Salonen Laina
STUK - Radiation and Nuclear Safety Authority, P.O. Box 14, FIN-00881 Helsinki, Finland.
Appl Radiat Isot. 2010 Oct;68(10):1970-9. doi: 10.1016/j.apradiso.2010.03.003. Epub 2010 Mar 6.
Direct liquid scintillation (LS) methods are widely used for surveying (222)Rn in drinking water. Two direct methods are used that differ in sample composition. In a two-phase sample, water lies below a water-immiscible cocktail, while in a homogeneous sample water is mixed with an emulsifying cocktail. Although these methods were developed in the late 1970s, their performances have not been simultaneously tested. Here, the methods were compared in two ways: by preparing both types of sample similarly from (222)Rn-bearing groundwater in one emulsifying and in three organic cocktails, and by calibrating the methods with a (226)Ra standard according to their respective procedures. The samples were measured using alpha/beta LS spectrometry. The standard deviations of parallel samples and the repeatability of the measurements were excellent for both methods, except two-phase (226)Ra samples, whose efficiencies decreased slightly over time. This instability was due to interference from (210)Pb, (210)Bi and (210)Po, which accumulated in the (226)Ra standard, and possibly also to the migration of (214)Pb and (214)Bi into the aqueous phase and deficient transfer of (222)Rn from the water to the cocktail.
直接液体闪烁（LS）法被广泛用于检测饮用水中的（222）Rn。使用了两种直接方法，它们在样品组成上有所不同。在两相样品中，水位于与水不混溶的闪烁液下方，而在均匀样品中，水与乳化闪烁液混合。尽管这些方法是在20世纪70年代末开发的，但它们的性能尚未同时进行测试。在这里，通过以下两种方式对这些方法进行了比较：以一种乳化剂和三种有机闪烁液从含（222）Rn的地下水中类似地制备两种类型的样品，并根据各自的程序用（226）Ra标准对方法进行校准。使用α/β液体闪烁光谱法对样品进行测量。除了两相（226）Ra样品外，两种方法的平行样品标准偏差和测量重复性都非常好，两相（226）Ra样品的效率随时间略有下降。这种不稳定性是由于（210）Pb、（210）Bi和（210）Po的干扰，它们在（226）Ra标准中积累，也可能是由于（214）Pb和（214）Bi迁移到水相中以及（222）Rn从水到闪烁液中的转移不足。
