Sill C W
Idaho National Engineering Laboratory, Lockheed Idaho Technologies Co., Idaho Falls 83415, USA.
Health Phys. 1995 Jul;69(1):21-33. doi: 10.1097/00004032-199507000-00004.
During retrieval and disposition of wastes containing transuranium elements, continuous monitoring of the air, water, and soil for alpha emitters was required to ensure that safety limits were not exceeded and that the waste itself was not disturbed unknowingly. Direct measurements by alpha spectrometry were particularly promising because of their potential speed, sensitivity, and their ability to identify transuranium radionuclides under field conditions. Soil samples or settled dusts were finely ground, suspended in 80% ethanol, sprayed onto circular stainless steel pans, and dried on a hotplate. Water samples were mounted directly by spraying. Air dusts were collected with a high-volume air sampler on 20- by 25-cm membrane filters. The samples were then analyzed directly in a large pressurized gridded ionization chamber without further sample preparation. The lower limits of detection for 10-min counting times were 1.5 Bq g-1 (40 pCi g-1) for 100-mg soil samples, and 4 x 10(-2) Bq m-3 (10(-12) microCi mL-1) for a 10-min air sample taken at 0.4 m3 min-1 (14 cubic feet per minute) and counted without waiting for decay of radon progeny.
在含超铀元素废物的回收与处置过程中，需要对空气、水和土壤中的α发射体进行连续监测，以确保不超过安全限值，且废物本身不会在不知情的情况下受到扰动。α能谱直接测量因其潜在的速度、灵敏度以及在现场条件下识别超铀放射性核素的能力而特别有前景。土壤样品或沉降灰尘被精细研磨，悬浮于80%乙醇中，喷在圆形不锈钢盘上，并在热板上干燥。水样直接通过喷雾进行装样。空气灰尘用大容量空气采样器收集在20×25厘米的膜滤器上。然后，样品无需进一步制备即可直接在大型加压栅格电离室中进行分析。对于100毫克土壤样品，10分钟计数时间的检测下限为1.5贝克勒尔/克（40皮居里/克）；对于以0.4立方米/分钟（14立方英尺/分钟）采集并在不等待氡子体衰变的情况下计数的10分钟空气样品，检测下限为4×10⁻²贝克勒尔/立方米（10⁻¹²微居里/毫升）。
