[en] A general sampling specification is used (composition and concentration identity for radionuclides in the sample and effluent) together with current concepts on the states of radionuclides in water to determine the representativness of effluent samples in the determination of radionuclide contents. An additional specification is drawn up for the determination of radionuclide contents: the concentration and composition of the suspensates in the sample transmitted to the averaging volume must be the same as those in the effluent at the time of sampling