Nondestructive Determination of Relative Plutonium Content in MOX Fuel Pins for Pressurized Heavy Water Reactors Using Passive Gamma Scanning

Abstract

Passive gamma scanning (PGS) for detecting the variations in relative PuO2 content (composition) in (U,Pu) mixed oxide (MOX) fuel pins with low PuO2 content (0.4%) for pressurized heavy water reactors is demonstrated. Experiments are carried out with MOX pins of varying compositions with a NaI(Tl) detector. An annular detector was used to improve the counting statistics, and it was demonstrated that a change of PuO2 content of ±0.02% could be detected at a very low level of PuO2 content of 0.4%. It was also observed that a larger-sized PuO2 agglomerate of 1 mm located near the surface of the pellets could be detected during PGS of the welded fuel pins.