Within the framework of nondestructive inspection of irradiation rigs carried out in the pool of the 35-MW Siloe reactor in Grenoble, transverse gamma scanning has been developed. It permits radial distribution of the fission products in irradiated fuels to be determined and, therefore, considerable improvement to be made in the knowledge of their behavior. A new method of transverse measurement treatment has recently been elaborated: the ISARD program reconstructs the distribution of gamma emitters in a section of the fuel pin from several scans carried out under different incidences. The algorithm is built on a combination of two iterative methods and allows a limited number of projections to be used without assuming any particular symmetry, taking the selfattenuation of gamma rays in the fuel element and their absorption by the rig walls into account. The ISARD program has been qualified experimentally, using a sample composed of various materials activated in the reactor. The sample and the irradiation were designed to simulate a large number of different distributions of gamma emitters (i.e., activation products), similar to typical repartitions of fission products in a fuel pin (peripheral or central concentrations, local accumulation or voids . . . ). This qualifying study, treated parametrically, allowed practical choices to be made as to the routine application of the method to irradiated fuel pins.