Nuclear Techniques in Nondestructive Testing

Gamma spectroscopy, alpha counting and x-ray fluorescence techniques have been developed and applied to testing nuclear reactor fuel elemsents. A gamma analyzer system incorporating a NaI(Tl) scintillator measures in a two minute counting period the enrichment level of the U-235 isotope over a 0.15 to 3.0 weight percent range with accuracy of about 0.1 percent. An alpha scintillation system, with unusually sturdy mechanical features to position heavy reactor fuel elements,detects uranium contamination at the 100 microgram level in a 10 minute counting period. A prototype x-ray fluorescence system detected uranium contamination in a weld zone over a 2-10 weight percent range in a small volume (0.25×10-3in3) at a scan rate of 5 in/min. These techniques and in particular x-ray fluorescence offer promising methods for testing impurity levels or alloying concentrations of space age components or materials.