Rapid measurement of radiocesium in water using a Prussian blue impregnated nonwoven fabric

We developed a rapid method for concentrating and measuring radiocesium (¹³⁴Cs and ¹³⁷Cs) dissolved in fresh water using nonwoven fabric impregnated with Prussian blue (PB) as a radiocesium absorber in combination with gamma-ray spectrometry using a germanium (Ge) detector. Utilizing this method, dissolved radiocesium in a 20–100 L freshwater sample could be concentrated within a period of 20–60 min by passing the sample through 10–12 columns, connected in series, that had been fitted with nonwoven fabric disks impregnated with PB. Laboratory tests using water samples containing known amounts of radiocesium confirmed that the overall recovery rate of the isotope was 100%–108%, and that the first six columns recovered 84%–97% of the isotope. The detection limit of this method was determined to be 0.002 Bq/L with a sample of 100 L and measurement time of 43,200 s. In comparison with traditional methods using ion-exchange resin, co-precipitation with ammonium phosphomolybdate, etc., our method has the advantages of reduced cost and a significantly shorter concentration time. Since water samples can be treated in short periods of time, it is now possible to conduct radiocesium pre-concentration in situ, thus eliminating the need to transport large-volume water samples to laboratories.