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

摘要

Direct measurement of the plutonium content in spent nuclear fuel is achallenging problem in non-destructive assay. The very high gamma-rayflux from fission product isotopes overwhelms the weaker gamma-ray emissionsfrom plutonium and uranium, making passive gamma-ray measurementsimpossible. However, the intense fission product radiation is effectiveat exciting plutonium and uranium atoms, resulting in subsequent fluorescenceX-ray emission. K-shell X-rays in the 100 keV energy range canescape the fuel and cladding, providing a direct signal from uranium andplutonium that can be measured with a standard germanium detector. Themeasured plutonium to uranium elemental ratio can be used to compute theplutonium content of the fuel. The technique can potentially provide a passive,non-destructive assay tool for determining plutonium content in spentfuel. In this paper, we discuss recent non-destructive measurements of plutoniumX-ray fluorescence (XRF) signatures from pressurized water reactorspent fuel rods. We also discuss how emerging new technologies, like veryhighenergy resolution microcalorimeter detectors, might be applied to XRFmeasurements.