水质. 锶90和锶89. 利用液体闪烁计数或比例计数法的试验方法

[中文适用范围]： 本文件规定了使用液体闪烁计数（LSC）或比例计数（PC）测定环境水样品中 90Sr 和 89Sr 活度浓度的条件。 该方法适用于饮用水、雨水、地表水和地下水、海水以及冷却水、工业用水、生活和工业废水经过适当取样和处理以及测试样品制备后的测试样品。 需要对测试样品进行过滤并进行化学分离，以从样品的测试部分中分离和纯化锶。 检测限取决于样品体积、使用的仪器、样品计数时间、背景计数率、检测效率和化学收率。 本文件中描述的方法使用当前可用的 LSC 计数器，对 89Sr 和 90Sr 的检测限分别约为 10 mBq l−1 和 2 mBq l−1 ，低于 WHO 安全饮用水标准（89Sr 为 100 Bq·l−1，90Sr 为 10 Bq·l−1）[3]。 对于 2 l 的样品体积，计数时间为 1000 分钟即可获得这些值。 本文件中描述的方法适用于紧急情况。 当核事故发生放射性尘埃时，89Sr 对放射性锶总量的贡献是不可忽略的。 本文件提供了在 89Sr 存在下测定 90Sr 活度浓度的测试方法。 该方法不包括悬浮物中吸附的 90Sr 和 89Sr 的分析。 用户有责任确保为测试的水样选择的测试方法的有效性。 [外文原描述]： This document specifies conditions for the determination of 90 Sr and 89 Sr activity concentration in samples of environmental water using liquid scintillation counting (LSC) or proportional counting (PC). The method is applicable to test samples of drinking water, rainwater, surface and ground water, marine water, as well as cooling water, industrial water, domestic, and industrial wastewater after proper sampling and handling, and test sample preparation. Filtration of the test sample and a chemical separation are required to separate and purify strontium from a test portion of the sample. The detection limit depends on the sample volume, the instrument used, the sample count time, the background count rate, the detection efficiency and the chemical yield. The method described in this document, using currently available LSC counters, has a detection limit of approximately 10 mBq l −1 and 2 mBq l −1 for 89 Sr and 90 Sr, respectively, which is lower than the WHO criteria for safe consumption of drinking water (100 Bq·l −1 for 89 Sr and 10 Bq·l −1 for 90 Sr) [ 3 ] . These values can be achieved with a counting time of 1 000 min for a sample volume of 2 l. The methods described in this document are applicable in the event of an emergency situation. When fallout occurs following a nuclear accident, the contribution of 89 Sr to the total amount of radioactive strontium is not negligible. This document provides test methods to determine the activity concentration of 90 Sr in presence of 89 Sr. The analysis of 90 Sr and 89 Sr adsorbed to suspended matter is not covered by this method. It is the user’s responsibility to ensure the validity of this test method selected for the water samples tested.