Application Research Of Hybrid K-edge/X-ray Fluorescence Densitometry In Purex Process

It is well known that reprocessing plays a vital role in nuclear fuel cycle. The hybrid K-edge/X-ray fluorescence densitometry (HKED), which has been developed as a nondestructive assay method for nuclear Safeguards, is widely applied for special nuclear material accounting measurement in reprocessing plants. It is of big significance for both Safeguards and process control. The development and application of HKED will be described as follows.Improvement of the system and redesign of sample vessel have caused higher measuring efficiency and lower cost. Changing the X-tube and y-source 109Cd and adding stabilizers to both KED and XRF measurement have enhanced the reliability and precision.Further development of analysis software includes improvement of XRF algorithmic code and adding KED code for Pu and Th assay. So the application of HKED method is extended to meet the requirement of Purex process. Also, the potential factors, which may make influence to measuring precision, have been studied.With making a series of standard samples, calibrations have been fulfilled for KED, XRF and HKED, respectively. The analysis using KED method provides a precision of 0.1-0.6% for high concentration 20-350 g/1, and a precision of 0.2-1.0% for low concentration 0.5-20 g/1 can be obtained with XRF. HKED analysis of U/Pu solution such as 1AF in a concentration ratio of 100 yields a precision for U (100-300 g/1) of 0.1-0.2%, and for Pu of 0.7%, respectively.Purex is just one advanced reprocessing process, which is under further developing and has been applied in reprocessing plant in China. As far as Purex process is concerned, a number of samples can be analyzed timely and effectively with the HKED method, and the assay result is of vital importance to accounting of nuclear materials such as U and Pu.