Measurement technique of plutonium and minor actinides using nuclear resonance fluorescence with laser Compton scattering gamma-rays

摘要

We have proposed a new nondestructive assay method for ~(239)Pu in spent nuclear fuel includingmelted fuels of the Fukushima plants. In our proposed system ~(239)Pu is measured using nuclearresonance fluorescence (NRF) with a monochromatic gamma-ray beam. Such a gamma-raybeam is generated by Compton scattering of laser photons with high energy electrons. Thismethod has a crucial advantage that we can measure ~(239)Pu independent of the shape andchemical composition of a melted fuel sample. Two types of backgrounds may affect theprecision of the measured quantity of ~(239)Pu. We estimate the statistical error of expected NRFsignals and background originated from radioactivities in the spent fuel. We concluded that it ispossible to assay 1% ~(239)Pu content in a spent fuel with 1.6% statistical precision during the 4000second measurement time using our proposed system with incident gamma-rays around 5 MeV.