1.1 本试验方法包括通过氚β粒子活性的液体闪烁计数测定饮用水中的氚。 1.2 该试验方法已成功用于饮用水。用户有责任确保本试验方法对未经测试的水基质的有效性。 1.3 氚浓度的范围为小于0.037 Bq/mL（1 pCi/mL）到555 Bq/mL（15 000 pCi/mL），用于10 mL等分样品。更高的氚浓度可以通过稀释或使用较小的样品小份或两者来测量。 1.4 美国环境保护局（美国EPA）国家初级饮用水法规（NPDWR）规定的饮用水中氚的最大污染水平为0.740 Bq/mL（20 pCi/mL）。NPDWR列出了饮用水中氚的要求检测限为0。 037 Bq/mL（1 pCi/mL），这意味着在需要的情况下，应以0.037 Bq/mL（1 pCi/mL）的灵敏度监测饮用水供应中的氚。在里面 附录X1 , 等式X1.3 用于确定必要的计数时间，以满足饮用水监测所需的灵敏度。 1.5 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.6 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 本试验方法用于测量水中的氚，以确定其浓度是否超过饮用水法规。本试验方法也适用于根据核电设施运行技术规范的要求测定水中氚浓度。通过适当的计数技术、样本量和计数时间，通过液体闪烁可以达到小于37 Bq/L（1000 pCi/L）的检测极限。

1.1 This test method covers the determination of tritium in drinking water by liquid scintillation counting of the tritium beta particle activity. 1.2 This test method is used successfully with drinking water. It is the user’s responsibility to ensure the validity of this test method for untested water matrices. 1.3 The tritium concentrations, which can be measured by this test method utilizing currently available liquid scintillation instruments, range from less than 0.037 Bq/mL (1 pCi/mL) to 555 Bq/mL (15 000 pCi/mL) for a 10-mL sample aliquot. Higher tritium concentrations can be measured by diluting or using smaller sample aliquots, or both. 1.4 The maximum contaminant level for tritium in drinking water as given by the United States Environmental Protection Agency (U.S. EPA) National Primary Drinking Water Regulations (NPDWR) is 0.740 Bq/mL (20 pCi/mL). The NPDWR lists a required detection limit for tritium in drinking water of 0.037 Bq/mL (1 pCi/mL), meaning that drinking water supplies, where required, should be monitored for tritium at a sensitivity of 0.037 Bq/mL (1 pCi/mL). In Appendix X1 , Eq X1.3 is given for determining the necessary counting time to meet the required sensitivity for drinking water monitoring. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 This test method was developed for measuring tritium in water to determine if the concentration exceeds the regulatory statutes of drinking water. This test method also is applicable for the determination of tritium concentration in water as required by technical specifications governing the operations of nuclear power facilities. With suitable counting technique, sample size, and counting time a detection limit of less than 37 Bq/L (1000 pCi/L) is attainable by liquid scintillation.