Year
2012
Abstract
Facilities that produce or handle mixed uranium-plutonium oxide (U-Pu MOX) have the need to measure the U and Pu content of MOX materials. Nearly all commercially-sold Hybrid K-Edge/ x-ray fluorescence Densitometer (HKED) instruments can rapidly measure dissolved MOX materials, provided that suitable HKED software is used for analysis. However, there has been little discussion or consensus among HKED manufacturers about how measurements of U-Pu MOX samples should be calibrated. In this paper, the long-established “Dual-Edge” K-Edge Densitometer (KED) fitting technique is summarized for the reader. The Dual-Edge KED fitting method is well-suited for samples (such as MOX with a U:Pu ratio near unity) that exhibit prominent absorption edges from two actinides. Common mistakes that affect Dual-Edge KED calibration are described, and potential consequences of those errors are explained. Recommended methods for Dual-Edge KED calibration with a single MOX standard, and with multiple MOX standards, are proposed in detail. Suggestions are provided for choosing the U and Pu content of standards to maximize the effectiveness of the calibration. Although measurement scenarios involving U-Pu MOX are the main focus of this paper, the calibration methods could be applied to Dual-Edge KED analysis of any two actinides. Recent efforts to automate the Dual-Edge KED calibration process within the Los Alamos National Laboratory HKED analytical software are also summarized.