Analysis of Minor Actinides in Mixed Oxide Fuel Irradiated in Fast Reactor, (I)

Abstract

The MOX (mixed oxide) fuels, 29.97wt% (analytical value is 28.08 wt%) plutonium in 8.3 or 12.1 wt% enriched uranium were irradiated up to 120 GWd/t in the MARK-II core of JOYO. The irradiated MOX fuels were dissolved in 8 M nitric acid solution. Anion exchange chromatographic procedures were developed for the isolation of neptunium contained in these MOX solutions. Neptunium-237 was separated from the other actinides by using the developed chromatographic technique and the content of 237Np was determined by a spectrometry. It was found that the content of 237Np slightly increased with increasing burnup. The content did not exceed 0.08 wt% in the 30 wt% MOX fuels irradiated up to about 120 GWd/t. Model calculation by ORIGEN-2 reproduces well the observed content of 237Np.