Fractionation of radionuclides in liquid samples from nuclear power facilities

Even in acidified liquid samples from nuclear power facilities fractionation of radionuclides among the solution, filterable material and container walls is the rule rather than the exception. The nuclides sorbed onto the walls of plastic containers cannot be removed easily by washing with strong mineral acids but can be wiped from the walls of the containers. Data showing the variable and severe degree of radionuclide fractionation are presented. Paper pulp added to acidified samples at the time of collection concentrates the nuclides and minimizes their sorption onto container walls. Filtration, wet ashing of the filterable material, washing of the container and reconstitution of the fractions provides a stable, homogeneous solution from which reliable analyses can be obtained. With few exceptions, recoveries are greater than 95% for each nuclide in the sample. (author)