The ongoing decommissioning of the Fukushima Daiichi (1F) nuclear power plant requires the inspection of the inside of containment vessels that have been submerged in water. These inspections must locate leaks and map...The ongoing decommissioning of the Fukushima Daiichi (1F) nuclear power plant requires the inspection of the inside of containment vessels that have been submerged in water. These inspections must locate leaks and map the distribution of fuel debris in water with very low visibility. This paper reports the design and testing of an echo-PIV system that uses a single divergent signal wave and delay-and-sum processing to efficiently map the interior and fluid flow within a submerged vessel. The diverging wave and delay-and-sum processing improve upon the performance of conventional ultrasound PIV methods specifically to meet the demands of containment vessel inspections. The imaging method uses an ultrasonic linear sensor array that emits a diverging wave that covers a wide angle with a single transmission. The delay-and-sum algorithm combines echo signals recorded by each element of the sensor array. We optimized the design of an echo-PIV system in laboratory-scale tests, and then tested the prototype with a mockup of a containment vessel in a water tank. The small-scale prototype successfully located a mock leak and mapped the surface of a piece of mock debris. This prototype can be scaled up readily for inspections at the Fukushima Daiichi plant.展开更多
选用FY-4A卫星闪电成像仪(Lightning Mapping Imager, LMI)数据、闪电定位数据(Advanced Time of Arrival and Direction, ADTD)、常规探空资料、区域自动站资料、多普勒天气雷达与ERA5再分析资料,对2023年7月河北省一次特大暴雨过程的...选用FY-4A卫星闪电成像仪(Lightning Mapping Imager, LMI)数据、闪电定位数据(Advanced Time of Arrival and Direction, ADTD)、常规探空资料、区域自动站资料、多普勒天气雷达与ERA5再分析资料,对2023年7月河北省一次特大暴雨过程的闪电变化特征进行对比分析。结果表明:两种闪电资料的时空分布存在差异,LMI的闪电白天少、夜间多,数量约为ADTD的1/8。降雨分布与闪电密度分布也存在差异,ADTD探测的地闪密度高值区位于河北中东部,累计降水量超过400 mm的区域位于河北西部,强降水分布与35 dBZ以上回波的频次分布相一致。降水强度与闪电频次相关关系不显著,7月29—30日强降水过程的闪电活动不活跃,7月31日至8月1日随回波顶位置升高、冰相层增厚,强降水过程的闪电活动显著增强,闪电分布与45 dBZ以上强回波垂直结构及粒子分布均较为密切。展开更多
文摘The ongoing decommissioning of the Fukushima Daiichi (1F) nuclear power plant requires the inspection of the inside of containment vessels that have been submerged in water. These inspections must locate leaks and map the distribution of fuel debris in water with very low visibility. This paper reports the design and testing of an echo-PIV system that uses a single divergent signal wave and delay-and-sum processing to efficiently map the interior and fluid flow within a submerged vessel. The diverging wave and delay-and-sum processing improve upon the performance of conventional ultrasound PIV methods specifically to meet the demands of containment vessel inspections. The imaging method uses an ultrasonic linear sensor array that emits a diverging wave that covers a wide angle with a single transmission. The delay-and-sum algorithm combines echo signals recorded by each element of the sensor array. We optimized the design of an echo-PIV system in laboratory-scale tests, and then tested the prototype with a mockup of a containment vessel in a water tank. The small-scale prototype successfully located a mock leak and mapped the surface of a piece of mock debris. This prototype can be scaled up readily for inspections at the Fukushima Daiichi plant.
文摘选用FY-4A卫星闪电成像仪(Lightning Mapping Imager, LMI)数据、闪电定位数据(Advanced Time of Arrival and Direction, ADTD)、常规探空资料、区域自动站资料、多普勒天气雷达与ERA5再分析资料,对2023年7月河北省一次特大暴雨过程的闪电变化特征进行对比分析。结果表明:两种闪电资料的时空分布存在差异,LMI的闪电白天少、夜间多,数量约为ADTD的1/8。降雨分布与闪电密度分布也存在差异,ADTD探测的地闪密度高值区位于河北中东部,累计降水量超过400 mm的区域位于河北西部,强降水分布与35 dBZ以上回波的频次分布相一致。降水强度与闪电频次相关关系不显著,7月29—30日强降水过程的闪电活动不活跃,7月31日至8月1日随回波顶位置升高、冰相层增厚,强降水过程的闪电活动显著增强,闪电分布与45 dBZ以上强回波垂直结构及粒子分布均较为密切。
