Huang Suilou, Schery Stephen D, Alcantara Raul E, Rodgers John C, Wasiolek Piotr T
Atmospheric Radioactivity Group, Geophysical Research Center, New Mexico Institute of Mining and Technology, Socorro 87801, USA.
Health Phys. 2002 Dec;83(6):884-91. doi: 10.1097/00004032-200212000-00016.
Alpha-particle continuous air monitors must sometimes be operated in dusty environments where significant dust loading of the filter can be anticipated. It is important to understand how this dust loading affects the response of the continuous air monitors. Not only must a filter be changed if there is a reduction in airflow, but a change may be necessary if the energy resolution deteriorates and the continuous air monitor loses sensitivity and specificity for the radioactive aerosols of interest. A series of experiments were conducted to investigate alpha-particle energy resolution of continuous air monitor filters, particularly under dust loading conditions. Aerosol particles of various sizes were tagged with radon decay products to serve as surrogates for radioactive aerosols of interest such as plutonium or uranium. While the size of radioactive aerosols, filter type, and dust type affected the energy resolution, the thickness of an underlying (nonradioactive) dust layer did not show significant effect for the materials studied and a loading range of 0.01-10 mg x cm(-2). Our results indicate that it is possible for continuous air monitors to detect the release of radioactive aerosols with little deterioration in energy resolution under conditions of significant dust loading provided that the deposited layer of radioactive aerosols remains thin (< or = 0.1 mg x cm(-2)).
α粒子连续空气监测仪有时必须在多尘环境中运行，在这种环境下，预计过滤器会有大量灰尘附着。了解这种灰尘附着如何影响连续空气监测仪的响应非常重要。如果气流减少，不仅必须更换过滤器，而且如果能量分辨率变差，连续空气监测仪对感兴趣的放射性气溶胶失去灵敏度和特异性，也可能需要更换。进行了一系列实验来研究连续空气监测仪过滤器的α粒子能量分辨率，特别是在灰尘附着条件下。用氡衰变产物标记各种尺寸的气溶胶颗粒，以替代感兴趣的放射性气溶胶，如钚或铀。虽然放射性气溶胶的尺寸、过滤器类型和灰尘类型会影响能量分辨率，但在所研究的材料和0.01 - 10 mg x cm(-2)的负载范围内，下层（非放射性）灰尘层的厚度未显示出显著影响。我们的结果表明，在大量灰尘附着的条件下，只要放射性气溶胶的沉积层保持薄（≤0.1 mg x cm(-2)），连续空气监测仪就有可能在能量分辨率几乎没有恶化的情况下检测到放射性气溶胶的释放。
