Significance and Use
5.1 Radium is one of the most radiotoxic elements. Its isotope of mass 226 is the most hazardous because of its long half-life. The isotopes 223 and 224, although not as hazardous, are of some concern in appraising the quality of water.
5.2 The alpha-particle-emitting isotopes of radium other than that of mass 226 may be determined by difference if radium-226 is measured separately, such as by Test Method D3454. Note that one finds 226Ra and 223Ra together in variable proportions (5, 6), but 224Ra does not normally occur with them. Thus, 223Ra often may be determined by simply subtracting the 226Ra content from the total: and if 226Ra and 223Ra are low, 224Ra may be determined directly. The determination of a single isotope in a mixture is less precise than if it occurred alone.
1.1 This test method covers the separation of dissolved radium from water for the purpose of measuring its radioactivity. Although all radium isotopes are separated, the test method is limited to alpha-particle-emitting isotopes by choice of radiation detector. The most important of these radioisotopes are 223Ra, 224Ra, and 226Ra. The lower limit of concentration to which this test method is applicable is 3.7 × 10-2 Bq/L (1 pCi/L).
1.2 This test method may be used for absolute measurements by calibrating with a suitable alpha-emitting radioisotope such as 226 Ra, or for relative methods by comparing measurements with each other. Mixtures of radium isotopes may be reported as equivalent 226Ra. Information is also provided from which the relative contributions of radium isotopes may be calculated.
1.3 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 a specific precautionary statement, see Section 9.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
C859 Terminology Relating to Nuclear Materials
D1129 Terminology Relating to Water
D1193 Specification for Reagent Water
D1943 Test Method for Alpha Particle Radioactivity of Water
D2777 Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
D3370 Practices for Sampling Water from Closed Conduits
D3454 Test Method for Radium-226 in Water
D3648 Practices for the Measurement of Radioactivity
D4448 Guide for Sampling Ground-Water Monitoring Wells
D5847 Practice for Writing Quality Control Specifications for Standard Test Methods for Water Analysis
D6001 Guide for Direct-Push Groundwater Sampling for Environmental Site Characterization
alpha particles; radioactivity; radium isotopes; water;
ICS Number Code 13.060.50 (Examination of water for chemical substances); 13.060.60 (Examination of water for physical properties)
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Citing ASTM Standards
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