137Cs pre-concentration from water samples using Prussian blue impregnated ion-exchanger

During the intermediate and the late phase of a nuclear accident, the water derived intervention levels can vary widely, depending on site-specific factors, integration time and intervention levels. If one considers 1% of the derived intervention level as the desired detection limit, large counting times or large sample volumes may be necessary. In order to reduce both counting time and sample volume to be handled, sample concentration methods can be useful. For 137Cs the use of hexa cyanoferrate compounds for this purpose is not new. The hexacyanoferrate compound can be used as it self or impregnated on ion-exchangers or silica-gel. The associated cation can be iron (III), nickel, cobalt or zinc. Using for seawater sampling purpose cupric hexacyanoferrate impregnated on an ion-exchanger, it was possible to sample up to thousand liters with a flow rate of 3 liter/min. During the Goiania accident iron (III) hexacyanoferrate impregnated ion-exchanger columns were used in the hospitals to avoid the discharge of contaminated urine, since the urine of the patients had 137Cs content up to 37 MBq/L. These columns (5 cm diameter and 50 cm height) could handle up to 100 liters urine with complete 137Cs retention. Based on this experience we decided to use the same impregnated resin in the analysis of 137Cs river waters at Goiania. This work describes the experiments related to the adaptation of the method for this specific purpose