Tritium collection efficiency varies as a function of smear media. The use of porous smear materials leads to an increase in the measured tritium activity as a function of time when the measurement is performed with liquid scintillation counters. Operational inclusion of the efficiency differences and the time dependence of the tritium smear activity is necessary to preclude inadvertently releasing materials or areas. Thomas Jefferson National Laboratory Radiological Control Department identified a contaminated stainless steel containment vessel that previously housed a target containing more than 37 TBq of tritium. The item was systematically sectioned and surveyed to compare three smear types: water-wetted cotton swabs, water-wetted paper smears, and ethanol-wetted Styrofoam wipes (NUC-Wipes™). The total activity of each section was determined using repeated decontamination. The time dependence of the measured activity was also studied. The measured activity of both paper smears and cotton swabs showed significant time dependence. The cotton swabs also showed significantly reduced collection efficiency. Given the widespread use of both of these media in routine contamination surveys, site operational limits were derived using fitted curves for time dependence and average efficiency results. The use of these more restrictive limits allows for rapid measurement of tritium smears while ensuring regulatory compliance.

中文翻译：

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氚涂片活动的时间表征。

氚收集效率随涂片介质的变化而变化。当使用液体闪烁计数器进行测量时，使用多孔涂片材料会导致测量的氚活性随时间增加。操作包括效率差异和氚涂片活动的时间依赖性是必要的，以防止无意中释放材料或区域。托马斯杰斐逊国家实验室放射控制部门发现了一个受污染的不锈钢容器，该容器以前装有一个含有超过 37 TBq 氚的靶。系统地对该项目进行切片和调查，以比较三种类型的涂片：水湿棉签、水湿纸涂片和乙醇润湿的聚苯乙烯泡沫塑料湿巾 (NUC-Wipes™)。使用重复去污确定每个部分的总活性。还研究了测量活动的时间依赖性。纸片和棉签的测量活性显示出显着的时间依赖性。棉签也显示出显着降低的收集效率。鉴于这两种介质在常规污染调查中的广泛使用，使用时间依赖性和平均效率结果的拟合曲线得出现场操作限制。使用这些更严格的限制允许快速测量氚涂片，同时确保符合法规。棉签也显示出显着降低的收集效率。鉴于这两种介质在常规污染调查中的广泛使用，使用时间依赖性和平均效率结果的拟合曲线得出现场操作限制。使用这些更严格的限制允许快速测量氚涂片，同时确保符合法规。棉签也显示出显着降低的收集效率。鉴于这两种介质在常规污染调查中的广泛使用，使用时间依赖性和平均效率结果的拟合曲线得出现场操作限制。使用这些更严格的限制允许快速测量氚涂片，同时确保符合法规。