【国外标准】 Standard Test Method for Uranium in Drinking Water by High-Resolution Alpha-Liquid-Scintillation Spectrometry (Withdrawn 2024)

5.1 This test method is a fast, cost-effective method that can yield limited isotopic activity levels for 238U and 234U, as well as total uranium activity. Although 232U is incorporated as a tracer, uranium recoveries for this test measured during the developmental work on this test method were usually between 95 and 105%. 5.2 The high-resolution alpha-liquid-scintillation spectrometer offers a constant (99.6 ± 0.1) % counting efficiency and instrument backgrounds as low as 0.001 counts per minute (min–1 ) over a 4 to 7 MeV energy range according to McDowell and McDowell (2). Count rates for extractive scintillator blanks and reagent blanks usually range from 0.01 min–1 to 0.1 min–1. 1.1 This test method covers determining the total soluble uranium activity in drinking water in the range of 0.037 Bq/L (1 pCi/L) or greater by selective solvent extraction and high-resolution alpha-liquid-scintillation spectrometry. The energy resolution obtainable with this technique also allows estimation of the 238U to 234U activity ratio. 1.2 This test method was tested successfully with reagent water and drinking water. It is the user's responsibility to ensure the validity of this test method for waters of untested matrices. 1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 9.