Non destructive localization by gamma tomography of fission products emission in a fuel pencil area after an accidental sequence

摘要

The transverse gamma spectrometry of an irradiated fuel pencil, associated to a tomography method of gamma emitters reconstruction in a straight section of the pencil, is a non destructive technique which proves efficient when there are enough projections. For a little irradiated fuel, four to six projections equally distributed on 180 degrees and associated to an activity repartition initial model with symmetry of revolution are generally sufficient. For a very damaged fuel, it is necessary to practice eighteen projections every ten degrees; the initial repartition model is no more a noticeable parameter. Applied to the VERCORS safety programme, it allows to know the fuel behavior in situation of serious accident and the radial migrations of fission products. The localization of gamma emitters fission products brings informations supplementary to others optical techniques (ceramographies), or chemical techniques (micro-probe). Then, by its non destructive aspect, it can be in certain cases, unavoidable in front of usual destructive techniques. (N.C.). 4 refs.