Plutonium in 50-100g sediments by alpha counting

Sediment

Pu

This method specifies the minimum requirements and laboratory methods for measuring ²³⁸Pu and ^239,240Pu in sediment samples via alpha-counting.

Before digestion, the sample should be ashed at 480 ℃ for 48 h in order to remove the organic matter. This method will meet difficulties when the counting statistics are low or when the alpha spectrum is disturbed by natural radioactivities in the sample or background (Hakanen et al., 1984). It is thus necessary to collect the enough sample volume (about 100 g) due to low ²³⁸Pu activity. Interference is especially due to ²²⁸Th, indicated by the presence of ²²⁴Ra in the alpha spectrum. Meanwhile, this method cannot separate ²³⁹Pu and ²⁴⁰Pu because of their similar energy.