Characterization of whole assembly hulls produced by industrial reprocessing of LWR fuels

The characterization program for Obrigheim and Stade PWR hulls sampled at La Hague was conducted in the CEA hot cells (Coquenstock program operating on whole assembly hulls). A description of the appearance of these hulls, recovered on the industrial scale and after severe damage, is followed by a review of the results of the different radiochemical characterization operations (neutron emission measurements, gamma scanning, alpha and mass spectrometry after dissolution of several samples, determination of the retention of tritium and other gaseous fission products occluded in the zircalloy clads etc). The alpha contamination of these hulls proved to be rather high, but it demonstrated that a large part (90 to 95%) was labile and could be removed by simple rinsing with cold 3N nitric acid. By contrast, contamination by fission products such as Cs 137, Ce 144 and Eu 154, remains high and relatively unaffected by nitriacid rinsing. Based on the results obtained and the observations recorded, an analysis is carried out of the origins of alpha contamination of these hulls treated on an industrial scale, among which the chief source is certainly the limited effectiveness of rinsing