本文件规定了一种水样物理预处理和调节方法，以及测定发射能量在40？Keve？然后呢？2？MeV，通过伽马？根据ISO中描述的通用测试方法进行射线光谱测定？20042. 该方法适用于饮用水、雨水、地表水和地下水以及冷却水、工业用水、生活和工业废水的测试样品，经过适当的取样、样品处理和测试样品制备（必要时过滤并考虑水中溶解物质的量）。本方法仅适用于均质样品或及时过滤均质的样品。 无需浓缩样品或仅使用检测系统的被动屏蔽即可测得的最低限约为5·10-2？对于例如137Cs.1，活性的上限对应于10%的死区时间。可以使用更高的死区时间，但是需要死区时间校正的准确性的证据。 取决于不同的因素，如伽马射线的能量、每次核衰变的发射概率、样品和探测器的尺寸和几何形状、屏蔽、计数时间和其他实验参数，如果活度低于5·10-2，则可能需要通过蒸发浓缩样品？需要测量Bq/l。然而，挥发性放射性核素（例如氡和放射性碘）可能在源制备过程中损失。 这种方法适合在紧急情况下应用。 ？ 1样品几何形状:3l Marinelli烧杯；检测器:GE HP N相对效率55%；计数时间:18小时。

This document specifies a method for the physical pre-treatment and conditioning of water samples and the determination of the activity concentration of various radionuclides emitting gamma-rays with energies between 40？keV？and？2？MeV, by gamma？ray spectrometry according to the generic test method described in ISO？20042. The method is applicable to test samples of drinking water, rainwater, surface and ground water as well as cooling water, industrial water, domestic and industrial wastewater after proper sampling, sample handling, and test sample preparation (filtration when necessary and taking into account the amount of dissolved material in the water). This method is only applicable to homogeneous samples or samples which are homogeneous via timely filtration. The lowest limit that can be measured without concentration of the sample or by using only passive shield of the detection system is about 5·10^-2？Bq/l for e.g. ¹³⁷Cs.¹ The upper limit of the activity corresponds to a dead time of 10 %. Higher dead times may be used but evidence of the accuracy of the dead-time correction is required. Depending on different factors, such as the energy of the gamma-rays, the emission probability per nuclear disintegration, the size and geometry of the sample and the detector, the shielding, the counting time and other experimental parameters, the sample may require to be concentrated by evaporation if activities below 5·10^-2？Bq/l need to be measured. However, volatile radionuclides (e.g. radon and radioiodine) can be lost during the source preparation. This method is suitable for application in emergency situations. ？ ¹The sample geometry: 3l Marinelli beaker;detector: GE HP N relative efficiency 55 %;counting time: 18h.