The probabilistic approach was applied for the interpretation of results from the assay of solid nuclear waste by one-shot passive gamma technique. Under the assumption of random loading into the waste container, any distribution of source and material in the container volume can be expected. In the study an approach based on systematic scan of the possible distributions is described. The occurrence probabilities for all these distributions are combined and yield the probability distribution of the source mass in the waste container. Thus, the problematics of the uncertainty due to nonhomogeneity of the waste are overcome. The presentation starts with a line item and then advances to spherical and cylindrical. The resulting mass distributions for a number of containers are demonstrated. It is shown that the addition of information narrows the mass distribution.