further applications in nuclear power plants.