ISO/CD 18990

Résumé

This proposed standard is applicable the analysis of plutonium (238Pu, 239Pu and 240Pu) in urine, which can be used for the internal dose monitoring of the public, occupational and rescue under accident conditions. The range of radioactivity are 1×10-4 Bq/L to 0.1 Bq/L for 238Pu and 1×10-5 Bq/L to 1×10-2 Bq/L for 239Pu and 240Pu. This standard introduces methods for the determination of plutonium (238Pu, 239Pu and 240Pu) in urine using alpha spectrometry and inductively coupled plasma mass spectrometry (ICP-MS). 238Pu is measured by the alpha spectrometry method due to the relatively short half-life (87.74 year) and the isobaric interference (238U) with the mass spectrometry measurement of 238Pu. Because the energy of α-particle of 239Pu and 240Pu are 5155 keV and 5168 keV, respectively, the α-spectrum peaks are seriously overlapped. Therefore, the α-spectrum method is only suitable for analyzing the activity of 239+240Pu. The ICP-MS is selected If the 239Pu and 240Pu need to be measurement 239Pu and 240Pu respectively. The measurement method can be selected according to the experimental conditions, sample size and analysis time requirements. The urine samples need to be acidified before preserved, and pretreated before measurement. The detection limit depends on the chemical separation and the performance of measuring instrument.