Development of hybrid feed water flow rate measurement system for light water reactors of nuclear power plants using pulse Ultrasound

针对核电站轻水堆给水流量测量系统的新型结构，研制了一种脉冲超声波给水流量测量系统。该系统综合了飞行时间（TOF）型超声波流量计和速度剖面型超声波流量计的优点，是一种新型的流量计。我们的最终目的是将混合式超声波流量测量系统应用于核电站给水流量的精确测量。称为UDM流量计的超声波速度分布型流量计基于脉冲超声波多普勒方法（UDM），其具有获得沿超声波束沿着的瞬时速度分布的能力。UDM流量计量系统的原理是基于对管道直径上的瞬时速度分布的积分。多光束系统有望消除安装问题，如入口长度，并通过增加流量精确跟踪瞬时流量。 ...更多信息 从而改变超声换能器的数量。然而，它需要反射器来接收超声多普勒信号。另一方面，TOF超声波流量测量系统不需要任何反射器，但它需要依赖于速度剖面的剖面因子（PF）。PF是准确测量流量的重要实验系数之一。因此，必须根据流动条件的变化来校正PF。在本研究中，我们研究了混合超声波流量测量系统可以在多大程度上通过使用UDM来校正TOF超声波流量计的剖面因子。结果，实验室实验表明，对于充分发展的流动条件，仅使用单个测量线就可以实现准确的流量测量，此外，对于弯曲管道正下方的非发展流，多线法得到了成功的应用，误差小于1%。利用超声空化泡可以有效地获得超声反射器。即使对于金属壁管道，与使用尼龙粉末相比，空化气泡似乎也可用于测量瞬时速度分布和流量。如前所述，表明目前采用超声多普勒方法的多管路流量计量系统在非理想流动条件下，如非发展流动或非轴对称流动，具有很高的精度。利用金属管道和空化气泡作为超声波反射体，构建了电厂流量测量的基本系统。根据本实验的结果，PF值的偏差最大可达2-6%，直接影响流量的估计。然而，通过使用UDM测量进行校准，PF可以更好地在± 1%以内。少

A new feed water flow rate measurement system for light water reactors of nuclear power plants using pulse Ultrasound has been developed for a new type of flow metering system. This new system is a hybrid of the time-of-flight (TOF) type ultrasonic flowmeter and the ultrasonic velocity profile type flowmeter with the advantages of these two types. Our final purpose is to apply the hybrid ultrasonic flow metering system to an accurate flow rate measurement of feed- water in nuclear power plants. The ultrasonic velocity profile type flowmeter called the UDM flowmeter is based on the pulse ultrasonic Doppler method (UDM) which has the capability to obtain instantaneous velocity profiles along an ultrasonic beam. The principle of the UDM flow metering system is based on the integration of an instantaneous velocity profile over a pipe diameter. The multi-beam system is expected to eliminate installation problems such as entry length, and also to follow transient flow rate precisely by incre … More asing the number of ultrasonic transducers. However, it needs reflectors for receiving ultrasonic Doppler signals. On the other hand, the TOF ultrasonic flow metering system does not need any reflector, but it needs profile factors (PFs) which depend on velocity profiles. PF is one of the important experimental coefficients for the accurate flow rate measurement. Therefore PFs must be corrected according to the changes in flow conditions. In the present study, we investigated to what degree the hybrid ultrasonic flow metering system can correct the profile factors of TOF ultrasonic flow meters by using the UDM.As results, the laboratory experiments appeared that for fully developed flow condition an accurate measurement of flow rate was achievable using only a single measuring line, and additionally, for non developed flow which is located just below the bend pipe the multi-lines method was successfully applied and the errors were less than 1%. The reflector of ultrasound was obtained very efficiently using ultrasonic cavitation bubbles. Even for the metallic wall pipe, it was appeared that cavitation bubbles were available to measure the instantaneous velocity profile and the flow rate accurately compared with using nylon powder. As mentioned above, it is indicated that the present multi-lines flow metering system by using ultrasonic Doppler method has very high accuracy under non-ideal flow conditions such as non-developed flow or non-axis-symmetric flow. And we constructed the basic system of a flow rate measurement in power plants using metallic pipes and cavitation bubbles as ultrasound reflectors. And according to the results of this experiment, deviation of PFs could be around 2-6% at maximum, which directly affects the estimation of flow rates. However by calibration with UDM measurement PFs could be better within ±1%. Less