Passive Gamma Scanning which measures the intensity of signature gamma rays coming from plutonium isotopes is one of the NDT techniques used for this purpose. Experimental fuel pins containing pellets of the various enrichment and uranium dioxide pellets were specially fabricated for this purpose. Experimental studies were made to arrive at the optimum parameters. The fuel pins are scanned one by one in a gamma scanner and the data are stored in an IBM-PC. The movement of the fuel pins is computer controlled. The details of gamma scanner system and the results obtained during the inspection of BWR-MOX fuel pins are described.

Gamma autoradiography which records the radiation coming from the fuel pins on industrial X-ray films was also tried in the authors' laboratory. Fuel pins were kept in contact with X-ray films loaded in cassettes and the processed gamma autoradiographs were evaluated.

This paper describes these two nondestructive evaluation techniques in detail and records our experience during the quality control of BWR-MOX fuel elements. The advantages and limitations of these two methods are also brought out in this paper.