Nondestructive assay of plutonium and minor actinide in spent fuel using nuclear resonance fluorescence with laser Compton scattering γ-rays

We propose a new nondestructive assay method for 235U, 239Pu, and minor actinides in spent nuclear fuel assembly in a water pool. Nuclear fuel materials are detected using nuclear resonance fluorescence (NRF) with laser Compton scattering (LCS) γ-rays. The NRF assay can provide a finger print of each isotope since the NRF γ-ray energy is characteristic of a specific nuclide. We design a high-flux LCS γ-ray source, in which γ-rays are generated by collision of laser photons provided from Yb-doped fiber laser and electrons from energy recovery linac. This system has following advantages; this can detect isotopes of most elements behind heavy materials such as uranium of a thickness of several centimeters, and analyze the fuel assembly in a water pool. A simulation calculation shows that we can detect 1% fraction 239Pu in all the fuel rods with statistical error lower than 2% using the high flux LCS γ-ray source and the measurement time of 4000 s.