Simulation of Nuclear Resonance Fluorescence for the Quantification of Plutonium-239 in Nuclear Fuel

Abstract

There is a need for a technique that is able to quickly and accurately quantify the amount of ^239Pu in spent nuclear fuel. With the recent developments of mono-energetic gamma-ray systems, it may be possible to use Nuclear Resonance Fluorescence for this task. Previous gamma-ray sources for the technique were Bremsstrahlung sources. There was a distinct disadvantage with this technique due to the broad energy spectrum that Bremsstrahlung sources create. However, at Lawrence Livermore National Laboratory a new source has been developed which uses Compton scattering of photons off of electrons to create extremely thin energy bandwidth gamma-rays. In this research a Monte Carlo code developed by Lawrence Livermore National Laboratory, known as COG, was used to investigate detector designs for use with mono-energetic gamma-ray sources to quantify plutonium in spent nuclear fuel assemblies. It is shown that the technique is viable for the quantification of plutonium in fresh and spent mixed oxide fuel. However, these calculations suggest that Nuclear Resonance Fluorescence is not sufficiently sensitive for low plutonium-239 concentrations, <1% atom percent, which is the concentration present in spent pressurized water reactor fuel. Investigation into the lack of sensitivity was inconclusive. A more in-depth analysis of COG’s capabilities in this area should be conducted.