Rodgers J C, Fairchild C I, Wood G O, Ortiz C A, Muyshondt A, McFarland A R
Los Alamos National Laboratory, NM 87544, USA.
Health Phys. 1996 Jan;70(1):25-35. doi: 10.1097/00004032-199601000-00005.
Alternative reference methodologies have been developed for sampling of radionuclides from stacks and ducts, which differ from the methods previously required by the United States Environmental Protection Agency. These alternative reference methodologies have recently been approved by the U.S. EPA for use in lieu of the current standard techniques. The standard EPA methods are prescriptive in selection of sampling locations and in design of sampling probes whereas the alternative reference methodologies are performance driven. Tests were conducted in a stack at Los Alamos National Laboratory to demonstrate the efficacy of some aspects of the alternative reference methodologies. Coefficients of variation of velocity, tracer gas, and aerosol particle profiles were determined at three sampling locations. Results showed that numerical criteria placed upon the coefficients of variation by the alternative reference methodologies were met at sampling stations located 9 and 14 stack diameters from the flow entrance, but not at a location that was 1.5 diameters downstream from the inlet. Experiments were conducted to characterize the transmission of 10 microns aerodynamic diameter liquid aerosol particles through three types of sampling probes. The transmission ratio (ratio of aerosol concentration at the probe exit plane to the concentration in the free stream) was 107% for a 113 L min-1 (4-cfm) anisokinetic shrouded probe, but only 20% for an isokinetic probe that follows the existing EPA standard requirements. A specially designed isokinetic probe showed a transmission ratio of 63%. The shrouded probe performance would conform to the alternative reference methodologies criteria; however, the isokinetic probes would not.
已开发出用于从烟囱和管道中采集放射性核素的替代参考方法，这些方法与美国环境保护局先前要求的方法不同。这些替代参考方法最近已获美国环保署批准，可用于替代当前的标准技术。美国环保署的标准方法在采样位置的选择和采样探头的设计方面具有规定性，而替代参考方法则以性能为导向。在洛斯阿拉莫斯国家实验室的一个烟囱中进行了测试，以证明替代参考方法某些方面的有效性。在三个采样位置测定了速度、示踪气体和气溶胶颗粒剖面的变异系数。结果表明，在距离气流入口9个和14个烟囱直径的采样站满足了替代参考方法对变异系数设定的数值标准，但在入口下游1.5个直径处的位置未满足。进行了实验，以表征10微米空气动力学直径的液体气溶胶颗粒通过三种类型采样探头的传输情况。对于一个113升/分钟（4立方英尺/分钟）的非等速带罩探头，传输比（探头出口平面处的气溶胶浓度与自由流中浓度的比值）为107%，但对于符合现有美国环保署标准要求的等速探头，传输比仅为20%。一个专门设计的等速探头显示传输比为63%。带罩探头的性能符合替代参考方法的标准；然而，等速探头则不符合。
