Measurement of Plutonium in Spent Nuclear Fuel by Self-Induced X-ray Fluorescence

Year
2009
Author(s)
S. Tobin - Los Alamos National Laboratory
Daniel C. Strohmeyer - Nuclear Engineering Department
Steven F. Saavedra - Oak Ridge National Laboratory
W. Charlton - Los Alamos National Laboratory
C.R. Rudy - Los Alamos National Laboratory
A.S. Hoover - Los Alamos National Laboratory
A. Stafford - Texas A&M University
Abstract
Direct measurement of the plutonium content in spent nuclear fuel is a challenging problem in non-destructive assay. The very high gamma-ray ?ux from ?ssion product isotopes overwhelms the weaker gamma-ray emis- sions from plutonium and uranium, making passive gamma-ray measure- ments impossible. However, the intense ?ssion product radiation is effective at exciting plutonium and uranium atoms, resulting in subsequent ?uores- cence X-ray emission. K-shell X-rays in the 100 keV energy range can escape the fuel and cladding, providing a direct signal from uranium and plutonium that can be measured with a standard germanium detector. The measured plutonium to uranium elemental ratio can be used to compute the plutonium content of the fuel. The technique can potentially provide a pas- sive, non-destructive assay tool for determining plutonium content in spent fuel. In this paper, we discuss recent non-destructive measurements of plu- tonium X-ray ?uorescence (XRF) signatures from pressurized water reactor spent fuel rods. We also discuss how emerging new technologies, like very- high energy resolution microcalorimeter detectors, might be applied to XRF measurements.